diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 911bf5e661..8ee1d75eca 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -46,10 +46,23 @@ jobs:
         uses: actions/checkout@v3
 
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@v3
+        uses: simplex-chat/docker-setup-buildx-action@v3
+
+      - name: Install PostgreSQL 15 client tools
+        if: matrix.os == '22.04'
+        shell: bash
+        run: |
+          # Import the repository signing key
+          sudo install -d /usr/share/postgresql-common/pgdg
+          sudo curl -o /usr/share/postgresql-common/pgdg/apt.postgresql.org.asc --fail https://www.postgresql.org/media/keys/ACCC4CF8.asc
+          # Add the PostgreSQL APT repository
+          sudo sh -c 'echo "deb [signed-by=/usr/share/postgresql-common/pgdg/apt.postgresql.org.asc] https://apt.postgresql.org/pub/repos/apt $(lsb_release -cs)-pgdg main" > /etc/apt/sources.list.d/pgdg.list'
+          # Update repository and install postgresql tools
+          sudo apt update
+          sudo apt -y install postgresql-client-15
 
       - name: Build and cache Docker image
-        uses: docker/build-push-action@v6
+        uses: simplex-chat/docker-build-push-action@v6
         with:
           context: .
           load: true
@@ -82,7 +95,7 @@ jobs:
             build/${{ matrix.platform_name }}:latest
 
       - name: Build smp-server (postgresql) and tests
-        shell: docker exec -t builder sh {0}
+        shell: docker exec -t builder sh -eu {0}
         run: |
           cabal update
           cabal build --jobs=$(nproc) --enable-tests -fserver_postgres
@@ -106,7 +119,7 @@ jobs:
           docker cp builder:/out/smp-server ./smp-server-postgres-ubuntu-${{ matrix.platform_name }}
 
       - name: Build everything else (standard)
-        shell: docker exec -t builder sh {0}
+        shell: docker exec -t builder sh -eu {0}
         run: |
           cabal build --jobs=$(nproc)
           mkdir -p /out
@@ -127,7 +140,7 @@ jobs:
       - name: Build changelog
         if: startsWith(github.ref, 'refs/tags/v')
         id: build_changelog
-        uses: mikepenz/release-changelog-builder-action@v5
+        uses: simplex-chat/release-changelog-builder-action@v5
         with:
           configuration: .github/changelog_conf.json
           failOnError: true
@@ -138,7 +151,7 @@ jobs:
 
       - name: Create release
         if: startsWith(github.ref, 'refs/tags/v') && matrix.ghc != '8.10.7'
-        uses: softprops/action-gh-release@v2
+        uses: simplex-chat/action-gh-release@v2
         with:
           body: |
             See full changelog [here](https://github.com/simplex-chat/simplexmq/blob/master/CHANGELOG.md).
diff --git a/.github/workflows/docker-image.yml b/.github/workflows/docker-image.yml
index efd74552ff..6e3e25e82d 100644
--- a/.github/workflows/docker-image.yml
+++ b/.github/workflows/docker-image.yml
@@ -22,14 +22,14 @@ jobs:
         uses: actions/checkout@v4
 
       - name: Log in to Docker Hub
-        uses: docker/login-action@v3
+        uses: simplex-chat/docker-login-action@v3
         with:
           username: ${{ secrets.DOCKERHUB_USERNAME }}
           password: ${{ secrets.DOCKERHUB_PASSWORD }}
 
       - name: Extract metadata for Docker image
         id: meta
-        uses: docker/metadata-action@v5
+        uses: simplex-chat/docker-metadata-action@v5
         with:
           images: ${{ secrets.DOCKERHUB_USERNAME }}/${{ matrix.app }}
           flavor: |
@@ -40,7 +40,7 @@ jobs:
             type=semver,pattern=v{{major}}
 
       - name: Build and push Docker image
-        uses: docker/build-push-action@v6
+        uses: simplex-chat/docker-build-push-action@v6
         with:
           push: true
           build-args: |
diff --git a/apps/smp-server/static/.well-known/apple-app-site-association b/apps/smp-server/static/.well-known/apple-app-site-association
new file mode 100644
index 0000000000..3b513fe61e
--- /dev/null
+++ b/apps/smp-server/static/.well-known/apple-app-site-association
@@ -0,0 +1,49 @@
+{
+  "applinks": {
+    "details": [
+      {
+        "appIDs": [
+          "5NN7GUYB6T.chat.simplex.app"
+        ],
+        "components": [
+          {
+            "/": "/contact/*"
+          },
+          {
+            "/": "/contact"
+          },
+          {
+            "/": "/invitation/*"
+          },
+          {
+            "/": "/invitation"
+          },
+          {
+            "/": "/a/*"
+          },
+          {
+            "/": "/a"
+          },
+          {
+            "/": "/c/*"
+          },
+          {
+            "/": "/c"
+          },
+          {
+            "/": "/g/*"
+          },
+          {
+            "/": "/g"
+          },
+          {
+            "/": "/i/*"
+          },
+          {
+            "/": "/i"
+          }
+        ]
+      }
+    ]
+  }
+}
\ No newline at end of file
diff --git a/apps/smp-server/static/.well-known/assetlinks.json b/apps/smp-server/static/.well-known/assetlinks.json
new file mode 100644
index 0000000000..e19f8a4c1a
--- /dev/null
+++ b/apps/smp-server/static/.well-known/assetlinks.json
@@ -0,0 +1,16 @@
+[
+    {
+        "relation": [
+            "delegate_permission/common.handle_all_urls"
+        ],
+        "target": {
+            "namespace": "android_app",
+            "package_name": "chat.simplex.app",
+            "sha256_cert_fingerprints": [
+                "5E:3E:DC:C2:00:FB:A8:D5:F4:88:F3:CA:4C:32:5B:05:78:C5:6A:9C:03:A1:CC:B5:92:9C:D7:5C:7E:57:E2:4D",
+                "3C:52:C4:FD:3C:AD:1C:07:C9:B0:0A:70:80:E3:58:FA:B9:FE:FC:B8:AF:5A:EC:14:77:65:F1:6D:0F:21:AD:85",
+                "AE:C1:95:DC:FD:46:14:BD:3A:91:EC:26:D1:D5:14:C8:75:71:C5:CC:8D:CF:48:08:3F:92:83:14:3C:A2:B9:A6"
+            ]
+        }
+    }
+]
diff --git a/apps/smp-server/static/a/index.html b/apps/smp-server/static/a/index.html
new file mode 120000
index 0000000000..1140bcf31d
--- /dev/null
+++ b/apps/smp-server/static/a/index.html
@@ -0,0 +1 @@
+../link.html
\ No newline at end of file
diff --git a/apps/smp-server/static/c/index.html b/apps/smp-server/static/c/index.html
new file mode 120000
index 0000000000..1140bcf31d
--- /dev/null
+++ b/apps/smp-server/static/c/index.html
@@ -0,0 +1 @@
+../link.html
\ No newline at end of file
diff --git a/apps/smp-server/static/i/index.html b/apps/smp-server/static/i/index.html
new file mode 120000
index 0000000000..1140bcf31d
--- /dev/null
+++ b/apps/smp-server/static/i/index.html
@@ -0,0 +1 @@
+../link.html
\ No newline at end of file
diff --git a/apps/smp-server/static/link.html b/apps/smp-server/static/link.html
index cbab7324f7..b5be2d7abc 100644
--- a/apps/smp-server/static/link.html
+++ b/apps/smp-server/static/link.html
@@ -142,8 +142,7 @@
     class="hidden xl:block h-screen pt-[66px] bg-white dark:bg-gradient-radial-mobile dark:lg:bg-gradient-radial">
     <div class="container m-auto h-full flex items-center justify-between px-5">
       <div class="flex flex-col items-start justify-center w-full">
-        <h1 class="text-[38px] leading-[43px] font-bold max-w-[500px] mb-[30px] primary-header-contact">You received a
-          1-time link to connect on SimpleX Chat</h1>
+        <h1 class="text-[38px] leading-[43px] font-bold max-w-[500px] mb-[30px] primary-header-contact">This is a one-time link of the SimpleX&nbsp;network user</h1>
         <h2
           class="text-[20px] leading-[28px] text-[#606C71] dark:text-white font-bold max-w-[475px] mb-[80px] secondary-header-contact">
           Scan the QR code with the SimpleX Chat app on your phone or tablet.</h2>
@@ -184,10 +183,8 @@ <h1 class="text-[38px] leading-[43px] font-bold max-w-[500px] mb-[30px] primary-
     class="block xl:hidden pt-[106px] py-[90px] bg-white dark:bg-gradient-radial-mobile dark:lg:bg-gradient-radial">
     <div class="container m-auto px-5">
       <div class="flex flex-col items-center">
-        <h1 class="text-[28px] font-bold text-center max-w-[602px] mb-[40px] primary-header-contact">You received a
-          1-time link to connect on SimpleX Chat</h1>
-        <p class="text-[20px] leading-[28px] text-grey-black dark:text-white font-medium mb-[30px]">To make a
-          connection:</p>
+        <h1 class="text-[28px] font-bold text-center max-w-[602px] mb-[40px] primary-header-contact">This is a one-time link of the SimpleX&nbsp;network user</h1>
+        <p class="text-[20px] leading-[28px] text-grey-black dark:text-white font-medium mb-[30px]">To make a connection:</p>
         <div
           class="flex flex-col justify-center items-center p-4 w-full max-w-[468px] min-h-[131px] rounded-[30px] border-[1px] border-[#A8B0B4] dark:border-white border-opacity-60 mb-6 relative">
           <p class="text-xl font-medium text-grey-black dark:text-white mb-4">Install SimpleX app</p>
@@ -506,13 +503,15 @@ <h2 class="text-xl font-bold">If you already installed SimpleX Chat for the term
     const url = window.location.href
     const messageElements = document.getElementsByClassName('primary-header-contact')
 
-    if (url.includes('/invitation')) {
-      for (let element of messageElements) {
-        element.textContent = 'You received a 1-time link to connect on SimpleX Chat'
-      }
-    } else {
-      for (let element of messageElements) {
-        element.textContent = 'You received an address to connect on SimpleX Chat'
+    for (let element of messageElements) {
+      if (url.includes('/g') || url.includes('&data=%7B%22groupLinkId%22%3A')) {
+        element.innerHTML = 'This is a public group address on SimpleX&nbsp;network'
+      } else if (url.includes('/a') || url.includes('/contact')) {
+        element.innerHTML = 'This is a public address of the SimpleX&nbsp;network user'
+      } else if (url.includes('/i') || url.includes('/invitation')) {
+        element.innerHTML = 'This is a one-time link of the SimpleX&nbsp;network user'
+      } else if (url.includes('/c')) {
+        element.innerHTML = 'This is a public channel address on SimpleX&nbsp;network'
       }
     }
   </script>
diff --git a/apps/smp-server/static/media/contact.js b/apps/smp-server/static/media/contact.js
index b1a99b74f9..6df303f6c4 100644
--- a/apps/smp-server/static/media/contact.js
+++ b/apps/smp-server/static/media/contact.js
@@ -20,7 +20,18 @@
     parsedURI.pathname = "/" + action
     connURI = parsedURI.toString()
     console.log("connection URI: ", connURI)
-    mobileConnURIanchor.href = "simplex:" + parsedURI.pathname + parsedURI.hash
+    const hash = parsedURI.hash
+    const hostname = parsedURI.hostname
+    let appURI = "simplex:" + parsedURI.pathname
+    appURI += action.length > 1 // not short link
+              ? hash
+              : !hash.includes("?") // otherwise add server hostname
+              ? hash + "?h=" + hostname // no parameters
+              : !hash.includes("?h=") && !hash.includes("&h=")
+              ? hash + "&h=" + hostname // no "h" parameter
+              : hash.replace(/([?&])h=([^&]+)/, `$1h=${hostname},$2`) // add as the first hostname to "h" parameter
+    mobileConnURIanchor.href = appURI
+    console.log("app URI: ", appURI)
     connURIel.innerText = "/c " + connURI
     for (const connQRCode of connQRCodes) {
       try {
diff --git a/apps/smp-server/web/Static.hs b/apps/smp-server/web/Static.hs
index c4a3e84f7f..50e4415eb8 100644
--- a/apps/smp-server/web/Static.hs
+++ b/apps/smp-server/web/Static.hs
@@ -14,7 +14,8 @@ import Data.Maybe (fromMaybe)
 import Data.String (fromString)
 import Data.Text.Encoding (encodeUtf8)
 import Network.Socket (getPeerName)
-import Network.Wai (Application)
+import Network.Wai (Application, Request (..))
+import Network.Wai.Application.Static (StaticSettings (..))
 import qualified Network.Wai.Application.Static as S
 import qualified Network.Wai.Handler.Warp as W
 import qualified Network.Wai.Handler.Warp.Internal as WI
@@ -31,12 +32,13 @@ import System.Directory (createDirectoryIfMissing)
 import System.FilePath
 import UnliftIO.Concurrent (forkFinally)
 import UnliftIO.Exception (bracket, finally)
+import qualified WaiAppStatic.Types as WAT
 
 serveStaticFiles :: EmbeddedWebParams -> IO ()
 serveStaticFiles EmbeddedWebParams {webStaticPath, webHttpPort, webHttpsParams} = do
   forM_ webHttpPort $ \port -> flip forkFinally (\e -> logError $ "HTTP server crashed: " <> tshow e) $ do
     logInfo $ "Serving static site on port " <> tshow port
-    W.runSettings (mkSettings port) (S.staticApp $ S.defaultFileServerSettings webStaticPath)
+    W.runSettings (mkSettings port) app
   forM_ webHttpsParams $ \WebHttpsParams {port, cert, key} -> flip forkFinally (\e -> logError $ "HTTPS server crashed: " <> tshow e) $ do
     logInfo $ "Serving static site on port " <> tshow port <> " (TLS)"
     WT.runTLS (WT.tlsSettings cert key) (mkSettings port) app
@@ -72,23 +74,44 @@ warpSettings :: W.Settings
 warpSettings = W.setGracefulShutdownTimeout (Just 1) W.defaultSettings
 
 staticFiles :: FilePath -> Application
-staticFiles root = S.staticApp settings
+staticFiles root = S.staticApp settings . changeWellKnownPath
   where
-    settings = (S.defaultFileServerSettings root)
-      { S.ssListing = Nothing
-      }
+    settings = defSettings {ssListing = Nothing, ssGetMimeType = getMimeType}
+    defSettings = S.defaultFileServerSettings root
+    getMimeType f
+      | WAT.fromPiece (WAT.fileName f) == "apple-app-site-association" = pure "application/json"
+      | otherwise = (ssGetMimeType defSettings) f
+    changeWellKnownPath req = case pathInfo req of
+      ".well-known" : rest ->
+        req
+          { pathInfo = "well-known" : rest,
+            rawPathInfo = "/well-known/" <> B.drop pfxLen (rawPathInfo req)
+          }
+      _ -> req
+    pfxLen = B.length "/.well-known/"
 
 generateSite :: ServerInformation -> Maybe TransportHost -> FilePath -> IO ()
 generateSite si onionHost sitePath = do
   createDirectoryIfMissing True sitePath
   B.writeFile (sitePath </> "index.html") $ serverInformation si onionHost
-  createDirectoryIfMissing True $ sitePath </> "media"
-  forM_ E.mediaContent $ \(path, bs) -> B.writeFile (sitePath </> "media" </> path) bs
-  createDirectoryIfMissing True $ sitePath </> "contact"
-  B.writeFile (sitePath </> "contact" </> "index.html") E.linkHtml
-  createDirectoryIfMissing True $ sitePath </> "invitation"
-  B.writeFile (sitePath </> "invitation" </> "index.html") E.linkHtml
+  copyDir "media" E.mediaContent
+  -- `.well-known` path is re-written in changeWellKnownPath,
+  -- staticApp does not allow hidden folders.
+  copyDir "well-known" E.wellKnown
+  createLinkPage "contact"
+  createLinkPage "invitation"
+  createLinkPage "a"
+  createLinkPage "c"
+  createLinkPage "g"
+  createLinkPage "i"
   logInfo $ "Generated static site contents at " <> tshow sitePath
+  where
+    copyDir dir content = do
+      createDirectoryIfMissing True $ sitePath </> dir
+      forM_ content $ \(path, s) -> B.writeFile (sitePath </> dir </> path) s
+    createLinkPage path = do
+      createDirectoryIfMissing True $ sitePath </> path
+      B.writeFile (sitePath </> path </> "index.html") E.linkHtml
 
 serverInformation :: ServerInformation -> Maybe TransportHost -> ByteString
 serverInformation ServerInformation {config, information} onionHost = render E.indexHtml substs
diff --git a/apps/smp-server/web/Static/Embedded.hs b/apps/smp-server/web/Static/Embedded.hs
index 23698dd6f9..c1c4fde2f7 100644
--- a/apps/smp-server/web/Static/Embedded.hs
+++ b/apps/smp-server/web/Static/Embedded.hs
@@ -13,3 +13,6 @@ linkHtml = $(embedFile "apps/smp-server/static/link.html")
 
 mediaContent :: [(FilePath, ByteString)]
 mediaContent = $(embedDir "apps/smp-server/static/media/")
+
+wellKnown :: [(FilePath, ByteString)]
+wellKnown = $(embedDir "apps/smp-server/static/.well-known/")
diff --git a/rfcs/2025-03-16-smp-queues.md b/rfcs/2025-03-16-smp-queues.md
index a0f845a43a..5b46b383b5 100644
--- a/rfcs/2025-03-16-smp-queues.md
+++ b/rfcs/2025-03-16-smp-queues.md
@@ -65,36 +65,32 @@ Proposed NEW command replaces SenderCanSecure with QueueMode, adds link data, an
 ```haskell
 NEW :: NewQueueRequest -> Command Recipient
 
-data NewQueueRequest = NewQueueRequest
+data NewQueueReq = NewQueueReq
   { rcvAuthKey :: RcvPublicAuthKey,
     rcvDhKey :: RcvPublicDhKey,
-    basicAuth :: Maybe BasicAuth,
+    auth_ :: Maybe BasicAuth,
     subMode :: SubscriptionMode,
-    ntfRequest :: Maybe NtfRequest,
-    queueLink :: Maybe QueueLink -- it is Maybe to allow testing and staged roll-out
+    queueData :: Maybe QueueReqData,
+    ntfCreds :: Maybe NewNtfCreds
   }
 
--- To allow updating the existing contact addresses without changing them.
--- This command would fail on queues that support sndSecure and also on new queues created with QLMessaging.
--- RecipientId is entity ID.
--- The response to this command is `OK`.
-LNEW :: LinkId -> QueueLinkData -> Command Recipient
-
 -- Replaces NKEY command
 -- This avoids additional command required from the client to enable notifications.
 -- Further changes would move NotifierId generation to the client, and including a signed and encrypted command to be forwarded by SMP server to notification server.
 data NtfRequest = NtfRequest NtfPublicAuthKey RcvNtfPublicDhKey
 
--- QLMessaging implies that sender can secure the queue.
--- LinkId is not used with QLMessaging, to prevent the possibility of checking when connection is established by re-using the same link ID when creating another queue – the creating would have to fail if it is used.
--- LinkId is required with QLContact, to have shorter link - it will be derived from the link_uri. And in this case we do not need to prevent checks that this queue exists.
-data QueueLink = QLMessaging QueueLinkData | QLContact LinkId QueueLinkData
+-- QRMessaging implies that sender can secure the queue.
+-- LinkId is not used with QRMessaging, to prevent the possibility of checking when connection is established by re-using the same link ID when creating another queue – the creating would have to fail if it is used.
+-- LinkId is required with QRContact, to have shorter link - it will be derived from the link_uri. And in this case we do not need to prevent checks that this queue exists.
+data QueueReqData = QRMessaging (Maybe QueueLinkData) | QRContact (Maybe (LinkId, QueueLinkData))
 
-data QueueLinkData = QueueLinkData EncImmutableDataBytes EncUserDataBytes
+-- SenderId should be computed client-side as the first 24 bytes of sha3-384(correlation_id),
+-- The server must verify it and reject if it is not.
+type QueueLinkData = (SenderId, EncImmutableDataBytes, EncUserDataBytes)
 
-newtype EncImmutableDataBytes = EncImmutableDataBytes ByteString
+type EncImmutableDataBytes = ByteString
 
-newtype EncUserDataBytes = EncUserDataBytes ByteString
+type EncUserDataBytes = ByteString
 
 -- We need to use binary encoding for AConnectionRequestUri to reduce its size
 -- connReq including the full link allows connection redundancy.
@@ -128,27 +124,45 @@ data ServerNtfCreds = ServerNtfCreds NotifierId RcvNtfPublicDhKey -- NotifierId
 In addition to that we add the command allowing to update and also to retrieve and, optionally, secure the queue and get link data in one request, to have only one request:
 
 ```haskell
--- With RecipientId as entity ID, the command to update mutable part of link data
--- The response is OK here.
-LSET :: EncUserDataBytes -> Command Recipient
+-- This command allows to set all data or to update mutlable part of contact address queue.
+-- This command should fail on queues that support sndSecure and also on new queues created with QRMessaging.
+-- This should fail if LinkId or immutable part of data is changed with the update, but will succeed if only mutable part is updated, so it can be retried.
+-- Entity ID is RecipientId.
+-- The response to this command is `OK`.
+LSET :: LinkId -> QueueLinkData -> Command Recipient
+
+-- Delete should link and associated data
+-- Entity ID is RecipientId
+LDEL :: Command Recipient
 
 -- To be used with 1-time links.
 -- Sender's key provided on the first request prevents observers from undetectably accessing 1-time link data.
--- If queue mode is QLContact (and queue does NOT allow sndSecure) the command will fail, same as SKEY.
+-- If queue mode is QRContact (and queue does NOT allow sndSecure) the command will fail, same as SKEY.
 -- Once queue is secured, the key must be the same in subsequent requests - to allow retries in case of network failures, and to prevent passive attacks.
 -- The difference with securing queues is that queues allow sending unsecured messages to queues that allow sndSecure (for backwards compatibility), and 1-time links will NOT allow retrieving link data without securing the queue at the same time, preventing undetected access by observers.
--- Entity ID is LinkId here
+-- Entity ID is LinkId
 LKEY :: SndPublicAuthKey -> Command Sender
 
--- If queue mode is QLMessaging the command will fail.
--- Entity ID is LinkId here
+-- If queue mode is QRMessaging the command will fail.
+-- Entity ID is LinkId
 LGET :: Command Sender
 
--- Response to LKEY and LGET
--- Entity ID is LinkId here
-LINK :: SenderId -> QueueLinkData -> BrokerMsg
+-- Response to LGET, LSKEY and LSGET
+-- Entity ID is the same as in the command
+LNK :: SenderId -> QueueLinkData -> BrokerMsg
 ```
 
+To both include sender_id into the full link before the server response, and to prevent "oracle attack" when a failure to create the queue with the supplied `sender_id` can be used as a proof of queue existense, it is proposed that `sender_id` is computed client-side as the first 24 bytes of 48 in `sha3-384(correlation_id)` and validated server-side, where `corelation_id` is the transmission correlation ID.
+
+To allow retries and to avoid regenerating all queue data, NEW command must be idempotent, and `correlation_id` must be preserved in command for queue creation, so that the same `correlation_id` and all other data is used in retries. `correlation_id` should be removed after queue creation success.
+
+To allow retries, every time the command is sent a new random `correlation_id` and new `sender_id` / `link_id` should be used on each attempt, because other IDs would be generated randomly on the server, and in case the previous command succeeded on the server but failed to be communicated to the client, the retry will fail if the same ID is used.
+
+Alternative solutions considered and rejected:
+- additional request to save queue data, after `sender_id` is returned by the server. The scenarios that require short links are interactive - creating user addresses and 1-time invitations - so making two requests instead of one would make the UX worse.
+- include empty sender_id in the immutable data and have it replaced by the accepting party with `sender_id` received in `LINK` response - both a weird design, and might create possibility for some attacks via server, especially for contact addresses.
+- making NEW commands idempotent. Doing it would require generating all IDs client-side, not only `sender_id`. It increases complexity, and it is not really necessary as the only scenarios when retries are needed are async NEW commands, that do not require short links. For future short links of chat relays the retries are much less likely, as chat relays will have good network connections.
+
 ## Algorithm to prepare and to interpret queue link data.
 
 For contact addresses this approach follows the design proposed in [Short links](./2024-06-21-short-links.md) RFC - when link id is derived from the same random binary as key. For 1-time invitations link ID is independent and server-generated, to prevent existense checks.
@@ -166,6 +180,42 @@ For contact addresses this approach follows the design proposed in [Short links]
 - for one time links the sender must authorize the request to retrieve the data, the key is provided with the first request, preventing undetected access by link observers.
 - having received the link data, the client can now decrypt it using secret_box.
 
+## Improved algorithm to prepare and to interpret queue link data.
+
+This scheme reduces the size of the binary in the link from 48 bytes (72 in case of 1-time links) to 32 bytes (56 bytes for 1-time links).
+
+For immutable data.
+
+1. `link_key = SHA3-256(immutable_data)` - used as part of link, and to encrypt content.
+2. HKDF:
+  1) contact address: `(link_id, key) = HKDF(link_key, 56 bytes)`.
+  2) 1-time invitation: `key = HKDF(link_key, 32 bytes)`, `link-id` - server-generated. 
+3. 
+3. Random `nonce1` (for immutable data), to be stored with the link data.
+4. Encrypt: `(ct1, tag1) = secret_box(immutable_data, key, nonce1)`.
+5. Store: `(nonce1, ct1, tag1)` stored as immutable link data.
+
+For mutable user data:
+
+1. Random `nonce2` and the same key are used.
+2. Sign `user_data` with key included in `immutable_data`.
+3. Encrypt: `(ct2, tag2) = secret_box(signed_used_data, key, nonce2)`.
+4. Store: `(nonce2, ct2, tag2)`
+
+Link recipient:
+
+1. Receives `link_key` in the link, for 1-time invitations also `link_id`.
+2. HKDF:
+  1) contact address: `(link_id, key) = HKDF(link_key, 56 bytes)`.
+  2) 1-time invitation: `key = HKDF(link_key, 32 bytes)`.
+3. Retrieves via `link_id`: `(nonce1, ct1, tag1)` and `(nonce2, ct2, tag2)`.
+4. Decrypt: `immutable_data = decrypt (nonce1, ct1, tag1)`.
+5. Verify: `SHA3-256(immutable_data) == link_key`, abort if not.
+6. Decrypt: `signed_used_data = decrypt(nonce2, ct2, tag2)`
+7. Verify signature with key in immutable data.
+
+While using content hash as encryption key is unconventional, it is not completely unheard of - e.g., it is used in convergent encryption (although in our case using random nonce makes it not convergent, but other use cases suggest that this approach preserves encryption security). It is particularly acceptable for our use case, as `immutable_data` contains mostly random keys.
+
 ## Threat model
 
 **Compromised SMP server**
@@ -214,11 +264,10 @@ The proposed syntax:
 shortConnectionLink = %s"https://" smpServerHost "/" linkUri [ "?" param *( "&" param ) ]
 smpServerHost = <hostname> ; RFC1123, RFC5891
 linkUri = %s"i#" serverInfo oneTimeLinkBytes / %s"c#" serverInfo contactLinkBytes
-oneTimeLinkBytes = <base64url(linkId | linkKey | linkAuthTag)> ; 60 bytes / 80 base64 encoded characters
-contactLinkBytes = <base64url(linkKey | linkAuthTag)> ; 48 bytes / 64 base64 encoded characters
+oneTimeLinkBytes = <base64url(linkId | linkKey)> ; 56 bytes / 75 base64 encoded characters
+contactLinkBytes = <base64url(linkKey)> ; 32 bytes / 43 base64 encoded characters
 ; linkId - 96 bits/24 bytes
 ; linkKey - 256 bits/32 bytes
-; linkAuthTag - 128 bits/16 bytes auth tag from encryption of immutable link data>
 
 serverInfo = [fingerprint "@" [hostnames "/"]] ; not needed for preset servers, required otherwise - the clients must refuse to connect if they don't have fingerprint in the code.
 
@@ -228,28 +277,28 @@ hostnames = "h=" <hostname> *( "," <hostname> ) ; additional hostnames, e.g. oni
 
 To have shorter links fingerpring and additional server hostnames do not need to be specified for preconfigured servers, even if they are disabled - they can be used from the client code. Any user defined servers will require including additional hosts and server fingerprint.
 
-Example one-time link for preset server (108 characters):
+Example one-time link for preset server (103 characters):
 
 ```
-https://smp12.simplex.im/i#abcdefghij0123456789abcdefghij0123456789abcdefghij0123456789abcdefghij0123456789
+https://smp12.simplex.im/i#abcdefghij0123456789abcdefghij0123456789abcdefghij0123456789abcdefghij01234
 ```
 
-Example contact link for preset server (92 characters):
+Example contact link for preset server (71 characters):
 
 ```
-https://smp12.simplex.im/c#abcdefghij0123456789abcdefghij0123456789abcdefghij0123456789abcd
+https://smp12.simplex.im/c#abcdefghij0123456789abcdefghij0123456789abc
 ```
 
-Example contact link for user-defined server (with fingerprint, but without onion hostname - 136 characters):
+Example contact link for user-defined server (with fingerprint, but without onion hostname - 115 characters):
 
 ```
-https://smp1.example.com/c#0YuTwO05YJWS8rkjn9eLJDjQhFKvIYd8d4xG8X1blIU@abcdefghij0123456789abcdefghij0123456789abcdefghij0123456789abcd
+https://smp1.example.com/c#0YuTwO05YJWS8rkjn9eLJDjQhFKvIYd8d4xG8X1blIU@abcdefghij0123456789abcdefghij0123456789abc
 ```
 
-Example contact link for user-defined server (with fingerprint ant onion hostname - 199 characters):
+Example contact link for user-defined server (with fingerprint ant onion hostname - 178 characters):
 
 ```
-https://smp1.example.com/c#0YuTwO05YJWS8rkjn9eLJDjQhFKvIYd8d4xG8X1blIU@beccx4yfxxbvyhqypaavemqurytl6hozr47wfc7uuecacjqdvwpw2xid.onion/abcdefghij0123456789abcdefghij0123456789abcdefghij0123456789abcd
+https://smp1.example.com/c#0YuTwO05YJWS8rkjn9eLJDjQhFKvIYd8d4xG8X1blIU@beccx4yfxxbvyhqypaavemqurytl6hozr47wfc7uuecacjqdvwpw2xid.onion/abcdefghij0123456789abcdefghij0123456789abc
 ```
 
 For the links to work in the browser the servers must provide server pages.
diff --git a/rfcs/2025-03-30-ios-notifications-3.md b/rfcs/2025-03-30-ios-notifications-3.md
new file mode 100644
index 0000000000..4415257671
--- /dev/null
+++ b/rfcs/2025-03-30-ios-notifications-3.md
@@ -0,0 +1,93 @@
+# New notifications protocol
+
+## Problem
+
+iOS notifications have these problems:
+- iOS notification service crashes exceeding memory limit. This is being addressed by changes in GHC RTS.
+- there is a large number of connections, because each member in a group requires individual connection. This will improve with chat relays when each group would require 2-3 connections.
+- some notification may be not shown if notification with reply/mention is skipped, and instead some other message is delivered, which may be muted. This would not improve without some changes, as notifications may be skipped anyway.
+- client devices delay communication with ntf server because it is done in background, and by that time the app may be suspended.
+- notification server represents a bottleneck, as it has to be owned by the app vendor, and the current design when ntf server subscribes to notifications scales very badly.
+
+This RFC is based on the previous [RFC related to notifications](./2024-09-25-ios-notifications-2.md).
+
+## Solution
+
+As notification server has to know client token and currently it associates subscriptions with this token anyway, we are not gaining any privacy and security by using per-subscription keys - both authorization and encryption keys of notification subscription can be dropped.
+
+We still need to store the list of queue IDs associated with the token on the notification server, but we do not need any per-queue keys on the notification server, and we don't need subscriptions - it's effectively a simple set of IDs, with no other information.
+
+In this case, when queue is created the client would supply notifier ID - it has to be derived from correlation ID, to prevent existense check (see previous RFC). As we also supply sender ID, instead of deriving it as sha3-192 of correlation ID, they both can be derived as sha3-384 and split to two IDs - 24 bytes each.
+
+The notification server will maintain a rotating list of server keys with the latest key communicated to the client every time the token is registered and checked. The keys would expire after, say, 1 week or 1 month, and removed from notification server on expiration.
+
+The packet containing association between notifier queue ID and token will be crypto_box encrypted using key agreement between identified notification server master key and an ephemeral per packet (effectively, per-queue) client-key.
+
+Deleting the queue may also include encrypted packet that would verify that the client deleted the queue.
+
+Instead of notification server subscribing to the notifications creating a lot of traffic for the queues without messages, the SMP server would push notifications via NTF server connection (whether via NTF or via SMP protocol). This could be used as a mechanism to migrate existing queues when with the next subscription the notification server would communicate it's address to SMP server and this association would be stored together with the queue.
+
+## Protocol design
+
+Additional/changed SMP commands:
+
+```haskell
+-- register notification server
+-- should be signed with server key
+NSRV :: NtfServerCreds -> Command NtfServer
+
+-- response
+NSID :: NtfServerId -> BrokerMsg
+
+-- to communicate which server is responsible for the queue
+-- should be signed with queue key
+NSUB :: Maybe NtfServerId -> Command Notifier
+
+-- subscribe to notificaions from all queues associated with the server
+-- should be signed with server key
+-- entity ID - NtfServerId
+NSSUB :: Command NtfServer
+
+data NtfServerCreds = NtfServerCreds
+  { server :: NtfServer,
+    -- NTF server certificate chain that should match fingerpring in address
+    cert :: X.CertificateChain,
+    -- server autorizatio key to sign server subscription requests
+    authKey :: X.SignedExact X.PubKey
+  }
+
+-- entity ID is recipient ID
+NSKEY :: NtfSubscription -> Command Recipient 
+
+data NtfSubscription = NtfSubscription
+  -- key to encrypt notifications e2e with the client
+  { ntfPubDbKey :: RcvNtfPublicDhKey,
+    ntfServer :: NtfServer,
+    -- should be linked to correlation ID to prevent existense check
+    -- the ID sent to notification server could be its hash?
+    ntfId :: NotifierId,
+    encNtfTokenAssoc :: EncDataBytes
+  }
+
+-- before the encryption - equivalent to NSUB command, but without key to authorize requests to specific queue
+data NtfTokenAssoc = NtfTokenAssoc
+  { signature :: SignatureEd25519,
+    tknId :: NtfTokenId,
+    ntfQueue :: SMPQueueNtf
+  }
+```
+
+SMP server will need to maintain the list of Ntf servers and their credentials, and when NSSUB arrives to make only one subscription. When message arrives it would deliver notification to the correct connection via queue / ntf server association.
+
+Ntf server needs to maintain three indices to the same data:
+- `(smpServer, queueId) -> tokenId` - to deliver notification to the correct token
+- `tokenId -> [smpServer -> [queueId]]` - to remove all queues when token is removed, and to store/update these associations effficiently - store log may have one compact line per token (after compacting), or per token/server combination.
+- `[smpServer]` - array of SMP servers to subscribe to.
+
+## Mention notifications
+
+Currently we are marking messages with T (true) for messages that require notifications and F (false) for messages that don't require. Sender does not know whether the recipient has notifications disabled, enabled or in mentions-only mode.
+
+The proposal is to:
+- add additional values to this metadata, e.g. 2 (priority) and 3 (high priority) (and T/F could be sent as 0/1 respectively) - that is, to deliver notifications even if notifications are generally disabled (they can still be further filtered by the client).
+- instead of deleting notification credentials when notifications are disabled - which is costly - communicate to SMP server the change of notificaion priority level, e.g. the client could set minimal notification priority to deliver notifications, where 0 would mean disabling it completely, 1 enable for all, 2 for priority 2+, 3 for priority 3. The downside here is that it could be used for timing correlation of queues in the group, but it already can be used on bulk deletions of ntf credentials for these queues and when sending messages.
diff --git a/rfcs/2025-04-04-short-links-for-groups.md b/rfcs/2025-04-04-short-links-for-groups.md
new file mode 100644
index 0000000000..90938acec0
--- /dev/null
+++ b/rfcs/2025-04-04-short-links-for-groups.md
@@ -0,0 +1,159 @@
+# Using short links as group links
+
+## Problem
+
+To use the short links for groups these problems has to be / can be solved:
+1. recognizing link as a group link.
+2. permanent link with the ability to change chat relays.
+3. binding owners signatures to the link.
+4. allowing to add/remove owners, both to share ownership and for reliability in case of one owner losing keys/access.
+
+While current short links solve problems 1-3 (via contact type, and via extension of user data in the link), the problem 4 is solved only partially.
+
+We could include the current list of root owners in the user data, and we could send any history of ownership changes from this baseline as a short blockchain on joining the group, we still requrie one master owner to retain access to the queue associated with the group.
+
+## Possible solution approaches
+
+1. "Kick this can down the road" - ignore this problem until there is a namespace, and a group name can be associated with multiple queues.
+
+Pros: simple and reasonable, and it suggests postponing multisig for owners too. The users can still see the list of owners and their keys in user data of the link, and receive admin roster signed by owners on joining.
+
+Cons: if this "master owner" loses the access to the device, no further changes to group profile will be possible.
+
+2. The queue access can be shared by sharing the key and recipient IDs with all owners.
+
+The problems:
+- preventing MITM attack between owners (this protect exists for other solutions too).
+- protecting these credentials from chat relays. So somehow there should be direct key agreement between members allowing to send e2e encrypted message inaccessible to chat relays.
+
+Pros: simpler than alternatives, and still provides protection against losing the key.
+Cons:
+- quite clunky, and requires the new primitive anyway (e2e encryption).
+- no multisig
+
+This could possibly be evolved into the requirement to have a direct connection with other owners, and verifying the security code before they have access to group.
+
+3. Allow "joint management" of SMP queues.
+
+SMP servers can support multiple recipients for contact queues:\
+- subscription would be possible to the "subscriber recipient".
+- all other changes (update data, change subscriber recipient, add or remove recipients) would require multiple recipient signatures on SMP command in line with n-of-m multisig rules, that the command sender would have to collect out-of-band (from SMP protocol point of view).
+
+Pros: allows joint ownership, and protects from losing access to master owner device.
+Cons:
+- complicates queue abstraction with approach that is not needed for most queues.
+- still retains the server as a single point of failure.
+
+4. Introduce "group" as a new type of entity managed by SMP servers.
+
+SMP servers would provide a separate set of commands for managing group records that would include in an encrypted container:
+- the group profile
+- the list of chat relay links
+- the list of owner member IDs with their public keys
+- multisig rules
+- alternative group entity locations
+- possibly, a globally unique group identity (as the hash of the initial/seed group data).
+
+While the server domain would be used as the hostname in group link, it may contain alternative hosts (not just hostnames of the same server), both in the link and in the group record data.
+
+Pros: separates additional complexity to where it is needed, allowing reliability and redundancy for group ownership.
+Cons: complexity, coupling between SMP and chat protocol.
+
+## Design for channel/group as a separate queue mode
+
+Option 1.
+
+A queue mode "channel" when owners are represented by their individual queues (either a separate mode, or a submode of "channel", or just normal contact address queues). In this case sending message to channel queue would broadcast message to queue owners, without exposing even the number of owners.
+
+Pros:
+- allows chat relays to send messages to all owners (e.g., channel can be secured with the list of snd keys, one per relay).
+- quite easy to evolve from the current design.
+- extensible.
+Cons:
+- close to "solution in search of a problem".
+- does not require data model changes - channel queue would simply have a list of owner "recipient IDs", and each owner queue would also point to channel.
+
+Option 2.
+
+Also a separate queue mode "channel", but instead of having a linked owner queues, it would simply maintain a list of owner keys to maintain the data. In this case, messages cannot be sent to this "queue" at all.
+
+Pros:
+- simpler design.
+- we could allow sending messages to it too, with the "main" owner receiving them. This could be negotiated in the protocol.
+- it may be easier to migrate the current groups, as the admin link would be this queue (although for public groups in directory it would have to be recreated anyway).
+- Possibly, when queue is created there should be a flag whether it should accept unsigned messages - then contact addresses would be created with unsigned messages ON, messages queues, once SKEY is universally supported, with unsigned messages OFF, and channel queues with unsigned messages OFF too for new public queues.
+Cons:
+- if no messages are accepted, this is not even a queue.
+- no way to directly contact owners (maybe it is not a downside, as for relays there would be a communication channel anyway as part of the group).
+
+Option 2 looks more simple and attractive, implementing server broadcast for SMP seems unnecessary, as while it could have been used for simple groups, it does not solve such problems as spam and pre-moderation anyway - it requires a higher level protocol.
+
+The command to update owner keys would be `RKEY` with the list of keys, and we can make `NEW` accept multiple keys too, although the use case here is less clear.
+
+## Multiple owners managing queue data.
+
+Option 1: Use the same keys in SMP as when signing queue data.
+
+Option 2: Use different keys.
+
+The value here could be that the server could validate these signatures too, and also maintain the chain of key changes. While tempting, it is probably unnecessary, and this chain of ownership is better to be maintained on chat relay level, as there are no size constraints on the size of this chain. Also, it is better for metadata privacy to not couple transport and chat protocol keys.
+
+We still need to bind the mutable data updates to the "genesis" signature key (the one included in the immutable data).
+
+The proposed design:
+
+- when mutable data is signed by genesis key, then it is bound, and no changes is needed.
+- mutable data may be signed by the key of the new owner, in which case mutable part itself must contain the binding. We could also use ring signature to sign the mutable data, concealing which owner signed the data - that would increase the signature size from 64 bytes to `32 * (n + 1)` bytes.
+
+Current mutable data:
+
+```haskell
+data UserLinkData = UserLinkData
+  { agentVRange :: VersionRangeSMPA,
+    userData :: ConnInfo
+  }
+```
+
+Proposed mutable data:
+
+```haskell
+data UserLinkData = UserLinkData
+  { agentVRange :: VersionRangeSMPA,
+    owners :: [OwnerInfo]
+    userData :: ConnInfo
+  }
+
+type OwnerId = ByteString
+
+data OwnerInfo = OwnerInfo
+  { ownerId :: OwnerId, -- unique in the list, application specific - e.g., MemberId
+    ownerKey :: PublicKeyEd25519,
+    -- owner signature of sender ID,
+    -- confirms that the owner agreed with being the owner,
+    -- prevents a member being added as an owner without consent.
+    ownerSig :: SignatureEd25519,
+    -- owner authorization, sig(ownerId || ownerKey, prevKey), where prevKey is either a "genesis key" or some other key previously signed by the genesis key.
+    authOwnerId :: OwnerId, -- null for "genesis"
+    authOwnerSig :: SignatureEd25519
+  }
+```
+
+The size of the OwnerInfo record encoding is:
+- ownerId: 1 + 12
+- ownerKey: 1 + 32
+- ownerSig: 1 + 64
+- ownerAuthId: 1 + 12
+- ownerAuthSig: 1 + 64
+
+~189 bytes, so we should practically limit the number of owners to say 8 - 1 original + 7 addiitonal. Original creator could use a different key as a "genesis" key, to conceal creator identity from other members, and it needs to include the record with memberId anyway.
+
+The structure is simplified, and it does not allow arbitrary ownership changes. Its purpose is not to comprehensively manage ownership changes - while it is possible with a generic blockchain, it seems not appropriate at this stage, - but rather to ensure access continuity and that the server cannot modify the data (although nothing prevents the server from removing the data completely or from serving the previous version of the data).
+
+For example it would only allow any given owner to remove subsequenty added owners, preserving the group link and identity, but it won't allow removing owners that signed this owner authorization. So owners are not equal, with the creator having the highest rank and being able to remove all additional owners, and owners authorise by creator can remove all other owners but themselves and creator, and so on - they have to maintain the chain that authorized themselves, at least. We could explicitely include owner rank into OwnerInfo, or we could require that they are sorted by rank, or the rank can be simply derived from signatures.
+
+When additional owners want to be added to the group, they would have to provide any of the current owners:
+- the key for SMP commands authorization - this will be passed to SMP server together with other keys. There could be either RKEY to pass all keys (some risk to miss some, or of race conditions), or RADD/RGET/RDEL to add and remove recipient keys, which has no risk of race conditions.
+- the signature of the immutable data by their member key included in their profile.
+- the current owner would then include their member key into the queue data, and update it with LSET command. In any case there should be some simple consensus protocol between owners for owner changes, and it has to be maintained as a blockchain by owners and by chat relays, as otherwise it may lead to race conditions with LSET command.
+
+Potentially, there could be one command to update keys and link data, so that they are consistent.
diff --git a/simplexmq.cabal b/simplexmq.cabal
index e262e0e81f..67b323c099 100644
--- a/simplexmq.cabal
+++ b/simplexmq.cabal
@@ -121,6 +121,7 @@ library
       Simplex.Messaging.Crypto.SNTRUP761.Bindings.Defines
       Simplex.Messaging.Crypto.SNTRUP761.Bindings.FFI
       Simplex.Messaging.Crypto.SNTRUP761.Bindings.RNG
+      Simplex.Messaging.Crypto.ShortLink
       Simplex.Messaging.Encoding
       Simplex.Messaging.Encoding.String
       Simplex.Messaging.Notifications.Client
@@ -158,6 +159,7 @@ library
           Simplex.Messaging.Agent.Store.Postgres.Migrations.App
           Simplex.Messaging.Agent.Store.Postgres.Migrations.M20241210_initial
           Simplex.Messaging.Agent.Store.Postgres.Migrations.M20250203_msg_bodies
+          Simplex.Messaging.Agent.Store.Postgres.Migrations.M20250322_short_links
   else
       exposed-modules:
           Simplex.Messaging.Agent.Store.SQLite
@@ -203,6 +205,7 @@ library
           Simplex.Messaging.Agent.Store.SQLite.Migrations.M20241007_rcv_queues_last_broker_ts
           Simplex.Messaging.Agent.Store.SQLite.Migrations.M20241224_ratchet_e2e_snd_params
           Simplex.Messaging.Agent.Store.SQLite.Migrations.M20250203_msg_bodies
+          Simplex.Messaging.Agent.Store.SQLite.Migrations.M20250322_short_links
   if !flag(client_library)
       exposed-modules:
           Simplex.FileTransfer.Client.Main
@@ -366,6 +369,8 @@ executable ntf-server
 executable smp-server
   if flag(client_library)
       buildable: False
+  if flag(server_postgres)
+    cpp-options: -DdbServerPostgres
   main-is: Main.hs
   other-modules:
       Static
@@ -441,6 +446,7 @@ test-suite simplexmq-test
       AgentTests.MigrationTests
       AgentTests.NotificationTests
       AgentTests.ServerChoice
+      AgentTests.ShortLinkTests
       CLITests
       CoreTests.BatchingTests
       CoreTests.CryptoFileTests
@@ -476,6 +482,9 @@ test-suite simplexmq-test
       other-modules:
           AgentTests.SchemaDump
           AgentTests.SQLiteTests
+  if flag(server_postgres)
+      other-modules:
+          ServerTests.SchemaDump  
   hs-source-dirs:
       tests
       apps/smp-server/web
@@ -531,11 +540,13 @@ test-suite simplexmq-test
   if flag(client_postgres)
     cpp-options: -DdbPostgres
   else
+    build-depends:
+        memory
+      , sqlcipher-simple
+  if !flag(client_postgres) || flag(server_postgres)
     build-depends:
         deepseq ==1.4.*
-      , memory
       , process
-      , sqlcipher-simple
   if flag(client_postgres) || flag(server_postgres)
     build-depends:
         postgresql-simple ==0.7.*
diff --git a/src/Simplex/Messaging/Agent.hs b/src/Simplex/Messaging/Agent.hs
index 15a2744faa..34d6bbc970 100644
--- a/src/Simplex/Messaging/Agent.hs
+++ b/src/Simplex/Messaging/Agent.hs
@@ -56,6 +56,10 @@ module Simplex.Messaging.Agent
     deleteConnectionAsync,
     deleteConnectionsAsync,
     createConnection,
+    setContactShortLink,
+    deleteContactShortLink,
+    getConnShortLink,
+    deleteLocalInvShortLink,
     changeConnectionUser,
     prepareConnectionToJoin,
     prepareConnectionToAccept,
@@ -177,17 +181,39 @@ import Simplex.Messaging.Agent.Store.Common (DBStore)
 import qualified Simplex.Messaging.Agent.Store.DB as DB
 import Simplex.Messaging.Agent.Store.Interface (closeDBStore, execSQL, getCurrentMigrations)
 import Simplex.Messaging.Agent.Store.Shared (UpMigration (..), upMigration)
-import Simplex.Messaging.Client (SMPClientError, ServerTransmission (..), ServerTransmissionBatch, temporaryClientError, unexpectedResponse)
+import Simplex.Messaging.Client (SMPClientError, ServerTransmission (..), ServerTransmissionBatch, nonBlockingWriteTBQueue, temporaryClientError, unexpectedResponse)
 import qualified Simplex.Messaging.Crypto as C
 import Simplex.Messaging.Crypto.File (CryptoFile, CryptoFileArgs)
 import Simplex.Messaging.Crypto.Ratchet (PQEncryption, PQSupport (..), pattern PQEncOff, pattern PQEncOn, pattern PQSupportOff, pattern PQSupportOn)
+import qualified Simplex.Messaging.Crypto.ShortLink as SL
 import qualified Simplex.Messaging.Crypto.Ratchet as CR
 import Simplex.Messaging.Encoding
 import Simplex.Messaging.Encoding.String
 import Simplex.Messaging.Notifications.Protocol (DeviceToken, NtfRegCode (NtfRegCode), NtfTknStatus (..), NtfTokenId, PNMessageData (..), pnMessagesP)
 import Simplex.Messaging.Notifications.Types
 import Simplex.Messaging.Parsers (parse)
-import Simplex.Messaging.Protocol (BrokerMsg, Cmd (..), ErrorType (AUTH), MsgBody, MsgFlags (..), NtfServer, ProtoServerWithAuth, ProtocolType (..), ProtocolTypeI (..), SMPMsgMeta, SParty (..), SProtocolType (..), SndPublicAuthKey, SubscriptionMode (..), UserProtocol, VersionSMPC, sndAuthKeySMPClientVersion)
+import Simplex.Messaging.Protocol
+  ( BrokerMsg,
+    Cmd (..),
+    ErrorType (AUTH),
+    MsgBody,
+    MsgFlags (..),
+    NtfServer,
+    ProtoServerWithAuth (..),
+    ProtocolServer (..),
+    ProtocolType (..),
+    ProtocolTypeI (..),
+    QueueLinkData,
+    QueueMode (..),
+    SMPMsgMeta,
+    SParty (..),
+    SProtocolType (..),
+    SndPublicAuthKey,
+    SubscriptionMode (..),
+    UserProtocol,
+    VersionSMPC,
+    senderCanSecure,
+  )
 import qualified Simplex.Messaging.Protocol as SMP
 import Simplex.Messaging.ServiceScheme (ServiceScheme (..))
 import qualified Simplex.Messaging.TMap as TM
@@ -340,10 +366,29 @@ deleteConnectionsAsync c waitDelivery = withAgentEnv c . deleteConnectionsAsync'
 {-# INLINE deleteConnectionsAsync #-}
 
 -- | Create SMP agent connection (NEW command)
-createConnection :: AgentClient -> UserId -> Bool -> SConnectionMode c -> Maybe CRClientData -> CR.InitialKeys -> SubscriptionMode -> AE (ConnId, ConnectionRequestUri c)
-createConnection c userId enableNtfs = withAgentEnv c .:: newConn c userId enableNtfs
+createConnection :: ConnectionModeI c => AgentClient -> UserId -> Bool -> SConnectionMode c -> Maybe ConnInfo -> Maybe CRClientData -> CR.InitialKeys -> SubscriptionMode -> AE (ConnId, CreatedConnLink c)
+createConnection c userId enableNtfs = withAgentEnv c .::. newConn c userId enableNtfs
 {-# INLINE createConnection #-}
 
+-- | Create or update user's contact connection short link
+setContactShortLink :: AgentClient -> ConnId -> ConnInfo -> AE (ConnShortLink 'CMContact)
+setContactShortLink c = withAgentEnv c .: setContactShortLink' c
+{-# INLINE setContactShortLink #-}
+
+deleteContactShortLink :: AgentClient -> ConnId -> AE ()
+deleteContactShortLink c = withAgentEnv c . deleteContactShortLink' c
+{-# INLINE deleteContactShortLink #-}
+
+-- | Get and verify data from short link. For 1-time invitations it preserves the key to allow retries
+getConnShortLink :: AgentClient -> UserId -> ConnShortLink c -> AE (ConnectionRequestUri c, ConnLinkData c)
+getConnShortLink c = withAgentEnv c .: getConnShortLink' c
+{-# INLINE getConnShortLink #-}
+
+-- | This irreversibly deletes short link data, and it won't be retrievable again
+deleteLocalInvShortLink :: AgentClient -> ConnShortLink 'CMInvitation -> AE ()
+deleteLocalInvShortLink c = withAgentEnv c . deleteLocalInvShortLink' c
+{-# INLINE deleteLocalInvShortLink #-}
+
 -- | Changes the user id associated with a connection
 changeConnectionUser :: AgentClient -> UserId -> ConnId -> UserId -> AE ()
 changeConnectionUser c oldUserId connId newUserId = withAgentEnv c $ changeConnectionUser' c oldUserId connId newUserId
@@ -356,10 +401,12 @@ changeConnectionUser c oldUserId connId newUserId = withAgentEnv c $ changeConne
 -- "link deleted" (SMP AUTH) interactively, so this approach is simpler overall.
 prepareConnectionToJoin :: AgentClient -> UserId -> Bool -> ConnectionRequestUri c -> PQSupport -> AE ConnId
 prepareConnectionToJoin c userId enableNtfs = withAgentEnv c .: newConnToJoin c userId "" enableNtfs
+{-# INLINE prepareConnectionToJoin #-}
 
 -- | Create SMP agent connection without queue (to be joined with acceptContact passing invitation ID).
 prepareConnectionToAccept :: AgentClient -> Bool -> ConfirmationId -> PQSupport -> AE ConnId
 prepareConnectionToAccept c enableNtfs = withAgentEnv c .: newConnToAccept c "" enableNtfs
+{-# INLINE prepareConnectionToAccept #-}
 
 -- | Join SMP agent connection (JOIN command).
 joinConnection :: AgentClient -> UserId -> ConnId -> Bool -> ConnectionRequestUri c -> ConnInfo -> PQSupport -> SubscriptionMode -> AE SndQueueSecured
@@ -686,6 +733,8 @@ newConnNoQueues c userId enableNtfs cMode pqSupport = do
   let cData = ConnData {userId, connId = "", connAgentVersion, enableNtfs, lastExternalSndId = 0, deleted = False, ratchetSyncState = RSOk, pqSupport}
   withStore c $ \db -> createNewConn db g cData cMode
 
+-- TODO [short links] TBC, but probably we will need async join for contact addresses as the contact will be created after user confirming the connection,
+-- and join should retry, the same as 1-time invitation joins.
 joinConnAsync :: AgentClient -> UserId -> ACorrId -> Bool -> ConnectionRequestUri c -> ConnInfo -> PQSupport -> SubscriptionMode -> AM ConnId
 joinConnAsync c userId corrId enableNtfs cReqUri@CRInvitationUri {} cInfo pqSup subMode = do
   withInvLock c (strEncode cReqUri) "joinConnAsync" $ do
@@ -776,12 +825,84 @@ switchConnectionAsync' c corrId connId =
             pure . connectionStats $ DuplexConnection cData rqs' sqs
       _ -> throwE $ CMD PROHIBITED "switchConnectionAsync: not duplex"
 
-newConn :: AgentClient -> UserId -> Bool -> SConnectionMode c -> Maybe CRClientData -> CR.InitialKeys -> SubscriptionMode -> AM (ConnId, ConnectionRequestUri c)
-newConn c userId enableNtfs cMode clientData pqInitKeys subMode = do
+newConn :: ConnectionModeI c => AgentClient -> UserId -> Bool -> SConnectionMode c -> Maybe ConnInfo -> Maybe CRClientData -> CR.InitialKeys -> SubscriptionMode -> AM (ConnId, CreatedConnLink c)
+newConn c userId enableNtfs cMode userData_ clientData pqInitKeys subMode = do
   srv <- getSMPServer c userId
   connId <- newConnNoQueues c userId enableNtfs cMode (CR.connPQEncryption pqInitKeys)
-  cReq <- newRcvConnSrv c userId connId enableNtfs cMode clientData pqInitKeys subMode srv
-  pure (connId, cReq)
+  (connId,) <$> newRcvConnSrv c userId connId enableNtfs cMode userData_ clientData pqInitKeys subMode srv
+    `catchE` \e -> withStore' c (`deleteConnRecord` connId) >> throwE e
+
+setContactShortLink' :: AgentClient -> ConnId -> ConnInfo -> AM (ConnShortLink 'CMContact)
+setContactShortLink' c connId userData = 
+  withConnLock c connId "setContactShortLink" $
+    withStore c (`getConn` connId) >>= \case
+      SomeConn _ (ContactConnection _ rq) -> do
+        (lnkId, linkKey, d) <- prepareLinkData rq
+        addQueueLink c rq lnkId d
+        pure $ CSLContact SLSServer CCTContact (qServer rq) linkKey
+      _ -> throwE $ CMD PROHIBITED "setContactShortLink: not contact address"
+  where
+    prepareLinkData :: RcvQueue -> AM (SMP.LinkId, LinkKey, QueueLinkData)
+    prepareLinkData rq@RcvQueue {server, sndId, e2ePrivKey, shortLink} = do
+      g <- asks random
+      AgentConfig {smpClientVRange = vr, smpAgentVRange} <- asks config
+      case shortLink of
+        Just ShortLinkCreds {shortLinkId, shortLinkKey, linkPrivSigKey, linkEncFixedData} -> do
+          let (linkId, k) = SL.contactShortLinkKdf shortLinkKey
+          unless (shortLinkId == linkId) $ throwE $ INTERNAL "setContactShortLink: link ID is not derived from link"
+          d <- liftError id $ SL.encryptUserData g k $ SL.encodeSignUserData linkPrivSigKey smpAgentVRange userData
+          pure (linkId, shortLinkKey, (linkEncFixedData, d))
+        Nothing -> do
+          sigKeys@(_, privSigKey) <- atomically $ C.generateKeyPair @'C.Ed25519 g
+          let qUri = SMPQueueUri vr $ SMPQueueAddress server sndId (C.publicKey e2ePrivKey) (Just QMContact)
+              connReq = CRContactUri $ ConnReqUriData SSSimplex smpAgentVRange [qUri] Nothing
+              (linkKey, linkData) = SL.encodeSignLinkData sigKeys smpAgentVRange connReq userData
+              (linkId, k) = SL.contactShortLinkKdf linkKey
+          srvData <- liftError id $ SL.encryptLinkData g k linkData
+          let slCreds = ShortLinkCreds linkId linkKey privSigKey (fst srvData)
+          withStore' c $ \db -> updateShortLinkCreds db rq slCreds
+          pure (linkId, linkKey, srvData)
+
+deleteContactShortLink' :: AgentClient -> ConnId -> AM ()
+deleteContactShortLink' c connId =
+  withConnLock c connId "deleteContactShortLink" $
+    withStore c (`getConn` connId) >>= \case
+      SomeConn _ (ContactConnection _ rq) -> deleteQueueLink c rq
+      _ -> throwE $ CMD PROHIBITED "deleteContactShortLink: not contact address"
+
+-- TODO [short links] remove 1-time invitation data and link ID from the server after the message is sent.
+getConnShortLink' :: forall c. AgentClient -> UserId -> ConnShortLink c -> AM (ConnectionRequestUri c, ConnLinkData c)
+getConnShortLink' c userId = \case
+  CSLInvitation _ srv linkId linkKey -> do
+    g <- asks random
+    invLink <- withStore' c $ \db -> do
+      getInvShortLink db srv linkId >>= \case
+        Just sl@InvShortLink {linkKey = lk} | linkKey == lk -> pure sl
+        _ -> do
+          (sndPublicKey, sndPrivateKey) <- atomically $ C.generateAuthKeyPair C.SEd25519 g
+          let sl = InvShortLink {server = srv, linkId, linkKey, sndPrivateKey, sndPublicKey, sndId = Nothing}
+          createInvShortLink db sl
+          pure sl
+    let k = SL.invShortLinkKdf linkKey
+    ld@(sndId, _) <- secureGetQueueLink c userId invLink
+    withStore' c $ \db -> setInvShortLinkSndId db invLink sndId
+    decryptData srv linkKey k ld
+  CSLContact _ _ srv linkKey -> do
+    let (linkId, k) = SL.contactShortLinkKdf linkKey
+    ld <- getQueueLink c userId srv linkId
+    decryptData srv linkKey k ld
+  where
+    decryptData :: ConnectionModeI c => SMPServer -> LinkKey -> C.SbKey -> (SMP.SenderId, QueueLinkData) -> AM (ConnectionRequestUri c, ConnLinkData c)
+    decryptData srv linkKey k (sndId, d) = do
+      r@(cReq, _) <- liftEither $ SL.decryptLinkData @c linkKey k d
+      let (srv', sndId') = qAddress (connReqQueue cReq)
+      unless (srv `sameSrvHost` srv' && sndId == sndId') $
+        throwE $ AGENT $ A_LINK "different address"
+      pure r
+    sameSrvHost ProtocolServer {host = h :| _} ProtocolServer {host = hs} = h `elem` hs
+
+deleteLocalInvShortLink' :: AgentClient -> ConnShortLink 'CMInvitation -> AM ()
+deleteLocalInvShortLink' c (CSLInvitation _ srv linkId _) = withStore' c $ \db -> deleteInvShortLink db srv linkId
 
 changeConnectionUser' :: AgentClient -> UserId -> ConnId -> UserId -> AM ()
 changeConnectionUser' c oldUserId connId newUserId = do
@@ -793,28 +914,83 @@ changeConnectionUser' c oldUserId connId newUserId = do
   where
     updateConn = withStore' c $ \db -> setConnUserId db oldUserId connId newUserId
 
-newRcvConnSrv :: AgentClient -> UserId -> ConnId -> Bool -> SConnectionMode c -> Maybe CRClientData -> CR.InitialKeys -> SubscriptionMode -> SMPServerWithAuth -> AM (ConnectionRequestUri c)
-newRcvConnSrv c userId connId enableNtfs cMode clientData pqInitKeys subMode srvWithAuth@(ProtoServerWithAuth srv _) = do
+newRcvConnSrv :: forall c. ConnectionModeI c => AgentClient -> UserId -> ConnId -> Bool -> SConnectionMode c -> Maybe ConnInfo -> Maybe CRClientData -> CR.InitialKeys -> SubscriptionMode -> SMPServerWithAuth -> AM (CreatedConnLink c)
+newRcvConnSrv c userId connId enableNtfs cMode userData_ clientData pqInitKeys subMode srvWithAuth@(ProtoServerWithAuth srv _) = do
   case (cMode, pqInitKeys) of
     (SCMContact, CR.IKUsePQ) -> throwE $ CMD PROHIBITED "newRcvConnSrv"
     _ -> pure ()
-  AgentConfig {smpClientVRange, smpAgentVRange, e2eEncryptVRange} <- asks config
-  let sndSecure = case cMode of SCMInvitation -> True; SCMContact -> False
-  (rq, qUri, tSess, sessId) <- newRcvQueue c userId connId srvWithAuth smpClientVRange subMode sndSecure `catchAgentError` \e -> liftIO (print e) >> throwE e
-  atomically $ incSMPServerStat c userId srv connCreated
-  rq' <- withStore c $ \db -> updateNewConnRcv db connId rq
-  lift . when (subMode == SMSubscribe) $ addNewQueueSubscription c rq' tSess sessId
-  when enableNtfs $ do
-    ns <- asks ntfSupervisor
-    atomically $ sendNtfSubCommand ns (NSCCreate, [connId])
-  let crData = ConnReqUriData SSSimplex smpAgentVRange [qUri] clientData
-  case cMode of
-    SCMContact -> pure $ CRContactUri crData
-    SCMInvitation -> do
+  e2eKeys <- atomically . C.generateKeyPair =<< asks random
+  case userData_ of
+    Just d -> do
+      (nonce, qUri, cReq, qd) <- prepareLinkData d $ fst e2eKeys
+      (rq, qUri') <- createRcvQueue (Just nonce) qd e2eKeys
+      connReqWithShortLink qUri cReq qUri' (shortLink rq)
+    Nothing -> do
+      let qd = case cMode of SCMContact -> CQRContact Nothing; SCMInvitation -> CQRMessaging Nothing
+      (_, qUri) <- createRcvQueue Nothing qd e2eKeys
+      (`CCLink` Nothing) <$> createConnReq qUri
+  where
+    createRcvQueue :: Maybe C.CbNonce -> ClntQueueReqData -> C.KeyPairX25519 -> AM (RcvQueue, SMPQueueUri)
+    createRcvQueue nonce_ qd e2eKeys = do
+      AgentConfig {smpClientVRange = vr} <- asks config
+      -- TODO [notifications] send correct NTF credentials here
+      -- let ntfCreds_ = Nothing 
+      (rq, qUri, tSess, sessId) <- newRcvQueue_ c userId connId srvWithAuth vr qd subMode nonce_ e2eKeys `catchAgentError` \e -> liftIO (print e) >> throwE e
+      atomically $ incSMPServerStat c userId srv connCreated
+      rq' <- withStore c $ \db -> updateNewConnRcv db connId rq
+      lift . when (subMode == SMSubscribe) $ addNewQueueSubscription c rq' tSess sessId
+      when enableNtfs $ do
+        ns <- asks ntfSupervisor
+        atomically $ sendNtfSubCommand ns (NSCCreate, [connId])
+      pure (rq', qUri)
+    createConnReq :: SMPQueueUri -> AM (ConnectionRequestUri c)
+    createConnReq qUri = do
+      AgentConfig {smpAgentVRange, e2eEncryptVRange} <- asks config
+      let crData = ConnReqUriData SSSimplex smpAgentVRange [qUri] clientData
+      case cMode of
+        SCMContact -> pure $ CRContactUri crData
+        SCMInvitation -> do
+          g <- asks random
+          (pk1, pk2, pKem, e2eRcvParams) <- liftIO $ CR.generateRcvE2EParams g (maxVersion e2eEncryptVRange) (CR.initialPQEncryption pqInitKeys)
+          withStore' c $ \db -> createRatchetX3dhKeys db connId pk1 pk2 pKem
+          pure $ CRInvitationUri crData $ toVersionRangeT e2eRcvParams e2eEncryptVRange
+    prepareLinkData :: ConnInfo -> C.PublicKeyX25519 -> AM (C.CbNonce, SMPQueueUri, ConnectionRequestUri c, ClntQueueReqData)
+    prepareLinkData userData e2eDhKey = do
       g <- asks random
-      (pk1, pk2, pKem, e2eRcvParams) <- liftIO $ CR.generateRcvE2EParams g (maxVersion e2eEncryptVRange) (CR.initialPQEncryption pqInitKeys)
-      withStore' c $ \db -> createRatchetX3dhKeys db connId pk1 pk2 pKem
-      pure $ CRInvitationUri crData $ toVersionRangeT e2eRcvParams e2eEncryptVRange
+      nonce@(C.CbNonce corrId) <- atomically $ C.randomCbNonce g
+      sigKeys@(_, privSigKey) <- atomically $ C.generateKeyPair @'C.Ed25519 g
+      AgentConfig {smpClientVRange = vr, smpAgentVRange} <- asks config
+      -- TODO [notifications] the remaining 24 bytes are reserved for notifier ID
+      let sndId = SMP.EntityId $ B.take 24 $ C.sha3_384 corrId
+          qm = case cMode of SCMContact -> QMContact; SCMInvitation -> QMMessaging
+          qUri = SMPQueueUri vr $ SMPQueueAddress srv sndId e2eDhKey (Just qm)
+      connReq <- createConnReq qUri
+      let (linkKey, linkData) = SL.encodeSignLinkData sigKeys smpAgentVRange connReq userData
+      qd <- case cMode of
+        SCMContact -> do
+          let (linkId, k) = SL.contactShortLinkKdf linkKey
+          srvData <- liftError id $ SL.encryptLinkData g k linkData
+          pure $ CQRContact $ Just CQRData {linkKey, privSigKey, srvReq = (linkId, (sndId, srvData))}
+        SCMInvitation -> do
+          let k = SL.invShortLinkKdf linkKey
+          srvData <- liftError id $ SL.encryptLinkData g k linkData
+          pure $ CQRMessaging $ Just CQRData {linkKey, privSigKey, srvReq = (sndId, srvData)}
+      pure (nonce, qUri, connReq, qd)
+    connReqWithShortLink :: SMPQueueUri -> ConnectionRequestUri c -> SMPQueueUri -> Maybe ShortLinkCreds -> AM (CreatedConnLink c)
+    connReqWithShortLink qUri cReq qUri' shortLink = case shortLink of
+      Just ShortLinkCreds {shortLinkId, shortLinkKey}
+        | qUri == qUri'  ->
+            let link = case cReq of
+                  CRContactUri _ -> CSLContact SLSServer CCTContact srv shortLinkKey
+                  CRInvitationUri {} -> CSLInvitation SLSServer srv shortLinkId shortLinkKey
+             in pure $ CCLink cReq (Just link)
+        | otherwise -> throwE $ INTERNAL "different rcv queue address"
+      Nothing ->
+        let updated (ConnReqUriData _ vr _ _) = (ConnReqUriData SSSimplex vr [qUri'] clientData)
+            cReq' = case cReq of
+              CRContactUri crData -> CRContactUri (updated crData)
+              CRInvitationUri crData e2eParams -> CRInvitationUri (updated crData) e2eParams
+         in pure $ CCLink cReq' Nothing
 
 newConnToJoin :: forall c. AgentClient -> UserId -> ConnId -> Bool -> ConnectionRequestUri c -> PQSupport -> AM ConnId
 newConnToJoin c userId connId enableNtfs cReq pqSup = case cReq of
@@ -844,49 +1020,52 @@ newConnToAccept c connId enableNtfs invId pqSup = do
 
 joinConn :: AgentClient -> UserId -> ConnId -> Bool -> ConnectionRequestUri c -> ConnInfo -> PQSupport -> SubscriptionMode -> AM SndQueueSecured
 joinConn c userId connId enableNtfs cReq cInfo pqSupport subMode = do
-  srv <- getNextSMPServer c userId [qServer cReqQueue]
+  srv <- getNextSMPServer c userId [qServer $ connReqQueue cReq]
   joinConnSrv c userId connId enableNtfs cReq cInfo pqSupport subMode srv
-  where
-    cReqQueue :: SMPQueueUri
-    cReqQueue = case cReq of
-      CRInvitationUri ConnReqUriData {crSmpQueues = q :| _} _ -> q
-      CRContactUri ConnReqUriData {crSmpQueues = q :| _} -> q
 
-startJoinInvitation :: AgentClient -> UserId -> ConnId -> Maybe SndQueue -> Bool -> ConnectionRequestUri 'CMInvitation -> PQSupport -> AM (ConnData, SndQueue, CR.SndE2ERatchetParams 'C.X448)
+connReqQueue :: ConnectionRequestUri c -> SMPQueueUri
+connReqQueue = \case
+  CRInvitationUri ConnReqUriData {crSmpQueues = q :| _} _ -> q
+  CRContactUri ConnReqUriData {crSmpQueues = q :| _} -> q
+
+startJoinInvitation :: AgentClient -> UserId -> ConnId -> Maybe SndQueue -> Bool -> ConnectionRequestUri 'CMInvitation -> PQSupport -> AM (ConnData, SndQueue, CR.SndE2ERatchetParams 'C.X448, Maybe SMP.LinkId)
 startJoinInvitation c userId connId sq_ enableNtfs cReqUri pqSup =
   lift (compatibleInvitationUri cReqUri) >>= \case
     Just (qInfo, Compatible e2eRcvParams@(CR.E2ERatchetParams v _ _ _), Compatible connAgentVersion) -> do
       -- this case avoids re-generating queue keys and subsequent failure of SKEY that timed out
       -- e2ePubKey is always present, it's Maybe historically
       let pqSupport = pqSup `CR.pqSupportAnd` versionPQSupport_ connAgentVersion (Just v)
-      (sq', e2eSndParams) <- case sq_ of
+      g <- asks random
+      maxSupported <- asks $ maxVersion . e2eEncryptVRange . config
+      let cData = ConnData {userId, connId, connAgentVersion, enableNtfs, lastExternalSndId = 0, deleted = False, ratchetSyncState = RSOk, pqSupport}
+      case sq_ of
         Just sq@SndQueue {e2ePubKey = Just _k} -> do
-          e2eSndParams <-
-            withStore' c (\db -> getSndRatchet db connId v) >>= \case
-              Right r -> pure $ snd r
+          e2eSndParams <- withStore c $ \db ->
+            getSndRatchet db connId v >>= \case
+              Right r -> pure $ Right $ snd r
               Left e -> do
-                atomically $ writeTBQueue (subQ c) ("", connId, AEvt SAEConn (ERR $ INTERNAL $ "no snd ratchet " <> show e))
-                createRatchet_ pqSupport e2eRcvParams
-          pure (sq, e2eSndParams)
+                nonBlockingWriteTBQueue (subQ c) ("", connId, AEvt SAEConn (ERR $ INTERNAL $ "no snd ratchet " <> show e))
+                runExceptT $ createRatchet_ db g maxSupported pqSupport e2eRcvParams
+          pure (cData, sq, e2eSndParams, Nothing)
         _ -> do
-          q <- lift $ fst <$> newSndQueue userId "" qInfo
-          e2eSndParams <- createRatchet_ pqSupport e2eRcvParams
+          let Compatible SMPQueueInfo {queueAddress = SMPQueueAddress {smpServer, senderId}} = qInfo
+          invLink_ <- withStore' c $ \db -> getInvShortLinkKeys db smpServer senderId
+          let lnkId_ = fst <$> invLink_
+              sndKeys_ = snd <$> invLink_
+          (q, _) <- lift $ newSndQueue userId "" qInfo sndKeys_
           withStore c $ \db -> runExceptT $ do
+            e2eSndParams <- createRatchet_ db g maxSupported pqSupport e2eRcvParams
             sq' <- maybe (ExceptT $ updateNewConnSnd db connId q) pure sq_
-            pure (sq', e2eSndParams)
-      let cData = ConnData {userId, connId, connAgentVersion, enableNtfs, lastExternalSndId = 0, deleted = False, ratchetSyncState = RSOk, pqSupport}
-      pure (cData, sq', e2eSndParams)
+            pure (cData, sq', e2eSndParams, lnkId_)
     Nothing -> throwE $ AGENT A_VERSION
   where
-    createRatchet_ pqSupport e2eRcvParams@(CR.E2ERatchetParams v _ rcDHRr kem_) = do
-      g <- asks random
+    createRatchet_ db g maxSupported pqSupport e2eRcvParams@(CR.E2ERatchetParams v _ rcDHRr kem_) = do
       (pk1, pk2, pKem, e2eSndParams) <- liftIO $ CR.generateSndE2EParams g v (CR.replyKEM_ v kem_ pqSupport)
       (_, rcDHRs) <- atomically $ C.generateKeyPair g
-      rcParams <- liftEitherWith cryptoError $ CR.pqX3dhSnd pk1 pk2 pKem e2eRcvParams
-      maxSupported <- asks $ maxVersion . e2eEncryptVRange . config
+      rcParams <- liftEitherWith (SEAgentError . cryptoError) $ CR.pqX3dhSnd pk1 pk2 pKem e2eRcvParams
       let rcVs = CR.RatchetVersions {current = v, maxSupported}
           rc = CR.initSndRatchet rcVs rcDHRr rcDHRs rcParams
-      withStore' c $ \db -> createSndRatchet db connId rc e2eSndParams
+      liftIO $ createSndRatchet db connId rc e2eSndParams
       pure e2eSndParams
 
 connRequestPQSupport :: AgentClient -> PQSupport -> ConnectionRequestUri c -> IO (Maybe (VersionSMPA, PQSupport))
@@ -931,16 +1110,22 @@ joinConnSrv c userId connId enableNtfs inv@CRInvitationUri {} cInfo pqSup subMod
   where
     doJoin :: Maybe SndQueue -> AM SndQueueSecured
     doJoin sq_ = do
-      (cData, sq, e2eSndParams) <- startJoinInvitation c userId connId sq_ enableNtfs inv pqSup
+      (cData, sq, e2eSndParams, lnkId_) <- startJoinInvitation c userId connId sq_ enableNtfs inv pqSup
       secureConfirmQueue c cData sq srv cInfo (Just e2eSndParams) subMode
+        >>= (mapM_ (delInvSL c connId srv) lnkId_ $>)
 joinConnSrv c userId connId enableNtfs cReqUri@CRContactUri {} cInfo pqSup subMode srv =
   lift (compatibleContactUri cReqUri) >>= \case
     Just (qInfo, vrsn) -> do
-      cReq <- newRcvConnSrv c userId connId enableNtfs SCMInvitation Nothing (CR.IKNoPQ pqSup) subMode srv
+      CCLink cReq _ <- newRcvConnSrv c userId connId enableNtfs SCMInvitation Nothing Nothing (CR.IKNoPQ pqSup) subMode srv
       void $ sendInvitation c userId connId qInfo vrsn cReq cInfo
       pure False
     Nothing -> throwE $ AGENT A_VERSION
 
+delInvSL :: AgentClient -> ConnId -> SMPServerWithAuth -> SMP.LinkId -> AM ()
+delInvSL c connId srv lnkId = 
+  withStore' c (\db -> deleteInvShortLink db (protoServer srv) lnkId) `catchE` \e ->
+    liftIO $ nonBlockingWriteTBQueue (subQ c) ("", connId, AEvt SAEConn (ERR $ INTERNAL $ "error deleting short link " <> show e))
+
 joinConnSrvAsync :: AgentClient -> UserId -> ConnId -> Bool -> ConnectionRequestUri c -> ConnInfo -> PQSupport -> SubscriptionMode -> SMPServerWithAuth -> AM SndQueueSecured
 joinConnSrvAsync c userId connId enableNtfs inv@CRInvitationUri {} cInfo pqSupport subMode srv = do
   SomeConn cType conn <- withStore c (`getConn` connId)
@@ -951,15 +1136,16 @@ joinConnSrvAsync c userId connId enableNtfs inv@CRInvitationUri {} cInfo pqSuppo
   where
     doJoin :: Maybe SndQueue -> AM SndQueueSecured
     doJoin sq_ = do
-      (cData, sq, e2eSndParams) <- startJoinInvitation c userId connId sq_ enableNtfs inv pqSupport
+      (cData, sq, e2eSndParams, lnkId_) <- startJoinInvitation c userId connId sq_ enableNtfs inv pqSupport
       secureConfirmQueueAsync c cData sq srv cInfo (Just e2eSndParams) subMode
+        >>= (mapM_ (delInvSL c connId srv) lnkId_ $>)
 joinConnSrvAsync _c _userId _connId _enableNtfs (CRContactUri _) _cInfo _subMode _pqSupport _srv = do
   throwE $ CMD PROHIBITED "joinConnSrvAsync"
 
 createReplyQueue :: AgentClient -> ConnData -> SndQueue -> SubscriptionMode -> SMPServerWithAuth -> AM SMPQueueInfo
 createReplyQueue c ConnData {userId, connId, enableNtfs} SndQueue {smpClientVersion} subMode srv = do
-  let sndSecure = smpClientVersion >= sndAuthKeySMPClientVersion
-  (rq, qUri, tSess, sessId) <- newRcvQueue c userId connId srv (versionToRange smpClientVersion) subMode sndSecure
+  -- TODO [notifications] send correct NTF credentials here
+  (rq, qUri, tSess, sessId) <- newRcvQueue c userId connId srv (versionToRange smpClientVersion) SCMInvitation subMode -- Nothing
   atomically $ incSMPServerStat c userId (qServer rq) connCreated
   let qInfo = toVersionT qUri smpClientVersion
   rq' <- withStore c $ \db -> upgradeSndConnToDuplex db connId rq
@@ -1240,7 +1426,7 @@ runCommandProcessing c@AgentClient {subQ} connId server_ Worker {doWork} = do
         NEW enableNtfs (ACM cMode) pqEnc subMode -> noServer $ do
           triedHosts <- newTVarIO S.empty
           tryCommand . withNextSrv c userId storageSrvs triedHosts [] $ \srv -> do
-            cReq <- newRcvConnSrv c userId connId enableNtfs cMode Nothing pqEnc subMode srv
+            CCLink cReq _ <- newRcvConnSrv c userId connId enableNtfs cMode Nothing Nothing pqEnc subMode srv
             notify $ INV (ACR cMode cReq)
         JOIN enableNtfs (ACR _ cReq@(CRInvitationUri ConnReqUriData {crSmpQueues = q :| _} _)) pqEnc subMode connInfo -> noServer $ do
           triedHosts <- newTVarIO S.empty
@@ -1486,7 +1672,7 @@ submitPendingMsg c cData sq = do
   void $ getDeliveryWorker True c cData sq
 
 runSmpQueueMsgDelivery :: AgentClient -> ConnData -> SndQueue -> (Worker, TMVar ()) -> AM ()
-runSmpQueueMsgDelivery c@AgentClient {subQ} ConnData {connId} sq@SndQueue {userId, server, sndSecure} (Worker {doWork}, qLock) = do
+runSmpQueueMsgDelivery c@AgentClient {subQ} ConnData {connId} sq@SndQueue {userId, server, queueMode} (Worker {doWork}, qLock) = do
   AgentConfig {messageRetryInterval = ri, messageTimeout, helloTimeout, quotaExceededTimeout} <- asks config
   forever $ do
     atomically $ endAgentOperation c AOSndNetwork
@@ -1572,7 +1758,7 @@ runSmpQueueMsgDelivery c@AgentClient {subQ} ConnData {connId} sq@SndQueue {userI
             Right proxySrv_ -> do
               case msgType of
                 AM_CONN_INFO
-                  | sndSecure -> notify (CON pqEncryption) >> setStatus Active
+                  | senderCanSecure queueMode -> notify (CON pqEncryption) >> setStatus Active
                   | otherwise -> setStatus Confirmed
                 AM_CONN_INFO_REPLY -> setStatus Confirmed
                 AM_RATCHET_INFO -> pure ()
@@ -1727,7 +1913,8 @@ switchDuplexConnection c (DuplexConnection cData@ConnData {connId, userId} rqs s
   -- try to get the server that is different from all queues, or at least from the primary rcv queue
   srvAuth@(ProtoServerWithAuth srv _) <- getNextSMPServer c userId $ map qServer (L.toList rqs) <> map qServer (L.toList sqs)
   srv' <- if srv == server then getNextSMPServer c userId [server] else pure srvAuth
-  (q, qUri, tSess, sessId) <- newRcvQueue c userId connId srv' clientVRange SMSubscribe False
+  -- TODO [notifications] send correct NTF credentials here
+  (q, qUri, tSess, sessId) <- newRcvQueue c userId connId srv' clientVRange SCMInvitation SMSubscribe -- Nothing
   let rq' = (q :: NewRcvQueue) {primary = True, dbReplaceQueueId = Just dbQueueId}
   rq'' <- withStore c $ \db -> addConnRcvQueue db connId rq'
   lift $ addNewQueueSubscription c rq'' tSess sessId
@@ -2396,7 +2583,7 @@ processSMPTransmissions c@AgentClient {subQ} (tSess@(userId, srv, _), _v, sessId
       mapM_ (atomically . writeTBQueue subQ) . reverse =<< readTVarIO pending
     processSMP :: forall c. RcvQueue -> Connection c -> ConnData -> BrokerMsg -> TVar [ATransmission] -> AM ()
     processSMP
-      rq@RcvQueue {rcvId = rId, sndSecure, e2ePrivKey, e2eDhSecret, status, smpClientVersion = agreedClientVerion}
+      rq@RcvQueue {rcvId = rId, queueMode, e2ePrivKey, e2eDhSecret, status, smpClientVersion = agreedClientVerion}
       conn
       cData@ConnData {connId, connAgentVersion = agreedAgentVersion, ratchetSyncState = rss}
       smpMsg
@@ -2425,7 +2612,7 @@ processSMPTransmissions c@AgentClient {subQ} (tSess@(userId, srv, _), _v, sessId
                       (SMP.PHConfirmation senderKey, AgentConfirmation {e2eEncryption_, encConnInfo, agentVersion}) ->
                         smpConfirmation srvMsgId conn (Just senderKey) e2ePubKey e2eEncryption_ encConnInfo phVer agentVersion >> ack
                       (SMP.PHEmpty, AgentConfirmation {e2eEncryption_, encConnInfo, agentVersion})
-                        | sndSecure -> smpConfirmation srvMsgId conn Nothing e2ePubKey e2eEncryption_ encConnInfo phVer agentVersion >> ack
+                        | senderCanSecure queueMode -> smpConfirmation srvMsgId conn Nothing e2ePubKey e2eEncryption_ encConnInfo phVer agentVersion >> ack
                         | otherwise -> prohibited "handshake: missing sender key" >> ack
                       (SMP.PHEmpty, AgentInvitation {connReq, connInfo}) ->
                         smpInvitation srvMsgId conn connReq connInfo >> ack
@@ -2751,7 +2938,7 @@ processSMPTransmissions c@AgentClient {subQ} (tSess@(userId, srv, _), _v, sessId
                     let (delSqs, keepSqs) = L.partition ((Just dbQueueId ==) . dbReplaceQId) sqs
                     case L.nonEmpty keepSqs of
                       Just sqs' -> do
-                        (sq_@SndQueue {sndPublicKey}, dhPublicKey) <- lift $ newSndQueue userId connId qInfo
+                        (sq_@SndQueue {sndPublicKey}, dhPublicKey) <- lift $ newSndQueue userId connId qInfo Nothing
                         sq2 <- withStore c $ \db -> do
                           liftIO $ mapM_ (deleteConnSndQueue db connId) delSqs
                           addConnSndQueue db connId (sq_ :: NewSndQueue) {primary = True, dbReplaceQueueId = Just dbQueueId}
@@ -2943,7 +3130,7 @@ connectReplyQueues c cData@ConnData {userId, connId} ownConnInfo sq_ (qInfo :| _
       enqueueConfirmation c cData sq' ownConnInfo Nothing
       where
         upgradeConn = do
-          (sq, _) <- lift $ newSndQueue userId connId qInfo'
+          (sq, _) <- lift $ newSndQueue userId connId qInfo' Nothing
           withStore c $ \db -> upgradeRcvConnToDuplex db connId sq
 
 secureConfirmQueueAsync :: AgentClient -> ConnData -> SndQueue -> SMPServerWithAuth -> ConnInfo -> Maybe (CR.SndE2ERatchetParams 'C.X448) -> SubscriptionMode -> AM SndQueueSecured
@@ -2973,7 +3160,7 @@ secureConfirmQueue c cData@ConnData {connId, connAgentVersion, pqSupport} sq srv
         pure . smpEncode $ AgentConfirmation {agentVersion = connAgentVersion, e2eEncryption_, encConnInfo}
 
 agentSecureSndQueue :: AgentClient -> ConnData -> SndQueue -> AM SndQueueSecured
-agentSecureSndQueue c ConnData {connAgentVersion} sq@SndQueue {sndSecure, status}
+agentSecureSndQueue c ConnData {connAgentVersion} sq@SndQueue {queueMode, status}
   | sndSecure && status == New = do
       secureSndQueue c sq
       withStore' c $ \db -> setSndQueueStatus db sq Secured
@@ -2982,6 +3169,7 @@ agentSecureSndQueue c ConnData {connAgentVersion} sq@SndQueue {sndSecure, status
   | sndSecure && status == Secured = pure initiatorRatchetOnConf
   | otherwise = pure False
   where
+    sndSecure = senderCanSecure queueMode
     initiatorRatchetOnConf = connAgentVersion >= ratchetOnConfSMPAgentVersion
 
 mkAgentConfirmation :: AgentClient -> ConnData -> SndQueue -> SMPServerWithAuth -> ConnInfo -> SubscriptionMode -> AM AgentMessage
@@ -3065,11 +3253,11 @@ agentRatchetDecrypt' g db connId rc encAgentMsg = do
   liftIO $ updateRatchet db connId rc' skippedDiff
   liftEither $ bimap (SEAgentError . cryptoError) (,CR.rcRcvKEM rc') agentMsgBody_
 
-newSndQueue :: UserId -> ConnId -> Compatible SMPQueueInfo -> AM' (NewSndQueue, C.PublicKeyX25519)
-newSndQueue userId connId (Compatible (SMPQueueInfo smpClientVersion SMPQueueAddress {smpServer, senderId, sndSecure, dhPublicKey = rcvE2ePubDhKey})) = do
+newSndQueue :: UserId -> ConnId -> Compatible SMPQueueInfo -> Maybe (C.AAuthKeyPair) -> AM' (NewSndQueue, C.PublicKeyX25519)
+newSndQueue userId connId (Compatible (SMPQueueInfo smpClientVersion SMPQueueAddress {smpServer, senderId, queueMode, dhPublicKey = rcvE2ePubDhKey})) sndKeys_ = do
   C.AuthAlg a <- asks $ sndAuthAlg . config
   g <- asks random
-  (sndPublicKey, sndPrivateKey) <- atomically $ C.generateAuthKeyPair a g
+  (sndPublicKey, sndPrivateKey) <- maybe (atomically $ C.generateAuthKeyPair a g) pure sndKeys_
   (e2ePubKey, e2ePrivKey) <- atomically $ C.generateKeyPair g
   let sq =
         SndQueue
@@ -3077,12 +3265,13 @@ newSndQueue userId connId (Compatible (SMPQueueInfo smpClientVersion SMPQueueAdd
             connId,
             server = smpServer,
             sndId = senderId,
-            sndSecure,
+            queueMode,
             sndPublicKey,
             sndPrivateKey,
             e2eDhSecret = C.dh' rcvE2ePubDhKey e2ePrivKey,
             e2ePubKey = Just e2ePubKey,
-            status = New,
+            -- setting status to Secured prevents SKEY when queue was already secured with LKEY
+            status = if isJust sndKeys_ then Secured else New,
             dbQueueId = DBNewQueue,
             primary = True,
             dbReplaceQueueId = Nothing,
diff --git a/src/Simplex/Messaging/Agent/Client.hs b/src/Simplex/Messaging/Agent/Client.hs
index 37f01752fd..240b25f7e2 100644
--- a/src/Simplex/Messaging/Agent/Client.hs
+++ b/src/Simplex/Messaging/Agent/Client.hs
@@ -26,6 +26,8 @@ module Simplex.Messaging.Agent.Client
   ( AgentClient (..),
     ProtocolTestFailure (..),
     ProtocolTestStep (..),
+    ClntQueueReqData (..),
+    CQRData (..),
     newAgentClient,
     withConnLock,
     withConnLocks,
@@ -43,6 +45,7 @@ module Simplex.Messaging.Agent.Client
     runNTFServerTest,
     getXFTPWorkPath,
     newRcvQueue,
+    newRcvQueue_,
     subscribeQueues,
     getQueueMessage,
     decryptSMPMessage,
@@ -57,6 +60,10 @@ module Simplex.Messaging.Agent.Client
     serverHostError,
     secureQueue,
     secureSndQueue,
+    addQueueLink,
+    deleteQueueLink,
+    secureGetQueueLink,
+    getQueueLink,
     enableQueueNotifications,
     EnableQueueNtfReq (..),
     enableQueuesNtfs,
@@ -256,22 +263,24 @@ import Simplex.Messaging.Protocol
     RcvNtfPublicDhKey,
     SMPMsgMeta (..),
     SProtocolType (..),
-    SenderCanSecure,
     SndPublicAuthKey,
     SubscriptionMode (..),
+    QueueReqData (..),
+    QueueLinkData,
     UserProtocol,
     VersionRangeSMPC,
     VersionSMPC,
     XFTPServer,
     XFTPServerWithAuth,
     pattern NoEntity,
+    senderCanSecure,
   )
 import qualified Simplex.Messaging.Protocol as SMP
 import Simplex.Messaging.Server.QueueStore.QueueInfo
 import Simplex.Messaging.Session
 import Simplex.Messaging.TMap (TMap)
 import qualified Simplex.Messaging.TMap as TM
-import Simplex.Messaging.Transport (SMPVersion, SessionId, THandleParams (sessionId), TransportError (..))
+import Simplex.Messaging.Transport (SMPVersion, SessionId, THandleParams (sessionId, thVersion), TransportError (..), TransportPeer (..), sndAuthKeySMPVersion, shortLinksSMPVersion)
 import Simplex.Messaging.Transport.Client (TransportHost (..))
 import Simplex.Messaging.Util
 import Simplex.Messaging.Version
@@ -1056,7 +1065,7 @@ withSMPClient c q cmdStr action = do
 
 sendOrProxySMPMessage :: AgentClient -> UserId -> SMPServer -> ConnId -> ByteString -> Maybe SMP.SndPrivateAuthKey -> SMP.SenderId -> MsgFlags -> SMP.MsgBody -> AM (Maybe SMPServer)
 sendOrProxySMPMessage c userId destSrv connId cmdStr spKey_ senderId msgFlags msg =
-  sendOrProxySMPCommand c userId destSrv connId cmdStr senderId sendViaProxy sendDirectly
+  fst <$> sendOrProxySMPCommand c userId destSrv connId cmdStr senderId sendViaProxy sendDirectly
   where
     sendViaProxy smp proxySess = do
       atomically $ incSMPServerStat c userId destSrv sentViaProxyAttempts
@@ -1067,18 +1076,19 @@ sendOrProxySMPMessage c userId destSrv connId cmdStr spKey_ senderId msgFlags ms
       sendSMPMessage smp spKey_ senderId msgFlags msg
 
 sendOrProxySMPCommand ::
+  forall a.
   AgentClient ->
   UserId ->
   SMPServer ->
-  ConnId ->
-  ByteString ->
-  SMP.SenderId ->
-  (SMPClient -> ProxiedRelay -> ExceptT SMPClientError IO (Either ProxyClientError ())) ->
-  (SMPClient -> ExceptT SMPClientError IO ()) ->
-  AM (Maybe SMPServer)
-sendOrProxySMPCommand c userId destSrv@ProtocolServer {host = destHosts} connId cmdStr senderId sendCmdViaProxy sendCmdDirectly = do
+  ConnId -> -- session entity ID, for short links LinkId is used
+  ByteString -> 
+  SMP.EntityId -> -- sender or link ID
+  (SMPClient -> ProxiedRelay -> ExceptT SMPClientError IO (Either ProxyClientError a)) ->
+  (SMPClient -> ExceptT SMPClientError IO a) ->
+  AM (Maybe SMPServer, a)
+sendOrProxySMPCommand c userId destSrv@ProtocolServer {host = destHosts} connId cmdStr entId sendCmdViaProxy sendCmdDirectly = do
   tSess <- mkTransportSession c userId destSrv connId
-  ifM shouldUseProxy (sendViaProxy Nothing tSess) (sendDirectly tSess $> Nothing)
+  ifM shouldUseProxy (sendViaProxy Nothing tSess) ((Nothing,) <$> sendDirectly tSess)
   where
     shouldUseProxy = do
       cfg <- getNetworkConfig c
@@ -1096,13 +1106,13 @@ sendOrProxySMPCommand c userId destSrv@ProtocolServer {host = destHosts} connId
         SPFAllowProtected -> ipAddressProtected cfg destSrv
         SPFProhibit -> False
     unknownServer = liftIO $ maybe True (\srvs -> all (`S.notMember` knownHosts srvs) destHosts) <$> TM.lookupIO userId (smpServers c)
-    sendViaProxy :: Maybe SMPServerWithAuth -> SMPTransportSession -> AM (Maybe SMPServer)
+    sendViaProxy :: Maybe SMPServerWithAuth -> SMPTransportSession -> AM (Maybe SMPServer, a)
     sendViaProxy proxySrv_ destSess@(_, _, connId_) = do
-      r <- tryAgentError . withProxySession c proxySrv_ destSess senderId ("PFWD " <> cmdStr) $ \(SMPConnectedClient smp _, proxySess@ProxiedRelay {prBasicAuth}) -> do
+      r <- tryAgentError . withProxySession c proxySrv_ destSess entId ("PFWD " <> cmdStr) $ \(SMPConnectedClient smp _, proxySess@ProxiedRelay {prBasicAuth}) -> do
         r' <- liftClient SMP (clientServer smp) $ sendCmdViaProxy smp proxySess
         let proxySrv = protocolClientServer' smp
         case r' of
-          Right () -> pure $ Just proxySrv
+          Right r -> pure (Just proxySrv, r)
           Left proxyErr -> do
             case proxyErr of
               ProxyProtocolError (SMP.PROXY SMP.NO_SESSION) -> do
@@ -1136,18 +1146,17 @@ sendOrProxySMPCommand c userId destSrv@ProtocolServer {host = destHosts} connId
               sameClient smp' = sessionId (thParams smp) == sessionId (thParams smp')
               sameProxiedRelay proxySess' = prSessionId proxySess == prSessionId proxySess'
       case r of
-        Right r' -> do
+        Right r'@(srv_, _) -> do
           atomically $ incSMPServerStat c userId destSrv sentViaProxy
-          forM_ r' $ \proxySrv -> atomically $ incSMPServerStat c userId proxySrv sentProxied
+          forM_ srv_ $ \proxySrv -> atomically $ incSMPServerStat c userId proxySrv sentProxied
           pure r'
         Left e
-          | serverHostError e -> ifM directAllowed (sendDirectly destSess $> Nothing) (throwE e)
+          | serverHostError e -> ifM directAllowed ((Nothing,) <$> sendDirectly destSess) (throwE e)
           | otherwise -> throwE e
     sendDirectly tSess =
-      withLogClient_ c tSess (unEntityId senderId) ("SEND " <> cmdStr) $ \(SMPConnectedClient smp _) -> do
-        r <- tryAgentError $ liftClient SMP (clientServer smp) $ sendCmdDirectly smp
-        case r of
-          Right () -> atomically $ incSMPServerStat c userId destSrv sentDirect
+      withLogClient_ c tSess (unEntityId entId) ("SEND " <> cmdStr) $ \(SMPConnectedClient smp _) -> do
+        tryAgentError (liftClient SMP (clientServer smp) $ sendCmdDirectly smp) >>= \case
+          Right r -> r <$ atomically (incSMPServerStat c userId destSrv sentDirect)
           Left e -> throwE e
 
 ipAddressProtected :: NetworkConfig -> ProtocolServer p -> Bool
@@ -1222,11 +1231,12 @@ runSMPServerTest c userId (ProtoServerWithAuth srv auth) = do
         (sKey, spKey) <- atomically $ C.generateAuthKeyPair sa g
         (dhKey, _) <- atomically $ C.generateKeyPair g
         r <- runExceptT $ do
-          SMP.QIK {rcvId, sndId, sndSecure} <- liftError (testErr TSCreateQueue) $ createSMPQueue smp rKeys dhKey auth SMSubscribe True
+          -- TODO [notifications]
+          SMP.QIK {rcvId, sndId, queueMode} <- liftError (testErr TSCreateQueue) $ createSMPQueue smp Nothing rKeys dhKey auth SMSubscribe (QRMessaging Nothing) -- Nothing
           liftError (testErr TSSecureQueue) $
-            if sndSecure
-              then secureSndSMPQueue smp spKey sndId sKey
-              else secureSMPQueue smp rpKey rcvId sKey
+            case queueMode of
+              Just QMMessaging -> secureSndSMPQueue smp spKey sndId sKey
+              _ -> secureSMPQueue smp rpKey rcvId sKey
           liftError (testErr TSDeleteQueue) $ deleteSMPQueue smp rpKey rcvId
         ok <- tcpTimeout (networkConfig cfg) `timeout` closeProtocolClient smp
         pure $ either Just (const Nothing) r <|> maybe (Just (ProtocolTestFailure TSDisconnect $ BROKER addr TIMEOUT)) (const Nothing) ok
@@ -1333,19 +1343,42 @@ getSessionMode :: MonadIO m => AgentClient -> m TransportSessionMode
 getSessionMode = fmap sessionMode . getNetworkConfig
 {-# INLINE getSessionMode #-}
 
-newRcvQueue :: AgentClient -> UserId -> ConnId -> SMPServerWithAuth -> VersionRangeSMPC -> SubscriptionMode -> SenderCanSecure -> AM (NewRcvQueue, SMPQueueUri, SMPTransportSession, SessionId)
-newRcvQueue c userId connId (ProtoServerWithAuth srv auth) vRange subMode senderCanSecure = do
+-- TODO [notifications]
+newRcvQueue :: AgentClient -> UserId -> ConnId -> SMPServerWithAuth -> VersionRangeSMPC -> SConnectionMode c -> SubscriptionMode -> AM (NewRcvQueue, SMPQueueUri, SMPTransportSession, SessionId)
+newRcvQueue c userId connId srv vRange cMode subMode = do
+  let qrd = case cMode of SCMInvitation -> CQRMessaging Nothing; SCMContact -> CQRContact Nothing
+  e2eKeys <- atomically . C.generateKeyPair =<< asks random
+  newRcvQueue_ c userId connId srv vRange qrd subMode Nothing e2eKeys
+
+data ClntQueueReqData
+  = CQRMessaging (Maybe (CQRData (SMP.SenderId, QueueLinkData)))
+  | CQRContact (Maybe (CQRData (SMP.LinkId, (SMP.SenderId, QueueLinkData))))
+
+data CQRData r = CQRData
+  { linkKey :: LinkKey,
+    privSigKey :: C.PrivateKeyEd25519,
+    srvReq :: r
+  }
+
+queueReqData :: ClntQueueReqData -> QueueReqData
+queueReqData = \case
+  CQRMessaging d -> QRMessaging $ srvReq <$> d
+  CQRContact d -> QRContact $ srvReq <$> d
+
+newRcvQueue_ :: AgentClient -> UserId -> ConnId -> SMPServerWithAuth -> VersionRangeSMPC -> ClntQueueReqData -> SubscriptionMode -> Maybe C.CbNonce -> C.KeyPairX25519 -> AM (NewRcvQueue, SMPQueueUri, SMPTransportSession, SessionId)
+newRcvQueue_ c userId connId (ProtoServerWithAuth srv auth) vRange cqrd subMode nonce_ (e2eDhKey, e2ePrivKey) = do
   C.AuthAlg a <- asks (rcvAuthAlg . config)
   g <- asks random
   rKeys@(_, rcvPrivateKey) <- atomically $ C.generateAuthKeyPair a g
   (dhKey, privDhKey) <- atomically $ C.generateKeyPair g
-  (e2eDhKey, e2ePrivKey) <- atomically $ C.generateKeyPair g
   logServer "-->" c srv NoEntity "NEW"
   tSess <- mkTransportSession c userId srv connId
-  (sessId, QIK {rcvId, sndId, rcvPublicDhKey, sndSecure}) <-
+  -- TODO [notifications]
+  r@(thParams', QIK {rcvId, sndId, rcvPublicDhKey, queueMode}) <-
     withClient c tSess $ \(SMPConnectedClient smp _) ->
-      (sessionId $ thParams smp,) <$> createSMPQueue smp rKeys dhKey auth subMode senderCanSecure
+      (thParams smp,) <$> createSMPQueue smp nonce_ rKeys dhKey auth subMode (queueReqData cqrd)
   liftIO . logServer "<--" c srv NoEntity $ B.unwords ["IDS", logSecret rcvId, logSecret sndId]
+  shortLink <- mkShortLinkCreds r
   let rq =
         RcvQueue
           { userId,
@@ -1357,7 +1390,8 @@ newRcvQueue c userId connId (ProtoServerWithAuth srv auth) vRange subMode sender
             e2ePrivKey,
             e2eDhSecret = Nothing,
             sndId,
-            sndSecure,
+            queueMode,
+            shortLink,
             status = New,
             dbQueueId = DBNewQueue,
             primary = True,
@@ -1367,8 +1401,35 @@ newRcvQueue c userId connId (ProtoServerWithAuth srv auth) vRange subMode sender
             clientNtfCreds = Nothing,
             deleteErrors = 0
           }
-      qUri = SMPQueueUri vRange $ SMPQueueAddress srv sndId e2eDhKey sndSecure
-  pure (rq, qUri, tSess, sessId)
+      qUri = SMPQueueUri vRange $ SMPQueueAddress srv sndId e2eDhKey queueMode
+  pure (rq, qUri, tSess, sessionId thParams')
+  where
+    mkShortLinkCreds :: (THandleParams SMPVersion 'TClient, QueueIdsKeys) -> AM (Maybe ShortLinkCreds)
+    mkShortLinkCreds (thParams', QIK {sndId, queueMode, linkId}) = case (cqrd, queueMode) of
+      (CQRMessaging ld, Just QMMessaging) -> 
+        withLinkData ld $ \lnkId CQRData {linkKey, privSigKey, srvReq = (sndId', d)} ->
+          if sndId == sndId'
+            then pure $ Just $ ShortLinkCreds lnkId linkKey privSigKey (fst d)
+            else newErr "different sender ID"
+      (CQRContact ld, Just QMContact) ->
+        withLinkData ld $ \lnkId CQRData {linkKey, privSigKey, srvReq = (lnkId', (sndId', d))} ->
+          if sndId == sndId' && lnkId == lnkId'
+            then pure $ Just $ ShortLinkCreds lnkId linkKey privSigKey (fst d)
+            else newErr "different sender or link IDs"
+      (_, Nothing) -> case linkId of
+        Nothing | v < sndAuthKeySMPVersion -> pure Nothing
+        _ -> newErr "unexpected link ID"
+      _ -> newErr "unexpected queue mode"
+      where
+        v = thVersion thParams'
+        withLinkData :: Maybe d -> (SMP.LinkId -> d -> AM (Maybe ShortLinkCreds)) -> AM (Maybe ShortLinkCreds)
+        withLinkData ld_ mkLink = case (ld_, linkId) of
+          (Just ld, Just lnkId) -> mkLink lnkId ld
+          (Just _, Nothing) | v < shortLinksSMPVersion -> pure Nothing
+          (Nothing, Nothing) -> pure Nothing
+          _ -> newErr "unexpected or absent link ID"
+        newErr :: String -> AM (Maybe ShortLinkCreds)
+        newErr = throwE . BROKER (B.unpack $ strEncode srv) . UNEXPECTED . ("Create queue: " <>)
 
 processSubResult :: AgentClient -> SessionId -> RcvQueue -> Either SMPClientError () -> STM ()
 processSubResult c sessId rq@RcvQueue {userId, server, connId} = \case
@@ -1558,8 +1619,8 @@ logSecret' = B64.encode . B.take 3
 {-# INLINE logSecret' #-}
 
 sendConfirmation :: AgentClient -> SndQueue -> ByteString -> AM (Maybe SMPServer)
-sendConfirmation c sq@SndQueue {userId, server, connId, sndId, sndSecure, sndPublicKey, sndPrivateKey, e2ePubKey = e2ePubKey@Just {}} agentConfirmation = do
-  let (privHdr, spKey) = if sndSecure then (SMP.PHEmpty, Just sndPrivateKey) else (SMP.PHConfirmation sndPublicKey, Nothing)
+sendConfirmation c sq@SndQueue {userId, server, connId, sndId, queueMode, sndPublicKey, sndPrivateKey, e2ePubKey = e2ePubKey@Just {}} agentConfirmation = do
+  let (privHdr, spKey) = if senderCanSecure queueMode then (SMP.PHEmpty, Just sndPrivateKey) else (SMP.PHConfirmation sndPublicKey, Nothing)
       clientMsg = SMP.ClientMessage privHdr agentConfirmation
   msg <- agentCbEncrypt sq e2ePubKey $ smpEncode clientMsg
   sendOrProxySMPMessage c userId server connId "<CONF>" spKey sndId (MsgFlags {notification = True}) msg
@@ -1611,6 +1672,28 @@ secureSndQueue c SndQueue {userId, connId, server, sndId, sndPrivateKey, sndPubl
     secureViaProxy smp proxySess = proxySecureSndSMPQueue smp proxySess sndPrivateKey sndId sndPublicKey
     secureDirectly smp = secureSndSMPQueue smp sndPrivateKey sndId sndPublicKey
 
+addQueueLink :: AgentClient -> RcvQueue -> SMP.LinkId -> QueueLinkData -> AM ()
+addQueueLink c rq@RcvQueue {rcvId, rcvPrivateKey} lnkId d =
+  withSMPClient c rq "LSET" $ \smp -> addSMPQueueLink smp rcvPrivateKey rcvId lnkId d
+
+deleteQueueLink :: AgentClient -> RcvQueue -> AM ()
+deleteQueueLink c rq@RcvQueue {rcvId, rcvPrivateKey} =
+  withSMPClient c rq "LDEL" $ \smp -> deleteSMPQueueLink smp rcvPrivateKey rcvId
+
+secureGetQueueLink :: AgentClient -> UserId -> InvShortLink -> AM (SMP.SenderId, QueueLinkData)
+secureGetQueueLink c userId InvShortLink {server, linkId, sndPrivateKey, sndPublicKey} =
+  snd <$> sendOrProxySMPCommand c userId server (unEntityId linkId) "LKEY <key>" linkId secureGetViaProxy secureGetDirectly
+  where
+    secureGetViaProxy smp proxySess = proxySecureGetSMPQueueLink smp proxySess sndPrivateKey linkId sndPublicKey
+    secureGetDirectly smp = secureGetSMPQueueLink smp sndPrivateKey linkId sndPublicKey
+
+getQueueLink :: AgentClient -> UserId -> SMPServer -> SMP.LinkId -> AM (SMP.SenderId, QueueLinkData)
+getQueueLink c userId server lnkId =
+  snd <$> sendOrProxySMPCommand c userId server (unEntityId lnkId) "LGET" lnkId getViaProxy getDirectly
+  where
+    getViaProxy smp proxySess = proxyGetSMPQueueLink smp proxySess lnkId
+    getDirectly smp = getSMPQueueLink smp lnkId
+
 enableQueueNotifications :: AgentClient -> RcvQueue -> SMP.NtfPublicAuthKey -> SMP.RcvNtfPublicDhKey -> AM (SMP.NotifierId, SMP.RcvNtfPublicDhKey)
 enableQueueNotifications c rq@RcvQueue {rcvId, rcvPrivateKey} notifierKey rcvNtfPublicDhKey =
   withSMPClient c rq "NKEY <nkey>" $ \smp ->
diff --git a/src/Simplex/Messaging/Agent/Protocol.hs b/src/Simplex/Messaging/Agent/Protocol.hs
index 4c6c75d8c4..43cceb376e 100644
--- a/src/Simplex/Messaging/Agent/Protocol.hs
+++ b/src/Simplex/Messaging/Agent/Protocol.hs
@@ -1,8 +1,10 @@
 {-# LANGUAGE DataKinds #-}
 {-# LANGUAGE DeriveAnyClass #-}
+{-# LANGUAGE DerivingStrategies #-}
 {-# LANGUAGE DuplicateRecordFields #-}
 {-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE GADTs #-}
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
 {-# LANGUAGE LambdaCase #-}
 {-# LANGUAGE MultiParamTypeClasses #-}
 {-# LANGUAGE NamedFieldPuns #-}
@@ -19,6 +21,7 @@
 {-# LANGUAGE TypeFamilies #-}
 {-# LANGUAGE UndecidableInstances #-}
 {-# OPTIONS_GHC -fno-warn-unticked-promoted-constructors #-}
+{-# OPTIONS_GHC -fno-warn-ambiguous-fields #-}
 
 -- |
 -- Module      : Simplex.Messaging.Agent.Protocol
@@ -100,17 +103,31 @@ module Simplex.Messaging.Agent.Protocol
     ConnectionMode (..),
     SConnectionMode (..),
     AConnectionMode (..),
-    cmInvitation,
-    cmContact,
     ConnectionModeI (..),
     ConnectionRequestUri (..),
     AConnectionRequestUri (..),
     ConnReqUriData (..),
     CRClientData,
     ServiceScheme,
+    FixedLinkData (..),
+    ConnLinkData (..),
+    OwnerAuth (..),
+    OwnerId,
+    ConnectionLink (..),
+    AConnectionLink (..),
+    ConnShortLink (..),
+    AConnShortLink (..),
+    CreatedConnLink (..),
+    ACreatedConnLink (..),
+    ContactConnType (..),
+    ShortLinkScheme (..),
+    LinkKey (..),
     sameConnReqContact,
+    sameShortLinkContact,
     simplexChat,
     connReqUriP',
+    simplexConnReqUri,
+    simplexShortLink,
     AgentErrorType (..),
     CommandErrorType (..),
     ConnectionErrorType (..),
@@ -143,16 +160,23 @@ module Simplex.Messaging.Agent.Protocol
     aMessageType,
     extraSMPServerHosts,
     updateSMPServerHosts,
+    shortenShortLink,
+    restoreShortLink,
+    linkUserData,
   )
 where
 
 import Control.Applicative (optional, (<|>))
-import Data.Aeson (FromJSON (..), ToJSON (..))
+import Data.Aeson (FromJSON (..), ToJSON (..), Value (..), (.:), (.:?))
 import qualified Data.Aeson.TH as J
+import qualified Data.Aeson.Types as JT
 import Data.Attoparsec.ByteString.Char8 (Parser)
 import qualified Data.Attoparsec.ByteString.Char8 as A
+import qualified Data.ByteString.Base64.URL as B64
 import Data.ByteString.Char8 (ByteString)
 import qualified Data.ByteString.Char8 as B
+import Data.Char (toLower, toUpper)
+import Data.Foldable (find)
 import Data.Functor (($>))
 import Data.Int (Int64)
 import Data.Kind (Type)
@@ -166,7 +190,7 @@ import Data.Text.Encoding (decodeLatin1, encodeUtf8)
 import Data.Time.Clock (UTCTime)
 import Data.Time.Clock.System (SystemTime)
 import Data.Type.Equality
-import Data.Typeable ()
+import Data.Typeable (Typeable)
 import Data.Word (Word16, Word32)
 import Simplex.Messaging.Agent.Store.DB (Binary (..), FromField (..), ToField (..), blobFieldDecoder, fromTextField_)
 import Simplex.FileTransfer.Description
@@ -198,6 +222,7 @@ import Simplex.Messaging.Protocol
     MsgId,
     NMsgMeta,
     ProtocolServer (..),
+    QueueMode (..),
     SMPClientVersion,
     SMPServer,
     SMPServerWithAuth,
@@ -213,6 +238,8 @@ import Simplex.Messaging.Protocol
     sameSrvAddr,
     sndAuthKeySMPClientVersion,
     srvHostnamesSMPClientVersion,
+    shortLinksSMPClientVersion,
+    senderCanSecure,
     pattern ProtoServerWithAuth,
     pattern SMPServer,
   )
@@ -232,6 +259,7 @@ import UnliftIO.Exception (Exception)
 -- 4 - delivery receipts (7/13/2023)
 -- 5 - post-quantum double ratchet (3/14/2024)
 -- 6 - secure reply queues with provided keys (6/14/2024)
+-- 7 - initialize ratchet on processing confirmation (7/18/2024)
 
 data SMPAgentVersion
 
@@ -676,21 +704,17 @@ data AConnectionMode = forall m. ConnectionModeI m => ACM (SConnectionMode m)
 instance Eq AConnectionMode where
   ACM m == ACM m' = isJust $ testEquality m m'
 
-cmInvitation :: AConnectionMode
-cmInvitation = ACM SCMInvitation
-
-cmContact :: AConnectionMode
-cmContact = ACM SCMContact
-
 deriving instance Show AConnectionMode
 
 connMode :: SConnectionMode m -> ConnectionMode
 connMode SCMInvitation = CMInvitation
 connMode SCMContact = CMContact
+{-# INLINE connMode #-}
 
 connMode' :: ConnectionMode -> AConnectionMode
-connMode' CMInvitation = cmInvitation
-connMode' CMContact = cmContact
+connMode' CMInvitation = ACM SCMInvitation
+connMode' CMContact = ACM SCMContact
+{-# INLINE connMode' #-}
 
 class ConnectionModeI (m :: ConnectionMode) where sConnectionMode :: SConnectionMode m
 
@@ -1042,6 +1066,36 @@ instance ConnectionModeI m => StrEncoding (ConnectionRequestUri m) where
                 <> maybe [] (\cd -> [("data", encodeUtf8 cd)]) crClientData
   strP = connReqUriP' (Just SSSimplex)
 
+instance ConnectionModeI m => Encoding (ConnectionRequestUri m) where
+  smpEncode = \case
+    CRInvitationUri crData e2eParams -> smpEncode (CMInvitation, crData, e2eParams)
+    CRContactUri crData -> smpEncode (CMContact, crData)
+  smpP = (\(ACR _ cr) -> checkConnMode cr) <$?> smpP
+  {-# INLINE smpP #-}
+
+instance Encoding AConnectionRequestUri where
+  smpEncode (ACR _ cr) = smpEncode cr
+  {-# INLINE smpEncode #-}
+  smpP =
+    smpP >>= \case
+      CMInvitation -> ACR SCMInvitation <$> (CRInvitationUri <$> smpP <*> smpP)
+      CMContact -> ACR SCMContact . CRContactUri <$> smpP
+
+instance Encoding ConnReqUriData where
+  smpEncode ConnReqUriData {crAgentVRange, crSmpQueues, crClientData} =
+    smpEncode (crAgentVRange, crSmpQueues, Large . encodeUtf8 <$> crClientData)
+  smpP = do
+    (crAgentVRange, smpQueues, clientData) <- smpP
+    -- This patch to compensate for the fact that queueMode QMContact won't be included in queue encoding,
+    -- until min SMP client version is >= 3 (sndAuthKeySMPClientVersion).
+    -- This is possible because SMP encoding of ConnReqUriData was not used prior to SMP client version 4.
+    let crSmpQueues = L.map patchQueueMode smpQueues
+    pure ConnReqUriData {crScheme = SSSimplex, crAgentVRange, crSmpQueues, crClientData = safeDecodeUtf8 . unLarge <$> clientData}
+    where
+      patchQueueMode q@SMPQueueUri {queueAddress = a} = case a of
+        SMPQueueAddress {queueMode = Nothing} -> q {queueAddress = a {queueMode = Just QMContact}} :: SMPQueueUri
+        _ -> q
+
 connReqUriP' :: forall m. ConnectionModeI m => Maybe ServiceScheme -> Parser (ConnectionRequestUri m)
 connReqUriP' overrideScheme = do
   ACR m cr <- connReqUriP overrideScheme
@@ -1091,6 +1145,13 @@ instance ToJSON AConnectionRequestUri where
   toJSON = strToJSON
   toEncoding = strToJEncoding
 
+instance ConnectionModeI m => FromJSON (ConnShortLink m) where
+  parseJSON = strParseJSON "ConnShortLink"
+
+instance ConnectionModeI m => ToJSON (ConnShortLink m) where
+  toJSON = strToJSON
+  toEncoding = strToJEncoding
+
 -- debug :: Show a => String -> a -> a
 -- debug name value = unsafePerformIO (putStrLn $ name <> ": " <> show value) `seq` value
 -- {-# INLINE debug #-}
@@ -1105,6 +1166,16 @@ instance StrEncoding AConnectionMode where
   strEncode (ACM cMode) = strEncode $ connMode cMode
   strP = connMode' <$> strP
 
+instance Encoding ConnectionMode where
+  smpEncode = \case
+    CMInvitation -> "I"
+    CMContact -> "C"
+  smpP =
+    A.anyChar >>= \case
+      'I' -> pure CMInvitation
+      'C' -> pure CMContact
+      _ -> fail "bad connection mode"
+
 connModeT :: Text -> Maybe ConnectionMode
 connModeT = \case
   "INV" -> Just CMInvitation
@@ -1152,16 +1223,20 @@ data SMPQueueInfo = SMPQueueInfo {clientVersion :: VersionSMPC, queueAddress ::
   deriving (Eq, Show)
 
 instance Encoding SMPQueueInfo where
-  smpEncode (SMPQueueInfo clientVersion SMPQueueAddress {smpServer, senderId, dhPublicKey, sndSecure})
-    | clientVersion >= sndAuthKeySMPClientVersion && sndSecure = smpEncode (clientVersion, smpServer, senderId, dhPublicKey, sndSecure)
-    | clientVersion > initialSMPClientVersion = smpEncode (clientVersion, smpServer, senderId, dhPublicKey)
+  smpEncode (SMPQueueInfo clientVersion SMPQueueAddress {smpServer, senderId, dhPublicKey, queueMode})
+    | clientVersion >= shortLinksSMPClientVersion = addrEnc <> maybe "" smpEncode queueMode
+    | clientVersion >= sndAuthKeySMPClientVersion && sndSecure = addrEnc <> smpEncode sndSecure
+    | clientVersion > initialSMPClientVersion = addrEnc
     | otherwise = smpEncode clientVersion <> legacyEncodeServer smpServer <> smpEncode (senderId, dhPublicKey)
+    where
+      addrEnc = smpEncode (clientVersion, smpServer, senderId, dhPublicKey)
+      sndSecure = senderCanSecure queueMode
   smpP = do
     clientVersion <- smpP
     smpServer <- if clientVersion > initialSMPClientVersion then smpP else updateSMPServerHosts <$> legacyServerP
     (senderId, dhPublicKey) <- smpP
-    sndSecure <- fromMaybe False <$> optional smpP
-    pure $ SMPQueueInfo clientVersion SMPQueueAddress {smpServer, senderId, dhPublicKey, sndSecure}
+    queueMode <- queueModeP
+    pure $ SMPQueueInfo clientVersion SMPQueueAddress {smpServer, senderId, dhPublicKey, queueMode}
 
 -- This instance seems contrived and there was a temptation to split a common part of both types.
 -- But this is created to allow backward and forward compatibility where SMPQueueUri
@@ -1188,7 +1263,7 @@ data SMPQueueAddress = SMPQueueAddress
   { smpServer :: SMPServer,
     senderId :: SMP.SenderId,
     dhPublicKey :: C.PublicKeyX25519,
-    sndSecure :: Bool
+    queueMode :: Maybe QueueMode
   }
   deriving (Eq, Show)
 
@@ -1215,42 +1290,60 @@ sameQAddress (srv, qId) (srv', qId') = sameSrvAddr srv srv' && qId == qId'
 {-# INLINE sameQAddress #-}
 
 instance StrEncoding SMPQueueUri where
-  strEncode (SMPQueueUri vr SMPQueueAddress {smpServer = srv, senderId = qId, dhPublicKey, sndSecure})
+  strEncode (SMPQueueUri vr SMPQueueAddress {smpServer = srv, senderId = qId, dhPublicKey, queueMode})
     | minVersion vr >= srvHostnamesSMPClientVersion = strEncode srv <> "/" <> strEncode qId <> "#/?" <> query queryParams
     | otherwise = legacyStrEncodeServer srv <> "/" <> strEncode qId <> "#/?" <> query (queryParams <> srvParam)
     where
       query = strEncode . QSP QEscape
-      queryParams = [("v", strEncode vr), ("dh", strEncode dhPublicKey)] <> [("k", "s") | sndSecure]
+      queryParams = [("v", strEncode vr), ("dh", strEncode dhPublicKey)] <> queueModeParam <> sndSecureParam
+        where
+          queueModeParam = case queueMode of
+            Just QMMessaging -> [("q", "m")]
+            Just QMContact -> [("q", "c")]
+            Nothing -> []
+          sndSecureParam = [("k", "s") | senderCanSecure queueMode && minVersion vr < shortLinksSMPClientVersion]
       srvParam = [("srv", strEncode $ TransportHosts_ hs) | not (null hs)]
       hs = L.tail $ host srv
   strP = do
     srv@ProtocolServer {host = h :| host} <- strP <* A.char '/'
     senderId <- strP <* optional (A.char '/') <* A.char '#'
-    (vr, hs, dhPublicKey, sndSecure) <- versioned <|> unversioned
+    (vr, hs, dhPublicKey, queueMode) <- versioned <|> unversioned
     let srv' = srv {host = h :| host <> hs}
         smpServer = if maxVersion vr < srvHostnamesSMPClientVersion then updateSMPServerHosts srv' else srv'
-    pure $ SMPQueueUri vr SMPQueueAddress {smpServer, senderId, dhPublicKey, sndSecure}
+    pure $ SMPQueueUri vr SMPQueueAddress {smpServer, senderId, dhPublicKey, queueMode}
     where
-      unversioned = (versionToRange initialSMPClientVersion,[],,False) <$> strP <* A.endOfInput
+      unversioned = (versionToRange initialSMPClientVersion,[],,Nothing) <$> strP <* A.endOfInput
       versioned = do
         dhKey_ <- optional strP
         query <- optional (A.char '/') *> A.char '?' *> strP
         vr <- queryParam "v" query
         dhKey <- maybe (queryParam "dh" query) pure dhKey_
         hs_ <- queryParam_ "srv" query
-        let sndSecure = queryParamStr "k" query == Just "s"
-        pure (vr, maybe [] thList_ hs_, dhKey, sndSecure)
+        let queueMode = case queryParamStr "q" query of
+              Just "m" -> Just QMMessaging
+              Just "c" -> Just QMContact
+              _ | queryParamStr "k" query == Just "s" -> Just QMMessaging
+              _ -> Nothing
+        pure (vr, maybe [] thList_ hs_, dhKey, queueMode)
 
 instance Encoding SMPQueueUri where
-  smpEncode (SMPQueueUri clientVRange SMPQueueAddress {smpServer, senderId, dhPublicKey, sndSecure})
-    | maxVersion clientVRange >= sndAuthKeySMPClientVersion && sndSecure =
-        smpEncode (clientVRange, smpServer, senderId, dhPublicKey, sndSecure)
-    | otherwise =
-        smpEncode (clientVRange, smpServer, senderId, dhPublicKey)
+  smpEncode (SMPQueueUri clientVRange@(VersionRange minV maxV) SMPQueueAddress {smpServer, senderId, dhPublicKey, queueMode})
+    -- The condition is for minVersion as earlier clients won't be able to support it.
+    -- The alternative would be to encode both queueMode and sndSecure
+    | minV >= shortLinksSMPClientVersion = addrEnc <> maybe "" smpEncode queueMode
+    -- Earlier versions won't be able to ignore sndSecure, so we don't include it when it is False
+    | minV >= sndAuthKeySMPClientVersion || (maxV >= sndAuthKeySMPClientVersion && sndSecure) = addrEnc <> smpEncode sndSecure
+    | otherwise = addrEnc
+    where
+      addrEnc = smpEncode (clientVRange, smpServer, senderId, dhPublicKey)
+      sndSecure = senderCanSecure queueMode
   smpP = do
     (clientVRange, smpServer, senderId, dhPublicKey) <- smpP
-    sndSecure <- fromMaybe False <$> optional smpP
-    pure $ SMPQueueUri clientVRange SMPQueueAddress {smpServer, senderId, dhPublicKey, sndSecure}
+    queueMode <- queueModeP
+    pure $ SMPQueueUri clientVRange SMPQueueAddress {smpServer, senderId, dhPublicKey, queueMode}
+
+queueModeP :: Parser (Maybe QueueMode)
+queueModeP = Just <$> smpP <|> optional ((\case True -> QMMessaging; _ -> QMContact) <$> smpP)
 
 data ConnectionRequestUri (m :: ConnectionMode) where
   CRInvitationUri :: ConnReqUriData -> RcvE2ERatchetParamsUri 'C.X448 -> ConnectionRequestUri CMInvitation
@@ -1258,6 +1351,11 @@ data ConnectionRequestUri (m :: ConnectionMode) where
   -- they are passed in AgentInvitation message
   CRContactUri :: ConnReqUriData -> ConnectionRequestUri CMContact
 
+simplexConnReqUri :: ConnectionRequestUri m -> ConnectionRequestUri m
+simplexConnReqUri = \case
+  CRInvitationUri crData e2eParams -> CRInvitationUri crData {crScheme = SSSimplex} e2eParams
+  CRContactUri crData -> CRContactUri crData {crScheme = SSSimplex}
+
 deriving instance Eq (ConnectionRequestUri m)
 
 deriving instance Show (ConnectionRequestUri m)
@@ -1271,12 +1369,229 @@ instance Eq AConnectionRequestUri where
 
 deriving instance Show AConnectionRequestUri
 
+data ShortLinkScheme = SLSSimplex | SLSServer deriving (Eq, Show)
+
+data ConnShortLink (m :: ConnectionMode) where
+  CSLInvitation :: ShortLinkScheme -> SMPServer -> SMP.LinkId -> LinkKey -> ConnShortLink 'CMInvitation
+  CSLContact :: ShortLinkScheme -> ContactConnType -> SMPServer -> LinkKey -> ConnShortLink 'CMContact
+
+deriving instance Eq (ConnShortLink m)
+
+deriving instance Show (ConnShortLink m)
+
+simplexShortLink :: ConnShortLink m -> ConnShortLink m
+simplexShortLink = \case
+  CSLInvitation _ srv lnkId k -> CSLInvitation SLSSimplex srv lnkId k
+  CSLContact _ ct srv k -> CSLContact SLSSimplex ct srv k
+
+newtype LinkKey = LinkKey ByteString -- sha3-256(fixed_data)
+  deriving (Eq, Show)
+  deriving newtype (FromField, StrEncoding)
+
+instance ToField LinkKey where toField (LinkKey s) = toField $ Binary s
+
+instance ConnectionModeI c => ToField (ConnectionLink c) where toField = toField . Binary . strEncode
+
+instance (Typeable c, ConnectionModeI c) => FromField (ConnectionLink c) where fromField = blobFieldDecoder strDecode
+
+instance ConnectionModeI c => ToField (ConnShortLink c) where toField = toField . Binary . strEncode
+
+instance (Typeable c, ConnectionModeI c) => FromField (ConnShortLink c) where fromField = blobFieldDecoder strDecode
+
+data ContactConnType = CCTContact | CCTChannel | CCTGroup deriving (Eq, Show)
+
+data AConnShortLink = forall m. ConnectionModeI m => ACSL (SConnectionMode m) (ConnShortLink m)
+
+data ConnectionLink m = CLFull (ConnectionRequestUri m) | CLShort (ConnShortLink m)
+  deriving (Eq, Show)
+
+data CreatedConnLink m = CCLink {connFullLink :: ConnectionRequestUri m, connShortLink :: Maybe (ConnShortLink m)}
+  deriving (Eq, Show)
+
+data ACreatedConnLink = forall m. ConnectionModeI m => ACCL (SConnectionMode m) (CreatedConnLink m)
+
+deriving instance Show ACreatedConnLink
+
+data AConnectionLink = forall m. ConnectionModeI m => ACL (SConnectionMode m) (ConnectionLink m)
+
+instance Eq AConnectionLink where
+  ACL m cl == ACL m' cl' = case testEquality m m' of
+    Just Refl -> cl == cl'
+    _ -> False
+
+deriving instance Show AConnectionLink
+
+instance ConnectionModeI m => StrEncoding (ConnectionLink m) where
+  strEncode = \case
+    CLFull cr -> strEncode cr
+    CLShort sl -> strEncode sl
+  strP = (\(ACL _ cl) -> checkConnMode cl) <$?> strP
+  {-# INLINE strP #-}
+
+instance StrEncoding AConnectionLink where
+  strEncode (ACL _ cl) = strEncode cl
+  {-# INLINE strEncode #-}
+  strP =
+    (\(ACR m cr) -> ACL m (CLFull cr)) <$> strP
+      <|> (\(ACSL m sl) -> ACL m (CLShort sl)) <$> strP
+
+instance ConnectionModeI m => ToJSON (ConnectionLink m) where
+  toEncoding = strToJEncoding
+  toJSON = strToJSON
+
+instance ConnectionModeI m => FromJSON (ConnectionLink m) where
+  parseJSON = strParseJSON "ConnectionLink"
+
+instance ToJSON AConnectionLink where
+  toEncoding = strToJEncoding
+  toJSON = strToJSON
+
+instance FromJSON AConnectionLink where
+  parseJSON = strParseJSON "AConnectionLink"
+
+instance ConnectionModeI m => StrEncoding (ConnShortLink m) where
+  strEncode = \case
+    CSLInvitation sch srv (SMP.EntityId lnkId) (LinkKey k) -> slEncode sch srv 'i' lnkId k
+    CSLContact sch ct srv (LinkKey k) -> slEncode sch srv (toLower $ ctTypeChar ct) "" k
+    where
+      slEncode sch (SMPServer (h :| hs) port (C.KeyHash kh)) linkType lnkId k =
+        B.concat [authority, "/", B.singleton linkType, "#", lnkIdStr, B64.encodeUnpadded k, queryStr]
+        where
+          (authority, paramHosts) = case sch of
+            SLSSimplex -> ("simplex:", h : hs)
+            SLSServer -> ("https://" <> strEncode h, hs)
+          lnkIdStr = if B.null lnkId then "" else B64.encodeUnpadded lnkId <> "/"
+          queryStr = if B.null query then "" else "?" <> query
+          query =
+            strEncode . QSP QEscape $
+              [("h", strEncode (TransportHosts_ paramHosts)) | not (null paramHosts)]
+                <> [("p", B.pack port) | not (null port)]
+                <> [("c", B64.encodeUnpadded kh) | not (B.null kh)]
+  strP = (\(ACSL _ l) -> checkConnMode l) <$?> strP
+  {-# INLINE strP #-}
+
+instance StrEncoding AConnShortLink where
+  strEncode (ACSL _ l) = strEncode l
+  {-# INLINE strEncode #-}
+  strP = do
+    (sch, h_) <- authorityP <* A.char '/'
+    ct_ <- contactTypeP <* optional (A.char '/') <* A.char '#'
+    case ct_ of
+      Nothing -> do
+        lnkId <- strP <* A.char '/'
+        k <- strP
+        srv <- serverQueryP h_
+        pure $ ACSL SCMInvitation $ CSLInvitation sch srv (SMP.EntityId lnkId) (LinkKey k)
+      Just ct -> do
+        k <- strP
+        srv <- serverQueryP h_
+        pure $ ACSL SCMContact $ CSLContact sch ct srv (LinkKey k)
+    where
+      authorityP =
+        "simplex:" $> (SLSSimplex, Nothing)
+          <|> "https://" *> ((SLSServer,) . Just <$> strP)
+          <|> fail "bad short link scheme"
+      contactTypeP = do
+        Just <$> (A.anyChar >>= ctTypeP . toUpper)        
+          <|> A.char 'i' $> Nothing
+          <|> fail "unknown short link type"
+      serverQueryP h_ =
+        optional (A.char '?' *> strP) >>= \case
+          Nothing -> maybe noServer (pure . SMPServerOnlyHost) h_
+          Just query -> do
+            hs <- maybe noServer pure . L.nonEmpty . maybe id (:) h_ . maybe [] thList_ =<< queryParam_ "h" query
+            p <- maybe "" show <$> queryParam_ @Word16 "p" query
+            kh <- fromMaybe (C.KeyHash "") <$> queryParam_ "c" query
+            pure $ SMPServer hs p kh
+      noServer = fail "short link without server"
+
+instance ConnectionModeI m => Encoding (ConnShortLink m) where
+  smpEncode = \case
+    CSLInvitation _ srv lnkId (LinkKey k) -> smpEncode (CMInvitation, srv, lnkId, k)
+    CSLContact _ ct srv (LinkKey k) -> smpEncode (CMContact, ctTypeChar ct, srv, k)
+  smpP = (\(ACSL _ l) -> checkConnMode l) <$?> smpP
+  {-# INLINE smpP #-}
+
+instance Encoding AConnShortLink where
+  smpEncode (ACSL _ l) = smpEncode l
+  {-# INLINE smpEncode #-}
+  smpP =
+    smpP >>= \case
+      CMInvitation -> do
+        (srv, lnkId, k) <- smpP
+        pure $ ACSL SCMInvitation $ CSLInvitation SLSServer srv lnkId (LinkKey k)
+      CMContact -> do
+        ct <- ctTypeP =<< A.anyChar
+        (srv, k) <- smpP
+        pure $ ACSL SCMContact $ CSLContact SLSServer ct srv (LinkKey k)
+
+ctTypeP :: Char -> Parser ContactConnType
+ctTypeP = \case
+  'A' -> pure CCTContact
+  'C' -> pure CCTChannel
+  'G' -> pure CCTGroup 
+  _ -> fail "unknown contact address type"
+{-# INLINE ctTypeP #-}
+
+ctTypeChar :: ContactConnType -> Char
+ctTypeChar = \case
+  CCTContact -> 'A'
+  CCTChannel -> 'C'
+  CCTGroup -> 'G'
+{-# INLINE ctTypeChar #-}
+
+-- the servers passed to this function should be all preset servers, not servers configured by the user.
+shortenShortLink :: NonEmpty SMPServer -> ConnShortLink m -> ConnShortLink m
+shortenShortLink presetSrvs = \case
+  CSLInvitation sch srv lnkId linkKey -> CSLInvitation sch (shortServer srv) lnkId linkKey
+  CSLContact sch ct srv linkKey -> CSLContact sch ct (shortServer srv) linkKey
+  where
+    shortServer srv@(SMPServer hs@(h :| _) p kh) =
+      if isPresetServer then SMPServerOnlyHost h else srv
+      where
+        isPresetServer = case findPresetServer srv presetSrvs of
+          Just (SMPServer hs' p' kh') ->
+            all (`elem` hs') hs
+              && (p == p' || (null p' && (p == "443" || p == "5223")))
+              && kh == kh'
+          Nothing -> False
+
+-- explicit bidirectional is used for ghc 8.10.7 compatibility, [h]/[] patterns are not reversible.
+pattern SMPServerOnlyHost :: TransportHost -> SMPServer
+pattern SMPServerOnlyHost h <- SMPServer [h] "" (C.KeyHash "")
+  where
+    SMPServerOnlyHost h = SMPServer [h] "" (C.KeyHash "")
+
+-- the servers passed to this function should be all preset servers, not servers configured by the user.
+restoreShortLink :: NonEmpty SMPServer -> ConnShortLink m -> ConnShortLink m
+restoreShortLink presetSrvs = \case
+  CSLInvitation sch srv lnkId linkKey -> CSLInvitation sch (fullServer srv) lnkId linkKey
+  CSLContact sch ct srv linkKey -> CSLContact sch ct (fullServer srv) linkKey
+  where
+    fullServer = \case
+      s@(SMPServerOnlyHost _) -> fromMaybe s $ findPresetServer s presetSrvs
+      s -> s
+
+findPresetServer :: SMPServer -> NonEmpty SMPServer -> Maybe SMPServer
+findPresetServer ProtocolServer {host = h :| _} = find (\ProtocolServer {host = h' :| _} -> h == h')
+{-# INLINE findPresetServer #-}
+
 sameConnReqContact :: ConnectionRequestUri 'CMContact -> ConnectionRequestUri 'CMContact -> Bool
 sameConnReqContact (CRContactUri ConnReqUriData {crSmpQueues = qs}) (CRContactUri ConnReqUriData {crSmpQueues = qs'}) =
   L.length qs == L.length qs' && all same (L.zip qs qs')
   where
     same (q, q') = sameQAddress (qAddress q) (qAddress q')
 
+sameShortLinkContact :: ConnShortLink 'CMContact -> ConnShortLink 'CMContact -> Bool
+sameShortLinkContact (CSLContact _ ct srv k) (CSLContact _ ct' srv' k') =
+  ct == ct' && sameSrvAddr srv srv' && k == k'
+
+checkConnMode :: forall t m m'. (ConnectionModeI m, ConnectionModeI m') => t m' -> Either String (t m)
+checkConnMode c = case testEquality (sConnectionMode @m) (sConnectionMode @m') of
+  Just Refl -> Right c
+  Nothing -> Left "bad connection mode"
+{-# INLINE checkConnMode #-}
+
 data ConnReqUriData = ConnReqUriData
   { crScheme :: ServiceScheme,
     crAgentVRange :: VersionRangeSMPA,
@@ -1287,6 +1602,86 @@ data ConnReqUriData = ConnReqUriData
 
 type CRClientData = Text
 
+data FixedLinkData c = FixedLinkData
+  { agentVRange :: VersionRangeSMPA,
+    rootKey :: C.PublicKeyEd25519,
+    connReq :: ConnectionRequestUri c
+  }
+
+data ConnLinkData c where
+  InvitationLinkData :: VersionRangeSMPA -> ConnInfo -> ConnLinkData 'CMInvitation
+  ContactLinkData ::
+    { agentVRange :: VersionRangeSMPA,
+      -- direct connection via connReq in fixed data is allowed.
+      direct :: Bool,
+      -- additional owner keys to sign changes of mutable data.
+      owners :: [OwnerAuth],
+      -- alternative addresses of chat relays that receive requests for this contact address.
+      relays :: [ConnShortLink 'CMContact],
+      userData :: ConnInfo
+    } -> ConnLinkData 'CMContact
+
+data AConnLinkData = forall m. ConnectionModeI m => ACLD (SConnectionMode m) (ConnLinkData m)
+
+linkUserData :: ConnLinkData c -> ConnInfo
+linkUserData = \case
+  InvitationLinkData _ d -> d
+  ContactLinkData {userData} -> userData
+
+type OwnerId = ByteString
+
+data OwnerAuth = OwnerAuth
+  { ownerId :: OwnerId, -- unique in the list, application specific - e.g., MemberId
+    ownerKey :: C.PublicKeyEd25519,
+    -- sender ID signed with ownerKey,
+    -- confirms that the owner accepts being the owner.
+    -- sender ID is used here as it is immutable for the queue, link data can be removed.
+    ownerSig :: C.Signature 'C.Ed25519,
+    -- null for root key authorization
+    authOwnerId :: OwnerId,
+    -- owner authorization, sig(ownerId || ownerKey, key(authOwnerId)),
+    -- where authOwnerId is either null for a root key or some other owner authorized by root key, etc.
+    -- Owner validation should detect and reject loops.
+    authOwnerSig :: C.Signature 'C.Ed25519
+  }
+
+instance Encoding OwnerAuth where
+  smpEncode OwnerAuth {ownerId, ownerKey, ownerSig, authOwnerId, authOwnerSig} =
+    smpEncode (ownerId, ownerKey, C.signatureBytes ownerSig, authOwnerId, C.signatureBytes authOwnerSig)
+  smpP = do
+    (ownerId, ownerKey, ownerSig, authOwnerId, authOwnerSig) <- smpP
+    pure OwnerAuth {ownerId, ownerKey, ownerSig, authOwnerId, authOwnerSig}
+
+instance ConnectionModeI c => Encoding (FixedLinkData c) where
+  smpEncode FixedLinkData {agentVRange, rootKey, connReq} =
+    smpEncode (agentVRange, rootKey, connReq)
+  smpP = do
+    (agentVRange, rootKey, connReq) <- smpP
+    pure FixedLinkData {agentVRange, rootKey, connReq}
+
+instance ConnectionModeI c => Encoding (ConnLinkData c) where
+  smpEncode = \case
+    InvitationLinkData vr userData -> smpEncode (CMInvitation, vr, userData)
+    ContactLinkData {agentVRange, direct, owners, relays, userData} ->
+      B.concat [smpEncode (CMContact, agentVRange, direct), smpEncodeList owners, smpEncodeList relays, smpEncode userData]
+  smpP = (\(ACLD _ d) -> checkConnMode d) <$?> smpP
+  {-# INLINE smpP #-}
+
+instance Encoding AConnLinkData where
+  smpEncode (ACLD _ d) = smpEncode d
+  {-# INLINE smpEncode #-}
+  smpP =
+    smpP >>= \case
+      CMInvitation -> do
+        (vr, userData) <- smpP
+        pure $ ACLD SCMInvitation $ InvitationLinkData vr userData
+      CMContact -> do
+        (agentVRange, direct) <- smpP
+        owners <- smpListP
+        relays <- smpListP
+        userData <- smpP
+        pure $ ACLD SCMContact ContactLinkData {agentVRange, direct, owners, relays, userData}
+
 -- | SMP queue status.
 data QueueStatus
   = -- | queue is created
@@ -1419,6 +1814,8 @@ data SMPAgentError
     A_PROHIBITED {prohibitedErr :: String}
   | -- | incompatible version of SMP client, agent or encryption protocols
     A_VERSION
+  | -- | failed signature, hash or senderId verification of retrieved link data
+    A_LINK {linkErr :: String}
   | -- | cannot decrypt message
     A_CRYPTO {cryptoErr :: AgentCryptoError}
   | -- | duplicate message - this error is detected by ratchet decryption - this message will be ignored and not shown
@@ -1531,3 +1928,22 @@ $(J.deriveJSON (sumTypeJSON id) ''AgentErrorType)
 $(J.deriveJSON (enumJSON $ dropPrefix "QD") ''QueueDirection)
 
 $(J.deriveJSON (enumJSON $ dropPrefix "SP") ''SwitchPhase)
+
+instance ConnectionModeI m => FromJSON (CreatedConnLink m) where
+  parseJSON = $(J.mkParseJSON defaultJSON ''CreatedConnLink)
+
+instance ConnectionModeI m => ToJSON (CreatedConnLink m) where
+  toEncoding = $(J.mkToEncoding defaultJSON ''CreatedConnLink)
+  toJSON = $(J.mkToJSON defaultJSON ''CreatedConnLink)
+
+instance FromJSON ACreatedConnLink where
+  parseJSON (Object v) = do
+    ACR m cReq <- v .: "connFullLink"
+    shortLink <- v .:? "connShortLink"
+    pure $ ACCL m $ CCLink cReq shortLink
+  parseJSON invalid =
+    JT.prependFailure "bad ACreatedConnLink, " (JT.typeMismatch "Object" invalid)
+
+instance ToJSON ACreatedConnLink where
+  toEncoding (ACCL _ ccLink) = toEncoding ccLink
+  toJSON (ACCL _ ccLink) = toJSON ccLink
diff --git a/src/Simplex/Messaging/Agent/Store.hs b/src/Simplex/Messaging/Agent/Store.hs
index 14e1f1fc83..79e194cf16 100644
--- a/src/Simplex/Messaging/Agent/Store.hs
+++ b/src/Simplex/Messaging/Agent/Store.hs
@@ -43,10 +43,10 @@ import Simplex.Messaging.Protocol
     NotifierId,
     NtfPrivateAuthKey,
     NtfPublicAuthKey,
+    QueueMode,
     RcvDhSecret,
     RcvNtfDhSecret,
     RcvPrivateAuthKey,
-    SenderCanSecure,
     SndPrivateAuthKey,
     SndPublicAuthKey,
     VersionSMPC,
@@ -92,7 +92,9 @@ data StoredRcvQueue (q :: QueueStored) = RcvQueue
     -- | sender queue ID
     sndId :: SMP.SenderId,
     -- | sender can secure the queue
-    sndSecure :: SenderCanSecure,
+    queueMode :: Maybe QueueMode,
+    -- | short link ID and credentials
+    shortLink :: Maybe ShortLinkCreds,
     -- | queue status
     status :: QueueStatus,
     -- | database queue ID (within connection)
@@ -110,6 +112,14 @@ data StoredRcvQueue (q :: QueueStored) = RcvQueue
   }
   deriving (Show)
 
+data ShortLinkCreds = ShortLinkCreds
+  { shortLinkId :: SMP.LinkId,
+    shortLinkKey :: LinkKey,
+    linkPrivSigKey :: C.PrivateKeyEd25519,
+    linkEncFixedData :: SMP.EncFixedDataBytes
+  }
+  deriving (Show)
+
 rcvQueueInfo :: RcvQueue -> RcvQueueInfo
 rcvQueueInfo rq@RcvQueue {server, rcvSwchStatus} =
   RcvQueueInfo {rcvServer = server, rcvSwitchStatus = rcvSwchStatus, canAbortSwitch = canAbortRcvSwitch rq}
@@ -137,6 +147,19 @@ data ClientNtfCreds = ClientNtfCreds
   }
   deriving (Show)
 
+-- This record is stored in inv_short_links table.
+-- It is needed only for 1-time invitation links because of "secure-on-read" property of link data,
+-- that prevents undetected access to link data from link observers.
+data InvShortLink = InvShortLink
+  { server :: SMPServer,
+    linkId :: SMP.LinkId,
+    linkKey :: LinkKey,
+    sndPrivateKey :: SndPrivateAuthKey, -- stored to allow retries
+    sndPublicKey :: SndPublicAuthKey,
+    sndId :: Maybe SMP.SenderId
+  }
+  deriving (Show)
+
 type SndQueue = StoredSndQueue 'QSStored
 
 type NewSndQueue = StoredSndQueue 'QSNew
@@ -149,7 +172,7 @@ data StoredSndQueue (q :: QueueStored) = SndQueue
     -- | sender queue ID
     sndId :: SMP.SenderId,
     -- | sender can secure the queue
-    sndSecure :: SenderCanSecure,
+    queueMode :: Maybe QueueMode,
     -- | key pair used by the sender to authorize transmissions
     -- TODO combine keys to key pair so that types match
     sndPublicKey :: SndPublicAuthKey,
diff --git a/src/Simplex/Messaging/Agent/Store/AgentStore.hs b/src/Simplex/Messaging/Agent/Store/AgentStore.hs
index a8c1e1fb00..2377875909 100644
--- a/src/Simplex/Messaging/Agent/Store/AgentStore.hs
+++ b/src/Simplex/Messaging/Agent/Store/AgentStore.hs
@@ -58,6 +58,7 @@ module Simplex.Messaging.Agent.Store.AgentStore
     getRcvQueueById,
     getSndQueueById,
     deleteConn,
+    deleteConnRecord,
     upgradeRcvConnToDuplex,
     upgradeSndConnToDuplex,
     addConnRcvQueue,
@@ -88,6 +89,12 @@ module Simplex.Messaging.Agent.Store.AgentStore
     acceptInvitation,
     unacceptInvitation,
     deleteInvitation,
+    getInvShortLink,
+    getInvShortLinkKeys,
+    deleteInvShortLink,
+    createInvShortLink,
+    setInvShortLinkSndId,
+    updateShortLinkCreds,
     -- Messages
     updateRcvIds,
     createRcvMsg,
@@ -410,6 +417,9 @@ createConnRecord db connId ConnData {userId, connAgentVersion, enableNtfs, pqSup
     |]
     (userId, connId, cMode, connAgentVersion, BI enableNtfs, pqSupport, BI True)
 
+deleteConnRecord :: DB.Connection -> ConnId -> IO ()
+deleteConnRecord db connId = DB.execute db "DELETE FROM connections WHERE conn_id = ?" (Only connId)
+
 checkConfirmedSndQueueExists_ :: DB.Connection -> NewSndQueue -> IO Bool
 checkConfirmedSndQueueExists_ db SndQueue {server, sndId} = do
   fromMaybe False
@@ -442,7 +452,7 @@ deleteConn db waitDeliveryTimeout_ connId = case waitDeliveryTimeout_ of
           (pure Nothing)
       )
   where
-    delete = DB.execute db "DELETE FROM connections WHERE conn_id = ?" (Only connId) $> Just connId
+    delete = deleteConnRecord db connId $> Just connId
     checkNoPendingDeliveries_ = do
       r :: (Maybe Int64) <-
         maybeFirstRow fromOnly $
@@ -756,6 +766,82 @@ deleteInvitation db contactConnId invId =
       Right <$> DB.execute db "DELETE FROM conn_invitations WHERE contact_conn_id = ? AND invitation_id = ?" (contactConnId, Binary invId)
     _ -> pure $ Left SEConnNotFound
 
+getInvShortLink :: DB.Connection -> SMPServer -> LinkId -> IO (Maybe InvShortLink)
+getInvShortLink db server linkId =
+  maybeFirstRow toInvShortLink $
+    DB.query
+      db
+      [sql|
+        SELECT link_key, snd_private_key, snd_id
+        FROM inv_short_links
+        WHERE host = ? AND port = ? AND link_id = ?
+      |]
+      (host server, port server, linkId)
+  where
+    toInvShortLink :: (LinkKey, C.APrivateAuthKey, Maybe SenderId) -> InvShortLink
+    toInvShortLink (linkKey, sndPrivateKey@(C.APrivateAuthKey a pk), sndId) =
+      let sndPublicKey = C.APublicAuthKey a $ C.publicKey pk
+       in InvShortLink {server, linkId, linkKey, sndPrivateKey, sndPublicKey, sndId}
+
+getInvShortLinkKeys :: DB.Connection -> SMPServer -> SenderId -> IO (Maybe (LinkId, C.AAuthKeyPair))
+getInvShortLinkKeys db srv sndId =
+  maybeFirstRow toSndKeys $
+    DB.query
+      db
+      [sql|
+        SELECT link_id, snd_private_key
+        FROM inv_short_links
+        WHERE host = ? AND port = ? AND snd_id = ?
+      |]
+      (host srv, port srv, sndId)
+  where
+    toSndKeys :: (LinkId, C.APrivateAuthKey) -> (LinkId, C.AAuthKeyPair)
+    toSndKeys (linkId, privKey@(C.APrivateAuthKey a pk)) = (linkId, (C.APublicAuthKey a $ C.publicKey pk, privKey))
+
+deleteInvShortLink :: DB.Connection -> SMPServer -> LinkId -> IO ()
+deleteInvShortLink db srv lnkId =
+  DB.execute db "DELETE FROM inv_short_links WHERE host = ? AND port = ? AND link_id = ?" (host srv, port srv, lnkId)
+
+createInvShortLink :: DB.Connection -> InvShortLink -> IO ()
+createInvShortLink db InvShortLink {server, linkId, linkKey, sndPrivateKey, sndId} = do
+  serverKeyHash_ <- createServer_ db server
+  DB.execute
+    db
+    [sql|
+      INSERT INTO inv_short_links
+        (host, port, server_key_hash, link_id, link_key, snd_private_key, snd_id)
+      VALUES (?,?,?,?,?,?,?)
+      ON CONFLICT (host, port, link_id)
+      DO UPDATE SET
+        server_key_hash = EXCLUDED.server_key_hash,
+        link_key = EXCLUDED.link_key,
+        snd_private_key = EXCLUDED.snd_private_key,
+        snd_id = EXCLUDED.snd_id
+    |]
+    (host server, port server, serverKeyHash_, linkId, linkKey, sndPrivateKey, sndId)
+
+setInvShortLinkSndId :: DB.Connection -> InvShortLink -> SenderId -> IO ()
+setInvShortLinkSndId db InvShortLink {server, linkId} sndId =
+  DB.execute
+    db
+    [sql|
+      UPDATE inv_short_links
+      SET snd_id = ?
+      WHERE host = ? AND port = ? AND link_id = ?
+    |]
+    (sndId, host server, port server, linkId)
+
+updateShortLinkCreds :: DB.Connection -> RcvQueue -> ShortLinkCreds -> IO ()
+updateShortLinkCreds db RcvQueue {server, rcvId} ShortLinkCreds {shortLinkId, shortLinkKey, linkPrivSigKey, linkEncFixedData} =
+  DB.execute
+    db
+    [sql|
+      UPDATE rcv_queues
+      SET link_id = ?, link_key = ?, link_priv_sig_key = ?, link_enc_fixed_data = ?
+      WHERE host = ? AND port = ? AND rcv_id = ?
+    |]
+    (shortLinkId, shortLinkKey, linkPrivSigKey, linkEncFixedData, host server, port server, rcvId)
+
 updateRcvIds :: DB.Connection -> ConnId -> IO (InternalId, InternalRcvId, PrevExternalSndId, PrevRcvMsgHash)
 updateRcvIds db connId = do
   (lastInternalId, lastInternalRcvId, lastExternalSndId, lastRcvHash) <- retrieveLastIdsAndHashRcv_ db connId
@@ -1884,9 +1970,15 @@ insertRcvQueue_ db connId' rq@RcvQueue {..} serverKeyHash_ = do
     db
     [sql|
       INSERT INTO rcv_queues
-        (host, port, rcv_id, conn_id, rcv_private_key, rcv_dh_secret, e2e_priv_key, e2e_dh_secret, snd_id, snd_secure, status, rcv_queue_id, rcv_primary, replace_rcv_queue_id, smp_client_version, server_key_hash) VALUES (?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?);
+        ( host, port, rcv_id, conn_id, rcv_private_key, rcv_dh_secret, e2e_priv_key, e2e_dh_secret,
+          snd_id, queue_mode, status, rcv_queue_id, rcv_primary, replace_rcv_queue_id, smp_client_version, server_key_hash,
+          link_id, link_key, link_priv_sig_key, link_enc_fixed_data
+        ) VALUES (?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?);
     |]
-    ((host server, port server, rcvId, connId', rcvPrivateKey, rcvDhSecret, e2ePrivKey, e2eDhSecret) :. (sndId, BI sndSecure, status, qId, BI primary, dbReplaceQueueId, smpClientVersion, serverKeyHash_))
+    ( (host server, port server, rcvId, connId', rcvPrivateKey, rcvDhSecret, e2ePrivKey, e2eDhSecret)
+        :. (sndId, queueMode, status, qId, BI primary, dbReplaceQueueId, smpClientVersion, serverKeyHash_)
+        :. (shortLinkId <$> shortLink, shortLinkKey <$> shortLink, linkPrivSigKey <$> shortLink, linkEncFixedData <$> shortLink)
+    )
   pure (rq :: NewRcvQueue) {connId = connId', dbQueueId = qId}
 
 -- * createSndConn helpers
@@ -1901,14 +1993,14 @@ insertSndQueue_ db connId' sq@SndQueue {..} serverKeyHash_ = do
     db
     [sql|
       INSERT INTO snd_queues
-        (host, port, snd_id, snd_secure, conn_id, snd_public_key, snd_private_key, e2e_pub_key, e2e_dh_secret,
+        (host, port, snd_id, queue_mode, conn_id, snd_public_key, snd_private_key, e2e_pub_key, e2e_dh_secret,
          status, snd_queue_id, snd_primary, replace_snd_queue_id, smp_client_version, server_key_hash)
       VALUES (?,?,?,?,?,?,?,?,?,?,?,?,?,?,?)
       ON CONFLICT (host, port, snd_id) DO UPDATE SET
         host=EXCLUDED.host,
         port=EXCLUDED.port,
         snd_id=EXCLUDED.snd_id,
-        snd_secure=EXCLUDED.snd_secure,
+        queue_mode=EXCLUDED.queue_mode,
         conn_id=EXCLUDED.conn_id,
         snd_public_key=EXCLUDED.snd_public_key,
         snd_private_key=EXCLUDED.snd_private_key,
@@ -1921,7 +2013,7 @@ insertSndQueue_ db connId' sq@SndQueue {..} serverKeyHash_ = do
         smp_client_version=EXCLUDED.smp_client_version,
         server_key_hash=EXCLUDED.server_key_hash
     |]
-    ((host server, port server, sndId, BI sndSecure, connId', sndPublicKey, sndPrivateKey, e2ePubKey, e2eDhSecret) 
+    ((host server, port server, sndId, queueMode, connId', sndPublicKey, sndPrivateKey, e2ePubKey, e2eDhSecret) 
     :. (status, qId, BI primary, dbReplaceQueueId, smpClientVersion, serverKeyHash_))
   pure (sq :: NewSndQueue) {connId = connId', dbQueueId = qId}
 
@@ -2052,26 +2144,36 @@ rcvQueueQuery :: Query
 rcvQueueQuery =
   [sql|
     SELECT c.user_id, COALESCE(q.server_key_hash, s.key_hash), q.conn_id, q.host, q.port, q.rcv_id, q.rcv_private_key, q.rcv_dh_secret,
-      q.e2e_priv_key, q.e2e_dh_secret, q.snd_id, q.snd_secure, q.status,
+      q.e2e_priv_key, q.e2e_dh_secret, q.snd_id, q.queue_mode, q.status,
       q.rcv_queue_id, q.rcv_primary, q.replace_rcv_queue_id, q.switch_status, q.smp_client_version, q.delete_errors,
-      q.ntf_public_key, q.ntf_private_key, q.ntf_id, q.rcv_ntf_dh_secret
+      q.ntf_public_key, q.ntf_private_key, q.ntf_id, q.rcv_ntf_dh_secret,
+      q.link_id, q.link_key, q.link_priv_sig_key, q.link_enc_fixed_data
     FROM rcv_queues q
     JOIN servers s ON q.host = s.host AND q.port = s.port
     JOIN connections c ON q.conn_id = c.conn_id
   |]
 
 toRcvQueue ::
-  (UserId, C.KeyHash, ConnId, NonEmpty TransportHost, ServiceName, SMP.RecipientId, SMP.RcvPrivateAuthKey, SMP.RcvDhSecret, C.PrivateKeyX25519, Maybe C.DhSecretX25519, SMP.SenderId, BoolInt)
+  (UserId, C.KeyHash, ConnId, NonEmpty TransportHost, ServiceName, SMP.RecipientId, SMP.RcvPrivateAuthKey, SMP.RcvDhSecret, C.PrivateKeyX25519, Maybe C.DhSecretX25519, SMP.SenderId, Maybe QueueMode)
     :. (QueueStatus, DBQueueId 'QSStored, BoolInt, Maybe Int64, Maybe RcvSwitchStatus, Maybe VersionSMPC, Int)
-    :. (Maybe SMP.NtfPublicAuthKey, Maybe SMP.NtfPrivateAuthKey, Maybe SMP.NotifierId, Maybe RcvNtfDhSecret) ->
+    :. (Maybe SMP.NtfPublicAuthKey, Maybe SMP.NtfPrivateAuthKey, Maybe SMP.NotifierId, Maybe RcvNtfDhSecret)
+    :. (Maybe SMP.LinkId, Maybe LinkKey, Maybe C.PrivateKeyEd25519, Maybe EncDataBytes) ->
   RcvQueue
-toRcvQueue ((userId, keyHash, connId, host, port, rcvId, rcvPrivateKey, rcvDhSecret, e2ePrivKey, e2eDhSecret, sndId, BI sndSecure) :. (status, dbQueueId, BI primary, dbReplaceQueueId, rcvSwchStatus, smpClientVersion_, deleteErrors) :. (ntfPublicKey_, ntfPrivateKey_, notifierId_, rcvNtfDhSecret_)) =
+toRcvQueue
+  ( (userId, keyHash, connId, host, port, rcvId, rcvPrivateKey, rcvDhSecret, e2ePrivKey, e2eDhSecret, sndId, queueMode)
+      :. (status, dbQueueId, BI primary, dbReplaceQueueId, rcvSwchStatus, smpClientVersion_, deleteErrors)
+      :. (ntfPublicKey_, ntfPrivateKey_, notifierId_, rcvNtfDhSecret_)
+      :. (shortLinkId_, shortLinkKey_, linkPrivSigKey_, linkEncFixedData_)
+  ) =
   let server = SMPServer host port keyHash
       smpClientVersion = fromMaybe initialSMPClientVersion smpClientVersion_
       clientNtfCreds = case (ntfPublicKey_, ntfPrivateKey_, notifierId_, rcvNtfDhSecret_) of
-        (Just ntfPublicKey, Just ntfPrivateKey, Just notifierId, Just rcvNtfDhSecret) -> Just $ ClientNtfCreds {ntfPublicKey, ntfPrivateKey, notifierId, rcvNtfDhSecret}
+        (Just ntfPublicKey, Just ntfPrivateKey, Just notifierId, Just rcvNtfDhSecret) -> Just ClientNtfCreds {ntfPublicKey, ntfPrivateKey, notifierId, rcvNtfDhSecret}
+        _ -> Nothing
+      shortLink = case (shortLinkId_, shortLinkKey_, linkPrivSigKey_, linkEncFixedData_) of
+        (Just shortLinkId, Just shortLinkKey, Just linkPrivSigKey, Just linkEncFixedData) -> Just ShortLinkCreds {shortLinkId, shortLinkKey, linkPrivSigKey, linkEncFixedData}
         _ -> Nothing
-   in RcvQueue {userId, connId, server, rcvId, rcvPrivateKey, rcvDhSecret, e2ePrivKey, e2eDhSecret, sndId, sndSecure, status, dbQueueId, primary, dbReplaceQueueId, rcvSwchStatus, smpClientVersion, clientNtfCreds, deleteErrors}
+   in RcvQueue {userId, connId, server, rcvId, rcvPrivateKey, rcvDhSecret, e2ePrivKey, e2eDhSecret, sndId, queueMode, shortLink, status, dbQueueId, primary, dbReplaceQueueId, rcvSwchStatus, smpClientVersion, clientNtfCreds, deleteErrors}
 
 getRcvQueueById :: DB.Connection -> ConnId -> Int64 -> IO (Either StoreError RcvQueue)
 getRcvQueueById db connId dbRcvId =
@@ -2092,7 +2194,7 @@ sndQueueQuery :: Query
 sndQueueQuery =
   [sql|
     SELECT
-      c.user_id, COALESCE(q.server_key_hash, s.key_hash), q.conn_id, q.host, q.port, q.snd_id, q.snd_secure,
+      c.user_id, COALESCE(q.server_key_hash, s.key_hash), q.conn_id, q.host, q.port, q.snd_id, q.queue_mode,
       q.snd_public_key, q.snd_private_key, q.e2e_pub_key, q.e2e_dh_secret, q.status,
       q.snd_queue_id, q.snd_primary, q.replace_snd_queue_id, q.switch_status, q.smp_client_version
     FROM snd_queues q
@@ -2101,18 +2203,18 @@ sndQueueQuery =
   |]
 
 toSndQueue ::
-  (UserId, C.KeyHash, ConnId, NonEmpty TransportHost, ServiceName, SenderId, BoolInt)
+  (UserId, C.KeyHash, ConnId, NonEmpty TransportHost, ServiceName, SenderId, Maybe QueueMode)
     :. (Maybe SndPublicAuthKey, SndPrivateAuthKey, Maybe C.PublicKeyX25519, C.DhSecretX25519, QueueStatus)
     :. (DBQueueId 'QSStored, BoolInt, Maybe Int64, Maybe SndSwitchStatus, VersionSMPC) ->
   SndQueue
 toSndQueue
-  ( (userId, keyHash, connId, host, port, sndId, BI sndSecure)
+  ( (userId, keyHash, connId, host, port, sndId, queueMode)
       :. (sndPubKey, sndPrivateKey@(C.APrivateAuthKey a pk), e2ePubKey, e2eDhSecret, status)
       :. (dbQueueId, BI primary, dbReplaceQueueId, sndSwchStatus, smpClientVersion)
     ) =
     let server = SMPServer host port keyHash
         sndPublicKey = fromMaybe (C.APublicAuthKey a (C.publicKey pk)) sndPubKey
-     in SndQueue {userId, connId, server, sndId, sndSecure, sndPublicKey, sndPrivateKey, e2ePubKey, e2eDhSecret, status, dbQueueId, primary, dbReplaceQueueId, sndSwchStatus, smpClientVersion}
+     in SndQueue {userId, connId, server, sndId, queueMode, sndPublicKey, sndPrivateKey, e2ePubKey, e2eDhSecret, status, dbQueueId, primary, dbReplaceQueueId, sndSwchStatus, smpClientVersion}
 
 getSndQueueById :: DB.Connection -> ConnId -> Int64 -> IO (Either StoreError SndQueue)
 getSndQueueById db connId dbSndId =
diff --git a/src/Simplex/Messaging/Agent/Store/Postgres/Migrations/App.hs b/src/Simplex/Messaging/Agent/Store/Postgres/Migrations/App.hs
index e47fe432ac..e6e6efaf8c 100644
--- a/src/Simplex/Messaging/Agent/Store/Postgres/Migrations/App.hs
+++ b/src/Simplex/Messaging/Agent/Store/Postgres/Migrations/App.hs
@@ -6,12 +6,14 @@ import Data.List (sortOn)
 import Data.Text (Text)
 import Simplex.Messaging.Agent.Store.Postgres.Migrations.M20241210_initial
 import Simplex.Messaging.Agent.Store.Postgres.Migrations.M20250203_msg_bodies
+import Simplex.Messaging.Agent.Store.Postgres.Migrations.M20250322_short_links
 import Simplex.Messaging.Agent.Store.Shared (Migration (..))
 
 schemaMigrations :: [(String, Text, Maybe Text)]
 schemaMigrations =
   [ ("20241210_initial", m20241210_initial, Nothing),
-    ("20250203_msg_bodies", m20250203_msg_bodies, Just down_m20250203_msg_bodies)
+    ("20250203_msg_bodies", m20250203_msg_bodies, Just down_m20250203_msg_bodies),
+    ("20250322_short_links", m20250322_short_links, Just down_m20250322_short_links)
   ]
 
 -- | The list of migrations in ascending order by date
diff --git a/src/Simplex/Messaging/Agent/Store/Postgres/Migrations/M20250322_short_links.hs b/src/Simplex/Messaging/Agent/Store/Postgres/Migrations/M20250322_short_links.hs
new file mode 100644
index 0000000000..be627ea0ad
--- /dev/null
+++ b/src/Simplex/Messaging/Agent/Store/Postgres/Migrations/M20250322_short_links.hs
@@ -0,0 +1,63 @@
+{-# LANGUAGE QuasiQuotes #-}
+
+module Simplex.Messaging.Agent.Store.Postgres.Migrations.M20250322_short_links where
+
+import Data.Text (Text)
+import qualified Data.Text as T
+import Text.RawString.QQ (r)
+
+m20250322_short_links :: Text
+m20250322_short_links =
+  T.pack    
+    [r|
+ALTER TABLE rcv_queues ADD COLUMN link_id BYTEA;
+ALTER TABLE rcv_queues ADD COLUMN link_key BYTEA;
+ALTER TABLE rcv_queues ADD COLUMN link_priv_sig_key BYTEA;
+ALTER TABLE rcv_queues ADD COLUMN link_enc_fixed_data BYTEA;
+
+CREATE UNIQUE INDEX idx_rcv_queues_link_id ON rcv_queues(host, port, link_id);
+
+ALTER TABLE rcv_queues ADD COLUMN queue_mode TEXT;
+UPDATE rcv_queues SET queue_mode = 'M' WHERE snd_secure = 1;
+ALTER TABLE rcv_queues DROP COLUMN snd_secure;
+
+ALTER TABLE snd_queues ADD COLUMN queue_mode TEXT;
+UPDATE snd_queues SET queue_mode = 'M' WHERE snd_secure = 1;
+ALTER TABLE snd_queues DROP COLUMN snd_secure;
+
+CREATE TABLE inv_short_links(
+  inv_short_link_id BIGINT PRIMARY KEY GENERATED ALWAYS AS IDENTITY,
+  host TEXT NOT NULL,
+  port TEXT NOT NULL,
+  server_key_hash BYTEA,
+  link_id BYTEA NOT NULL,
+  link_key BYTEA NOT NULL,
+  snd_private_key BYTEA NOT NULL,
+  snd_id BYTEA,
+  FOREIGN KEY(host, port) REFERENCES servers ON DELETE RESTRICT ON UPDATE CASCADE
+);
+
+CREATE UNIQUE INDEX idx_inv_short_links_link_id ON inv_short_links(host, port, link_id);
+|]
+
+down_m20250322_short_links :: Text
+down_m20250322_short_links =
+  T.pack
+    [r|
+DROP INDEX idx_rcv_queues_link_id;
+ALTER TABLE rcv_queues DROP COLUMN link_id;
+ALTER TABLE rcv_queues DROP COLUMN link_key;
+ALTER TABLE rcv_queues DROP COLUMN link_priv_sig_key;
+ALTER TABLE rcv_queues DROP COLUMN link_enc_fixed_data;
+
+DROP INDEX idx_inv_short_links_link_id;
+DROP TABLE inv_short_links;
+
+ALTER TABLE rcv_queues ADD COLUMN snd_secure INTEGER NOT NULL DEFAULT 0;
+UPDATE rcv_queues SET snd_secure = 1 WHERE queue_mode = 'M';
+ALTER TABLE rcv_queues DROP COLUMN queue_mode;
+
+ALTER TABLE snd_queues ADD COLUMN snd_secure INTEGER NOT NULL DEFAULT 0;
+UPDATE snd_queues SET snd_secure = 1 WHERE queue_mode = 'M';
+ALTER TABLE snd_queues DROP COLUMN queue_mode;
+|]
diff --git a/src/Simplex/Messaging/Agent/Store/SQLite/Migrations/App.hs b/src/Simplex/Messaging/Agent/Store/SQLite/Migrations/App.hs
index 8c885a9e59..eea7db3ca4 100644
--- a/src/Simplex/Messaging/Agent/Store/SQLite/Migrations/App.hs
+++ b/src/Simplex/Messaging/Agent/Store/SQLite/Migrations/App.hs
@@ -42,6 +42,7 @@ import Simplex.Messaging.Agent.Store.SQLite.Migrations.M20240930_ntf_tokens_to_d
 import Simplex.Messaging.Agent.Store.SQLite.Migrations.M20241007_rcv_queues_last_broker_ts
 import Simplex.Messaging.Agent.Store.SQLite.Migrations.M20241224_ratchet_e2e_snd_params
 import Simplex.Messaging.Agent.Store.SQLite.Migrations.M20250203_msg_bodies
+import Simplex.Messaging.Agent.Store.SQLite.Migrations.M20250322_short_links
 import Simplex.Messaging.Agent.Store.Shared (Migration (..))
 
 schemaMigrations :: [(String, Query, Maybe Query)]
@@ -83,7 +84,8 @@ schemaMigrations =
     ("m20240930_ntf_tokens_to_delete", m20240930_ntf_tokens_to_delete, Just down_m20240930_ntf_tokens_to_delete),
     ("m20241007_rcv_queues_last_broker_ts", m20241007_rcv_queues_last_broker_ts, Just down_m20241007_rcv_queues_last_broker_ts),
     ("m20241224_ratchet_e2e_snd_params", m20241224_ratchet_e2e_snd_params, Just down_m20241224_ratchet_e2e_snd_params),
-    ("m20250203_msg_bodies", m20250203_msg_bodies, Just down_m20250203_msg_bodies)
+    ("m20250203_msg_bodies", m20250203_msg_bodies, Just down_m20250203_msg_bodies),
+    ("m20250322_short_links", m20250322_short_links, Just down_m20250322_short_links)
   ]
 
 -- | The list of migrations in ascending order by date
diff --git a/src/Simplex/Messaging/Agent/Store/SQLite/Migrations/M20250322_short_links.hs b/src/Simplex/Messaging/Agent/Store/SQLite/Migrations/M20250322_short_links.hs
new file mode 100644
index 0000000000..c6cbd423b0
--- /dev/null
+++ b/src/Simplex/Messaging/Agent/Store/SQLite/Migrations/M20250322_short_links.hs
@@ -0,0 +1,60 @@
+{-# LANGUAGE QuasiQuotes #-}
+
+module Simplex.Messaging.Agent.Store.SQLite.Migrations.M20250322_short_links where
+
+import Database.SQLite.Simple (Query)
+import Database.SQLite.Simple.QQ (sql)
+
+m20250322_short_links :: Query
+m20250322_short_links =
+  [sql|
+ALTER TABLE rcv_queues ADD COLUMN link_id BLOB;
+ALTER TABLE rcv_queues ADD COLUMN link_key BLOB;
+ALTER TABLE rcv_queues ADD COLUMN link_priv_sig_key BLOB;
+ALTER TABLE rcv_queues ADD COLUMN link_enc_fixed_data BLOB;
+
+CREATE UNIQUE INDEX idx_rcv_queues_link_id ON rcv_queues(host, port, link_id);
+
+ALTER TABLE rcv_queues ADD COLUMN queue_mode TEXT;
+UPDATE rcv_queues SET queue_mode = 'M' WHERE snd_secure = 1;
+ALTER TABLE rcv_queues DROP COLUMN snd_secure;
+
+ALTER TABLE snd_queues ADD COLUMN queue_mode TEXT;
+UPDATE snd_queues SET queue_mode = 'M' WHERE snd_secure = 1;
+ALTER TABLE snd_queues DROP COLUMN snd_secure;
+
+CREATE TABLE inv_short_links(
+  inv_short_link_id INTEGER PRIMARY KEY AUTOINCREMENT,
+  host TEXT NOT NULL,
+  port TEXT NOT NULL,
+  server_key_hash BLOB,
+  link_id BLOB NOT NULL,
+  link_key BLOB NOT NULL,
+  snd_private_key BLOB NOT NULL,
+  snd_id BLOB,
+  FOREIGN KEY(host, port) REFERENCES servers ON DELETE RESTRICT ON UPDATE CASCADE
+);
+
+CREATE UNIQUE INDEX idx_inv_short_links_link_id ON inv_short_links(host, port, link_id);
+  |]
+
+down_m20250322_short_links :: Query
+down_m20250322_short_links =
+  [sql|
+DROP INDEX idx_rcv_queues_link_id;
+ALTER TABLE rcv_queues DROP COLUMN link_id;
+ALTER TABLE rcv_queues DROP COLUMN link_key;
+ALTER TABLE rcv_queues DROP COLUMN link_priv_sig_key;
+ALTER TABLE rcv_queues DROP COLUMN link_enc_fixed_data;
+
+DROP INDEX idx_inv_short_links_link_id;
+DROP TABLE inv_short_links;
+
+ALTER TABLE rcv_queues ADD COLUMN snd_secure INTEGER NOT NULL DEFAULT 0;
+UPDATE rcv_queues SET snd_secure = 1 WHERE queue_mode = 'M';
+ALTER TABLE rcv_queues DROP COLUMN queue_mode;
+
+ALTER TABLE snd_queues ADD COLUMN snd_secure INTEGER NOT NULL DEFAULT 0;
+UPDATE snd_queues SET snd_secure = 1 WHERE queue_mode = 'M';
+ALTER TABLE snd_queues DROP COLUMN queue_mode;
+  |]
diff --git a/src/Simplex/Messaging/Agent/Store/SQLite/Migrations/agent_schema.sql b/src/Simplex/Messaging/Agent/Store/SQLite/Migrations/agent_schema.sql
index 3f9a468e17..fde671d7ae 100644
--- a/src/Simplex/Messaging/Agent/Store/SQLite/Migrations/agent_schema.sql
+++ b/src/Simplex/Messaging/Agent/Store/SQLite/Migrations/agent_schema.sql
@@ -55,8 +55,12 @@ CREATE TABLE rcv_queues(
   server_key_hash BLOB,
   switch_status TEXT,
   deleted INTEGER NOT NULL DEFAULT 0,
-  snd_secure INTEGER NOT NULL DEFAULT 0,
   last_broker_ts TEXT,
+  link_id BLOB,
+  link_key BLOB,
+  link_priv_sig_key BLOB,
+  link_enc_fixed_data BLOB,
+  queue_mode TEXT,
   PRIMARY KEY(host, port, rcv_id),
   FOREIGN KEY(host, port) REFERENCES servers
   ON DELETE RESTRICT ON UPDATE CASCADE,
@@ -79,7 +83,7 @@ CREATE TABLE snd_queues(
   replace_snd_queue_id INTEGER NULL,
   server_key_hash BLOB,
   switch_status TEXT,
-  snd_secure INTEGER NOT NULL DEFAULT 0,
+  queue_mode TEXT,
   PRIMARY KEY(host, port, snd_id),
   FOREIGN KEY(host, port) REFERENCES servers
   ON DELETE RESTRICT ON UPDATE CASCADE
@@ -422,6 +426,17 @@ CREATE TABLE snd_message_bodies(
   snd_message_body_id INTEGER PRIMARY KEY,
   agent_msg BLOB NOT NULL DEFAULT x''
 );
+CREATE TABLE inv_short_links(
+  inv_short_link_id INTEGER PRIMARY KEY AUTOINCREMENT,
+  host TEXT NOT NULL,
+  port TEXT NOT NULL,
+  server_key_hash BLOB,
+  link_id BLOB NOT NULL,
+  link_key BLOB NOT NULL,
+  snd_private_key BLOB NOT NULL,
+  snd_id BLOB,
+  FOREIGN KEY(host, port) REFERENCES servers ON DELETE RESTRICT ON UPDATE CASCADE
+);
 CREATE UNIQUE INDEX idx_rcv_queues_ntf ON rcv_queues(host, port, ntf_id);
 CREATE UNIQUE INDEX idx_rcv_queue_id ON rcv_queues(conn_id, rcv_queue_id);
 CREATE UNIQUE INDEX idx_snd_queue_id ON snd_queues(conn_id, snd_queue_id);
@@ -551,3 +566,9 @@ CREATE INDEX idx_rcv_files_redirect_id on rcv_files(redirect_id);
 CREATE INDEX idx_snd_messages_snd_message_body_id ON snd_messages(
   snd_message_body_id
 );
+CREATE UNIQUE INDEX idx_rcv_queues_link_id ON rcv_queues(host, port, link_id);
+CREATE UNIQUE INDEX idx_inv_short_links_link_id ON inv_short_links(
+  host,
+  port,
+  link_id
+);
diff --git a/src/Simplex/Messaging/Client.hs b/src/Simplex/Messaging/Client.hs
index df12e5fcee..7c18a0aa15 100644
--- a/src/Simplex/Messaging/Client.hs
+++ b/src/Simplex/Messaging/Client.hs
@@ -49,6 +49,12 @@ module Simplex.Messaging.Client
     secureSMPQueue,
     secureSndSMPQueue,
     proxySecureSndSMPQueue,
+    addSMPQueueLink,
+    deleteSMPQueueLink,
+    secureGetSMPQueueLink,
+    proxySecureGetSMPQueueLink,
+    getSMPQueueLink,
+    proxyGetSMPQueueLink,
     enableSMPQueueNotifications,
     disableSMPQueueNotifications,
     enableSMPQueuesNtfs,
@@ -101,6 +107,7 @@ module Simplex.Messaging.Client
     TBQueueInfo (..),
     getTBQueueInfo,
     getProtocolClientQueuesInfo,
+    nonBlockingWriteTBQueue,
   )
 where
 
@@ -706,14 +713,17 @@ smpProxyError = \case
 -- https://github.com/simplex-chat/simplexmq/blob/master/protocol/simplex-messaging.md#create-queue-command
 createSMPQueue ::
   SMPClient ->
+  Maybe C.CbNonce -> -- used as correlation ID to allow deriving SenderId from it for short links
   C.AAuthKeyPair -> -- SMP v6 - signature key pair, SMP v7 - DH key pair
   RcvPublicDhKey ->
   Maybe BasicAuth ->
   SubscriptionMode ->
-  Bool ->
+  QueueReqData ->
+  -- TODO [notifications]
+  -- Maybe NewNtfCreds ->
   ExceptT SMPClientError IO QueueIdsKeys
-createSMPQueue c (rKey, rpKey) dhKey auth subMode sndSecure =
-  sendSMPCommand c (Just rpKey) NoEntity (NEW rKey dhKey auth subMode sndSecure) >>= \case
+createSMPQueue c nonce_ (rKey, rpKey) dhKey auth subMode qrd =
+  sendProtocolCommand_ c nonce_ Nothing (Just rpKey) NoEntity (Cmd SRecipient $ NEW $ NewQueueReq rKey dhKey auth subMode (Just qrd)) >>= \case
     IDS qik -> pure qik
     r -> throwE $ unexpectedResponse r
 
@@ -799,9 +809,47 @@ secureSndSMPQueue c spKey sId senderKey = okSMPCommand (SKEY senderKey) c spKey
 {-# INLINE secureSndSMPQueue #-}
 
 proxySecureSndSMPQueue :: SMPClient -> ProxiedRelay -> SndPrivateAuthKey -> SenderId -> SndPublicAuthKey -> ExceptT SMPClientError IO (Either ProxyClientError ())
-proxySecureSndSMPQueue c proxiedRelay spKey sId senderKey = proxySMPCommand c proxiedRelay (Just spKey) sId (SKEY senderKey)
+proxySecureSndSMPQueue c proxiedRelay spKey sId senderKey = proxyOKSMPCommand c proxiedRelay (Just spKey) sId (SKEY senderKey)
 {-# INLINE proxySecureSndSMPQueue #-}
 
+-- | Add or update date for queue link
+addSMPQueueLink :: SMPClient -> RcvPrivateAuthKey -> RecipientId -> LinkId -> QueueLinkData -> ExceptT SMPClientError IO ()
+addSMPQueueLink c rpKey rId lnkId d = okSMPCommand (LSET lnkId d) c rpKey rId
+{-# INLINE addSMPQueueLink #-}
+
+-- | Delete queue link
+deleteSMPQueueLink :: SMPClient -> RcvPrivateAuthKey -> RecipientId -> ExceptT SMPClientError IO ()
+deleteSMPQueueLink = okSMPCommand LDEL
+{-# INLINE deleteSMPQueueLink #-}
+
+-- | Get 1-time inviation SMP queue link data and secure the queue via queue link ID.
+secureGetSMPQueueLink :: SMPClient -> SndPrivateAuthKey -> LinkId -> SndPublicAuthKey -> ExceptT SMPClientError IO (SenderId, QueueLinkData)
+secureGetSMPQueueLink c spKey lnkId senderKey =
+  sendSMPCommand c (Just spKey) lnkId (LKEY senderKey) >>= \case
+    LNK sId d -> pure (sId, d)
+    r -> throwE $ unexpectedResponse r
+
+proxySecureGetSMPQueueLink :: SMPClient -> ProxiedRelay -> SndPrivateAuthKey -> LinkId -> SndPublicAuthKey -> ExceptT SMPClientError IO (Either ProxyClientError (SenderId, QueueLinkData))
+proxySecureGetSMPQueueLink c proxiedRelay spKey lnkId senderKey =
+  proxySMPCommand  c proxiedRelay (Just spKey) lnkId (LKEY senderKey) >>= \case
+    Right (LNK sId d) -> pure $ Right (sId, d)
+    Right r -> throwE $ unexpectedResponse r
+    Left e -> pure $ Left e
+
+-- | Get contact address SMP queue link data.
+getSMPQueueLink :: SMPClient -> LinkId -> ExceptT SMPClientError IO (SenderId, QueueLinkData)
+getSMPQueueLink c lnkId =
+  sendSMPCommand c Nothing lnkId LGET >>= \case
+    LNK sId d -> pure (sId, d)
+    r -> throwE $ unexpectedResponse r
+
+proxyGetSMPQueueLink :: SMPClient -> ProxiedRelay -> LinkId -> ExceptT SMPClientError IO (Either ProxyClientError (SenderId, QueueLinkData))
+proxyGetSMPQueueLink c proxiedRelay lnkId =
+  proxySMPCommand  c proxiedRelay Nothing lnkId LGET >>= \case
+    Right (LNK sId d) -> pure $ Right (sId, d)
+    Right r -> throwE $ unexpectedResponse r
+    Left e -> pure $ Left e
+
 -- | Enable notifications for the queue for push notifications server.
 --
 -- https://github.com/simplex-chat/simplexmq/blob/master/protocol/simplex-messaging.md#enable-notifications-command
@@ -843,7 +891,7 @@ sendSMPMessage c spKey sId flags msg =
     r -> throwE $ unexpectedResponse r
 
 proxySMPMessage :: SMPClient -> ProxiedRelay -> Maybe SndPrivateAuthKey -> SenderId -> MsgFlags -> MsgBody -> ExceptT SMPClientError IO (Either ProxyClientError ())
-proxySMPMessage c proxiedRelay spKey sId flags msg = proxySMPCommand c proxiedRelay spKey sId (SEND flags msg)
+proxySMPMessage c proxiedRelay spKey sId flags msg = proxyOKSMPCommand c proxiedRelay spKey sId (SEND flags msg)
 
 -- | Acknowledge message delivery (server deletes the message).
 --
@@ -955,15 +1003,24 @@ instance StrEncoding ProxyClientError where
 -- - other errors from the client running on proxy and connected to relay in PREProxiedRelayError
 
 -- This function proxies Sender commands that return OK or ERR
+proxyOKSMPCommand :: SMPClient -> ProxiedRelay -> Maybe SndPrivateAuthKey -> SenderId -> Command 'Sender -> ExceptT SMPClientError IO (Either ProxyClientError ())
+proxyOKSMPCommand c proxiedRelay spKey sId command =
+  proxySMPCommand  c proxiedRelay spKey sId command >>= \case
+    Right OK -> pure $ Right ()
+    Right r -> throwE $ unexpectedResponse r
+    Left e -> pure $ Left e
+
 proxySMPCommand ::
+  forall p.
+  PartyI p =>
   SMPClient ->
   -- proxy session from PKEY
   ProxiedRelay ->
   -- message to deliver
   Maybe SndPrivateAuthKey ->
   SenderId ->
-  Command 'Sender ->
-  ExceptT SMPClientError IO (Either ProxyClientError ())
+  Command p ->
+  ExceptT SMPClientError IO (Either ProxyClientError BrokerMsg)
 proxySMPCommand c@ProtocolClient {thParams = proxyThParams, client_ = PClient {clientCorrId = g, tcpTimeout}} (ProxiedRelay sessionId v _ serverKey) spKey sId command = do
   -- prepare params
   let serverThAuth = (\ta -> ta {serverPeerPubKey = serverKey}) <$> thAuth proxyThParams
@@ -972,7 +1029,7 @@ proxySMPCommand c@ProtocolClient {thParams = proxyThParams, client_ = PClient {c
   let cmdSecret = C.dh' serverKey cmdPrivKey
   nonce@(C.CbNonce corrId) <- liftIO . atomically $ C.randomCbNonce g
   -- encode
-  let TransmissionForAuth {tForAuth, tToSend} = encodeTransmissionForAuth serverThParams (CorrId corrId, sId, Cmd SSender command)
+  let TransmissionForAuth {tForAuth, tToSend} = encodeTransmissionForAuth serverThParams (CorrId corrId, sId, Cmd (sParty @p) command)
   auth <- liftEitherWith PCETransportError $ authTransmission serverThAuth spKey nonce tForAuth
   b <- case batchTransmissions (batch serverThParams) (blockSize serverThParams) [Right (auth, tToSend)] of
     [] -> throwE $ PCETransportError TELargeMsg
@@ -990,9 +1047,8 @@ proxySMPCommand c@ProtocolClient {thParams = proxyThParams, client_ = PClient {c
         case tParse serverThParams t' of
           t'' :| [] -> case tDecodeParseValidate serverThParams t'' of
             (_auth, _signed, (_c, _e, cmd)) -> case cmd of
-              Right OK -> pure $ Right ()
               Right (ERR e) -> throwE $ PCEProtocolError e -- this is the error from the destination relay
-              Right r' -> throwE $ unexpectedResponse r'
+              Right r' -> pure $ Right r'
               Left e -> throwE $ PCEResponseError e
           _ -> throwE $ PCETransportError TEBadBlock
       ERR e -> pure . Left $ ProxyProtocolError e -- this will not happen, this error is returned via Left
@@ -1101,6 +1157,8 @@ sendProtocolCommand c = sendProtocolCommand_ c Nothing Nothing
 -- This is to reflect the fact that we send subscriptions only as batches, and also because we do not track a separate timeout for the whole batch, so it is not obvious when should we expire it.
 -- We could expire a batch of deletes, for example, either when the first response expires or when the last one does.
 -- But a better solution is to process delayed delete responses.
+--
+-- Please note: if nonce is passed it is also used as a correlation ID
 sendProtocolCommand_ :: forall v err msg. Protocol v err msg => ProtocolClient v err msg -> Maybe C.CbNonce -> Maybe Int -> Maybe C.APrivateAuthKey -> EntityId -> ProtoCommand msg -> ExceptT (ProtocolClientError err) IO msg
 sendProtocolCommand_ c@ProtocolClient {client_ = PClient {sndQ}, thParams = THandleParams {batch, blockSize}} nonce_ tOut pKey entId cmd =
   ExceptT $ uncurry sendRecv =<< mkTransmission_ c nonce_ (pKey, entId, cmd)
diff --git a/src/Simplex/Messaging/Crypto.hs b/src/Simplex/Messaging/Crypto.hs
index b4af694507..e3326b98a9 100644
--- a/src/Simplex/Messaging/Crypto.hs
+++ b/src/Simplex/Messaging/Crypto.hs
@@ -142,6 +142,8 @@ module Simplex.Messaging.Crypto
     cbDecryptNoPad,
     sbDecrypt_,
     sbEncrypt_,
+    sbEncryptNoPad,
+    sbDecryptNoPad,
     cbNonce,
     randomCbNonce,
     reverseNonce,
@@ -160,6 +162,7 @@ module Simplex.Messaging.Crypto
     SbKeyNonce,
     sbcInit,
     sbcHkdf,
+    hkdf,
 
     -- * pseudo-random bytes
     randomBytes,
@@ -167,6 +170,8 @@ module Simplex.Messaging.Crypto
     -- * digests
     sha256Hash,
     sha512Hash,
+    sha3_256,
+    sha3_384,
 
     -- * Message padding / un-padding
     canPad,
@@ -207,7 +212,7 @@ import Crypto.Cipher.AES (AES256)
 import qualified Crypto.Cipher.Types as AES
 import qualified Crypto.Cipher.XSalsa as XSalsa
 import qualified Crypto.Error as CE
-import Crypto.Hash (Digest, SHA256 (..), SHA512 (..), hash, hashDigestSize)
+import Crypto.Hash (Digest, SHA3_256, SHA3_384, SHA256 (..), SHA512 (..), hash, hashDigestSize)
 import qualified Crypto.KDF.HKDF as H
 import qualified Crypto.MAC.Poly1305 as Poly1305
 import qualified Crypto.PubKey.Curve25519 as X25519
@@ -786,10 +791,19 @@ class CryptoSignature s where
 
 instance CryptoSignature (Signature s) => StrEncoding (Signature s) where
   strEncode = serializeSignature
+  {-# INLINE strEncode #-}
   strDecode = decodeSignature
+  {-# INLINE strDecode #-}
+
+instance CryptoSignature (Signature s) => Encoding (Signature s) where
+  smpEncode = smpEncode . signatureBytes
+  {-# INLINE smpEncode #-}
+  smpP = decodeSignature <$?> smpP
+  {-# INLINE smpP #-}
 
 instance CryptoSignature ASignature where
   signatureBytes (ASignature _ sig) = signatureBytes sig
+  {-# INLINE signatureBytes #-}
   decodeSignature s
     | B.length s == Ed25519.signatureSize =
         ASignature SEd25519 . SignatureEd25519 <$> ed Ed25519.signature s
@@ -801,6 +815,7 @@ instance CryptoSignature ASignature where
 
 instance CryptoSignature (Maybe ASignature) where
   signatureBytes = maybe "" signatureBytes
+  {-# INLINE signatureBytes #-}
   decodeSignature s
     | B.null s = Right Nothing
     | otherwise = Just <$> decodeSignature s
@@ -809,6 +824,7 @@ instance AlgorithmI a => CryptoSignature (Signature a) where
   signatureBytes = \case
     SignatureEd25519 s -> BA.convert s
     SignatureEd448 s -> BA.convert s
+  {-# INLINE signatureBytes #-}
   decodeSignature s = do
     ASignature _ sig <- decodeSignature s
     checkAlgorithm sig
@@ -819,25 +835,31 @@ instance SignatureSize (Signature a) where
   signatureSize = \case
     SignatureEd25519 _ -> Ed25519.signatureSize
     SignatureEd448 _ -> Ed448.signatureSize
+  {-# INLINE signatureSize #-}
 
 instance SignatureSize ASignature where
   signatureSize (ASignature _ s) = signatureSize s
+  {-# INLINE signatureSize #-}
 
 instance SignatureSize APrivateSignKey where
   signatureSize (APrivateSignKey _ k) = signatureSize k
+  {-# INLINE signatureSize #-}
 
 instance SignatureSize APublicVerifyKey where
   signatureSize (APublicVerifyKey _ k) = signatureSize k
+  {-# INLINE signatureSize #-}
 
 instance SignatureAlgorithm a => SignatureSize (PrivateKey a) where
   signatureSize = \case
     PrivateKeyEd25519 _ _ -> Ed25519.signatureSize
     PrivateKeyEd448 _ _ -> Ed448.signatureSize
+  {-# INLINE signatureSize #-}
 
 instance SignatureAlgorithm a => SignatureSize (PublicKey a) where
   signatureSize = \case
     PublicKeyEd25519 _ -> Ed25519.signatureSize
     PublicKeyEd448 _ -> Ed448.signatureSize
+  {-# INLINE signatureSize #-}
 
 -- | Various cryptographic or related errors.
 data CryptoError
@@ -887,6 +909,7 @@ x448_size = 448 `quot` 8
 validSignatureSize :: Int -> Bool
 validSignatureSize n =
   n == Ed25519.signatureSize || n == Ed448.signatureSize
+{-# INLINE validSignatureSize #-}
 
 -- | AES key newtype.
 newtype Key = Key {unKey :: ByteString}
@@ -961,10 +984,22 @@ instance FromField KeyHash where fromField = blobFieldDecoder $ parseAll strP
 -- | SHA256 digest.
 sha256Hash :: ByteString -> ByteString
 sha256Hash = BA.convert . (hash :: ByteString -> Digest SHA256)
+{-# INLINE sha256Hash #-}
 
 -- | SHA512 digest.
 sha512Hash :: ByteString -> ByteString
 sha512Hash = BA.convert . (hash :: ByteString -> Digest SHA512)
+{-# INLINE sha512Hash #-}
+
+-- | SHA3-256 digest.
+sha3_256 :: ByteString -> ByteString
+sha3_256 = BA.convert . (hash :: ByteString -> Digest SHA3_256)
+{-# INLINE sha3_256 #-}
+
+-- | SHA3-384 digest.
+sha3_384 :: ByteString -> ByteString
+sha3_384 = BA.convert . (hash :: ByteString -> Digest SHA3_384)
+{-# INLINE sha3_384 #-}
 
 -- | AEAD-GCM encryption with associated data.
 --
@@ -981,6 +1016,7 @@ encryptAEAD aesKey ivBytes paddedLen ad msg = do
 -- This function requires 12 bytes IV, it does not transform IV.
 encryptAESNoPad :: Key -> GCMIV -> ByteString -> ExceptT CryptoError IO (AuthTag, ByteString)
 encryptAESNoPad key iv = encryptAEADNoPad key iv ""
+{-# INLINE encryptAESNoPad #-}
 
 encryptAEADNoPad :: Key -> GCMIV -> ByteString -> ByteString -> ExceptT CryptoError IO (AuthTag, ByteString)
 encryptAEADNoPad aesKey ivBytes ad msg = do
@@ -1002,6 +1038,7 @@ decryptAEAD aesKey ivBytes ad msg (AuthTag authTag) = do
 -- This function requires 12 bytes IV, it does not transform IV.
 decryptAESNoPad :: Key -> GCMIV -> ByteString -> AuthTag -> ExceptT CryptoError IO ByteString
 decryptAESNoPad key iv = decryptAEADNoPad key iv ""
+{-# INLINE decryptAESNoPad #-}
 
 decryptAEADNoPad :: Key -> GCMIV -> ByteString -> ByteString -> AuthTag -> ExceptT CryptoError IO ByteString
 decryptAEADNoPad aesKey iv ad msg (AuthTag tag) = do
@@ -1054,6 +1091,7 @@ maxLenBS s
 
 unsafeMaxLenBS :: forall i. KnownNat i => ByteString -> MaxLenBS i
 unsafeMaxLenBS = MLBS
+{-# INLINE unsafeMaxLenBS #-}
 
 padMaxLenBS :: forall i. KnownNat i => MaxLenBS i -> MaxLenBS (i + 2)
 padMaxLenBS (MLBS msg) = MLBS $ encodeWord16 (fromIntegral len) <> msg <> B.replicate padLen '#'
@@ -1066,6 +1104,7 @@ appendMaxLenBS (MLBS s1) (MLBS s2) = MLBS $ s1 <> s2
 
 maxLength :: forall i. KnownNat i => Int
 maxLength = fromIntegral (natVal $ Proxy @i)
+{-# INLINE maxLength #-}
 
 -- this function requires 16 bytes IV, it transforms IV in cryptonite_aes_gcm_init here:
 -- https://github.com/haskell-crypto/cryptonite/blob/master/cbits/cryptonite_aes.c
@@ -1086,12 +1125,15 @@ initAEADGCM (Key aesKey) (GCMIV ivBytes) = cryptoFailable $ do
 -- | Random AES256 key.
 randomAesKey :: TVar ChaChaDRG -> STM Key
 randomAesKey = fmap Key . randomBytes aesKeySize
+{-# INLINE randomAesKey #-}
 
 randomGCMIV :: TVar ChaChaDRG -> STM GCMIV
 randomGCMIV = fmap GCMIV . randomBytes gcmIVSize
+{-# INLINE randomGCMIV #-}
 
 ivSize :: forall c. AES.BlockCipher c => Int
 ivSize = AES.blockSize (undefined :: c)
+{-# INLINE ivSize #-}
 
 gcmIVSize :: Int
 gcmIVSize = 12
@@ -1101,6 +1143,7 @@ makeIV bs = maybeError CryptoIVError $ AES.makeIV bs
 
 maybeError :: CryptoError -> Maybe a -> ExceptT CryptoError IO a
 maybeError e = maybe (throwE e) return
+{-# INLINE maybeError #-}
 
 cryptoFailable :: CE.CryptoFailable a -> ExceptT CryptoError IO a
 cryptoFailable = liftEither . first AESCipherError . CE.eitherCryptoError
@@ -1111,12 +1154,15 @@ cryptoFailable = liftEither . first AESCipherError . CE.eitherCryptoError
 sign' :: SignatureAlgorithm a => PrivateKey a -> ByteString -> Signature a
 sign' (PrivateKeyEd25519 pk k) msg = SignatureEd25519 $ Ed25519.sign pk k msg
 sign' (PrivateKeyEd448 pk k) msg = SignatureEd448 $ Ed448.sign pk k msg
+{-# INLINE sign' #-}
 
 sign :: APrivateSignKey -> ByteString -> ASignature
 sign (APrivateSignKey a k) = ASignature a . sign' k
+{-# INLINE sign #-}
 
 signCertificate :: APrivateSignKey -> Certificate -> SignedCertificate
 signCertificate = signX509
+{-# INLINE signCertificate #-}
 
 signX509 :: (ASN1Object o, Eq o, Show o) => APrivateSignKey -> o -> SignedExact o
 signX509 key = fst . objectToSignedExact f
@@ -1141,6 +1187,7 @@ verifyX509 key exact = do
 
 certificateFingerprint :: SignedCertificate -> KeyHash
 certificateFingerprint = signedFingerprint
+{-# INLINE certificateFingerprint #-}
 
 signedFingerprint :: (ASN1Object o, Eq o, Show o) => SignedExact o -> KeyHash
 signedFingerprint o = KeyHash fp
@@ -1154,16 +1201,20 @@ instance SignatureAlgorithm a => SignatureAlgorithmX509 (SAlgorithm a) where
   signatureAlgorithmX509 = \case
     SEd25519 -> SignatureALG_IntrinsicHash PubKeyALG_Ed25519
     SEd448 -> SignatureALG_IntrinsicHash PubKeyALG_Ed448
+  {-# INLINE signatureAlgorithmX509 #-}
 
 instance SignatureAlgorithmX509 APrivateSignKey where
   signatureAlgorithmX509 (APrivateSignKey a _) = signatureAlgorithmX509 a
+  {-# INLINE signatureAlgorithmX509 #-}
 
 instance SignatureAlgorithmX509 APublicVerifyKey where
   signatureAlgorithmX509 (APublicVerifyKey a _) = signatureAlgorithmX509 a
+  {-# INLINE signatureAlgorithmX509 #-}
 
 -- | An instance for 'ASignatureKeyPair' / ('PublicKeyType' pk, pk), without touching its type family.
 instance SignatureAlgorithmX509 pk => SignatureAlgorithmX509 (a, pk) where
   signatureAlgorithmX509 = signatureAlgorithmX509 . snd
+  {-# INLINE signatureAlgorithmX509 #-}
 
 -- | A wrapper to marshall signed ASN1 objects, like certificates.
 newtype SignedObject a = SignedObject {getSignedExact :: SignedExact a}
@@ -1198,6 +1249,7 @@ certChainP = do
 verify' :: SignatureAlgorithm a => PublicKey a -> Signature a -> ByteString -> Bool
 verify' (PublicKeyEd25519 k) (SignatureEd25519 sig) msg = Ed25519.verify k msg sig
 verify' (PublicKeyEd448 k) (SignatureEd448 sig) msg = Ed448.verify k msg sig
+{-# INLINE verify' #-}
 
 verify :: APublicVerifyKey -> ASignature -> ByteString -> Bool
 verify (APublicVerifyKey a k) (ASignature a' sig) msg = case testEquality a a' of
@@ -1207,25 +1259,35 @@ verify (APublicVerifyKey a k) (ASignature a' sig) msg = case testEquality a a' o
 dh' :: DhAlgorithm a => PublicKey a -> PrivateKey a -> DhSecret a
 dh' (PublicKeyX25519 k) (PrivateKeyX25519 pk _) = DhSecretX25519 $ X25519.dh k pk
 dh' (PublicKeyX448 k) (PrivateKeyX448 pk _) = DhSecretX448 $ X448.dh k pk
+{-# INLINE dh' #-}
 
 -- | NaCl @crypto_box@ encrypt with padding with a shared DH secret and 192-bit nonce.
 cbEncrypt :: DhSecret X25519 -> CbNonce -> ByteString -> Int -> Either CryptoError ByteString
 cbEncrypt (DhSecretX25519 secret) = sbEncrypt_ secret
+{-# INLINE cbEncrypt #-}
 
 -- | NaCl @crypto_box@ encrypt with a shared DH secret and 192-bit nonce (without padding).
 cbEncryptNoPad :: DhSecret X25519 -> CbNonce -> ByteString -> ByteString
 cbEncryptNoPad (DhSecretX25519 secret) (CbNonce nonce) = cryptoBox secret nonce
+{-# INLINE cbEncryptNoPad #-}
 
 -- | NaCl @secret_box@ encrypt with a symmetric 256-bit key and 192-bit nonce.
 sbEncrypt :: SbKey -> CbNonce -> ByteString -> Int -> Either CryptoError ByteString
 sbEncrypt (SbKey key) = sbEncrypt_ key
+{-# INLINE sbEncrypt #-}
 
 sbEncrypt_ :: ByteArrayAccess key => key -> CbNonce -> ByteString -> Int -> Either CryptoError ByteString
 sbEncrypt_ secret (CbNonce nonce) msg paddedLen = cryptoBox secret nonce <$> pad msg paddedLen
+{-# INLINE sbEncrypt_ #-}
+
+sbEncryptNoPad :: SbKey -> CbNonce -> ByteString -> ByteString
+sbEncryptNoPad (SbKey key) (CbNonce nonce) = cryptoBox key nonce
+{-# INLINE sbEncryptNoPad #-}
 
 -- | NaCl @crypto_box@ encrypt with a shared DH secret and 192-bit nonce.
 cbEncryptMaxLenBS :: KnownNat i => DhSecret X25519 -> CbNonce -> MaxLenBS i -> ByteString
 cbEncryptMaxLenBS (DhSecretX25519 secret) (CbNonce nonce) = cryptoBox secret nonce . unMaxLenBS . padMaxLenBS
+{-# INLINE cbEncryptMaxLenBS #-}
 
 cryptoBox :: ByteArrayAccess key => key -> ByteString -> ByteString -> ByteString
 cryptoBox secret nonce s = BA.convert tag <> c
@@ -1236,18 +1298,26 @@ cryptoBox secret nonce s = BA.convert tag <> c
 -- | NaCl @crypto_box@ decrypt with a shared DH secret and 192-bit nonce.
 cbDecrypt :: DhSecret X25519 -> CbNonce -> ByteString -> Either CryptoError ByteString
 cbDecrypt (DhSecretX25519 secret) = sbDecrypt_ secret
+{-# INLINE cbDecrypt #-}
 
 -- | NaCl @crypto_box@ decrypt with a shared DH secret and 192-bit nonce (without unpadding).
 cbDecryptNoPad :: DhSecret X25519 -> CbNonce -> ByteString -> Either CryptoError ByteString
 cbDecryptNoPad (DhSecretX25519 secret) = sbDecryptNoPad_ secret
+{-# INLINE cbDecryptNoPad #-}
 
 -- | NaCl @secret_box@ decrypt with a symmetric 256-bit key and 192-bit nonce.
 sbDecrypt :: SbKey -> CbNonce -> ByteString -> Either CryptoError ByteString
 sbDecrypt (SbKey key) = sbDecrypt_ key
+{-# INLINE sbDecrypt #-}
 
 -- | NaCl @crypto_box@ decrypt with a shared DH secret and 192-bit nonce.
 sbDecrypt_ :: ByteArrayAccess key => key -> CbNonce -> ByteString -> Either CryptoError ByteString
 sbDecrypt_ secret nonce = unPad <=< sbDecryptNoPad_ secret nonce
+{-# INLINE sbDecrypt_ #-}
+
+sbDecryptNoPad :: SbKey -> CbNonce -> ByteString -> Either CryptoError ByteString
+sbDecryptNoPad (SbKey key) = sbDecryptNoPad_ key
+{-# INLINE sbDecryptNoPad #-}
 
 -- | NaCl @crypto_box@ decrypt with a shared DH secret and 192-bit nonce (without unpadding).
 sbDecryptNoPad_ :: ByteArrayAccess key => key -> CbNonce -> ByteString -> Either CryptoError ByteString
@@ -1356,20 +1426,23 @@ newtype SbChainKey = SecretBoxChainKey {unSbChainKey :: ByteString}
 sbcInit :: ByteArrayAccess secret => ByteString -> secret -> (SbChainKey, SbChainKey)
 sbcInit salt secret = (SecretBoxChainKey ck1, SecretBoxChainKey ck2)
   where
-    prk = H.extract salt secret :: H.PRK SHA512
-    out = H.expand prk ("SimpleXSbChainInit" :: ByteString) 64
-    (ck1, ck2) = B.splitAt 32 out
+    (ck1, ck2) = B.splitAt 32 $ hkdf salt secret "SimpleXSbChainInit" 64
 
 type SbKeyNonce = (SbKey, CbNonce)
 
 sbcHkdf :: SbChainKey -> (SbKeyNonce, SbChainKey)
 sbcHkdf (SecretBoxChainKey ck) = ((SecretBoxKey sk, CryptoBoxNonce nonce), SecretBoxChainKey ck')
   where
-    prk = H.extract B.empty ck :: H.PRK SHA512
-    out = H.expand prk ("SimpleXSbChain" :: ByteString) 88 -- = 32 (new chain key) + 32 (secret_box key) + 24 (nonce)
+    out = hkdf "" ck "SimpleXSbChain" 88 -- = 32 (new chain key) + 32 (secret_box key) + 24 (nonce)
     (ck', rest) = B.splitAt 32 out
     (sk, nonce) = B.splitAt 32 rest
 
+hkdf :: ByteArrayAccess secret => ByteString -> secret -> ByteString -> Int -> ByteString
+hkdf salt ikm info n =
+  let prk = H.extract salt ikm :: H.PRK SHA512
+   in H.expand prk info n
+{-# INLINE hkdf #-}
+
 xSalsa20 :: ByteArrayAccess key => key -> ByteString -> ByteString -> (ByteString, ByteString)
 xSalsa20 secret nonce msg = (rs, msg')
   where
diff --git a/src/Simplex/Messaging/Crypto/Ratchet.hs b/src/Simplex/Messaging/Crypto/Ratchet.hs
index 5ac052ad8e..576e78c037 100644
--- a/src/Simplex/Messaging/Crypto/Ratchet.hs
+++ b/src/Simplex/Messaging/Crypto/Ratchet.hs
@@ -94,8 +94,6 @@ import Control.Monad.Except
 import Control.Monad.IO.Class (liftIO)
 import Control.Monad.Trans.Except
 import Crypto.Cipher.AES (AES256)
-import Crypto.Hash (SHA512)
-import qualified Crypto.KDF.HKDF as H
 import Crypto.Random (ChaChaDRG)
 import Data.Aeson (FromJSON (..), ToJSON (..))
 import qualified Data.Aeson as J
@@ -308,11 +306,13 @@ instance (RatchetKEMStateI s, AlgorithmI a) => StrEncoding (E2ERatchetParamsUri
         | otherwise = case kem of
             RKParamsProposed k -> [("kem_key", strEncode k)]
             RKParamsAccepted ct k -> [("kem_ct", strEncode ct), ("kem_key", strEncode k)]
-  strP = toParamsURI <$?> strP
-    where
-      toParamsURI = \case
-        AE2ERatchetParamsUri _ (E2ERatchetParamsUri vr k1 k2 Nothing) -> Right $ E2ERatchetParamsUri vr k1 k2 Nothing
-        AE2ERatchetParamsUri _ ps -> checkRatchetKEMState ps
+  strP = toE2ERatchetParamsUri <$?> strP
+  {-# INLINE strP #-}
+    
+toE2ERatchetParamsUri :: RatchetKEMStateI s => AE2ERatchetParamsUri a -> Either String (E2ERatchetParamsUri s a)
+toE2ERatchetParamsUri = \case
+  AE2ERatchetParamsUri _ (E2ERatchetParamsUri vr k1 k2 Nothing) -> Right $ E2ERatchetParamsUri vr k1 k2 Nothing
+  AE2ERatchetParamsUri _ ps -> checkRatchetKEMState ps
 
 instance AlgorithmI a => StrEncoding (AE2ERatchetParamsUri a) where
   strEncode (AE2ERatchetParamsUri _ ps) = strEncode ps
@@ -342,6 +342,33 @@ instance StrEncoding AnyE2ERatchetParamsUri where
         Nothing -> ARKP SRKSProposed $ RKParamsProposed k
         Just ct -> ARKP SRKSAccepted $ RKParamsAccepted ct k
 
+instance (RatchetKEMStateI s, AlgorithmI a) => Encoding (E2ERatchetParamsUri s a) where
+  smpEncode (E2ERatchetParamsUri vr k1 k2 kem_) = smpEncode (vr, k1, k2, kem_)
+  {-# INLINE smpEncode #-}
+  smpP = toE2ERatchetParamsUri <$?> smpP
+  {-# INLINE smpP #-}
+
+instance AlgorithmI a => Encoding (AE2ERatchetParamsUri a) where
+  smpEncode (AE2ERatchetParamsUri _ ps) = smpEncode ps
+  {-# INLINE smpEncode #-}
+  smpP = (\(AnyE2ERatchetParamsUri s _ ps) -> AE2ERatchetParamsUri s <$> checkAlgorithm ps) <$?> smpP
+  {-# INLINE smpP #-}
+
+instance Encoding AnyE2ERatchetParamsUri where
+  smpEncode (AnyE2ERatchetParamsUri _ _ ps) = smpEncode ps
+  {-# INLINE smpEncode #-}
+  smpP = do
+    vr <- smpP @VersionRangeE2E
+    APublicDhKey a k1 <- smpP
+    APublicDhKey a' k2 <- smpP
+    case testEquality a a' of
+      Nothing -> fail "bad e2e params: different key algorithms"
+      Just Refl ->
+        let result = \case
+              Just (ARKP s kem) -> AnyE2ERatchetParamsUri s a $ E2ERatchetParamsUri vr k1 k2 (Just kem)
+              Nothing -> AnyE2ERatchetParamsUri SRKSProposed a $ E2ERatchetParamsUri vr k1 k2 Nothing
+         in result <$> smpP
+
 type RcvE2ERatchetParams a = E2ERatchetParams 'RKSProposed a
 
 type SndE2ERatchetParams a = AE2ERatchetParams a
@@ -1130,8 +1157,7 @@ chainKdf (RatchetKey ck) =
 hkdf3 :: ByteString -> ByteString -> ByteString -> (ByteString, ByteString, ByteString)
 hkdf3 salt ikm info = (s1, s2, s3)
   where
-    prk = H.extract salt ikm :: H.PRK SHA512
-    out = H.expand prk info 96
+    out = hkdf salt ikm info 96
     (s1, rest) = B.splitAt 32 out
     (s2, s3) = B.splitAt 32 rest
 
diff --git a/src/Simplex/Messaging/Crypto/ShortLink.hs b/src/Simplex/Messaging/Crypto/ShortLink.hs
new file mode 100644
index 0000000000..8ea38f9fe0
--- /dev/null
+++ b/src/Simplex/Messaging/Crypto/ShortLink.hs
@@ -0,0 +1,102 @@
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE DuplicateRecordFields #-}
+{-# LANGUAGE GADTs #-}
+{-# LANGUAGE MultiWayIf #-}
+{-# LANGUAGE NamedFieldPuns #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE TupleSections #-}
+{-# LANGUAGE TypeApplications #-}
+
+module Simplex.Messaging.Crypto.ShortLink
+  ( contactShortLinkKdf,
+    invShortLinkKdf,
+    encodeSignLinkData,
+    encodeSignUserData,
+    encryptLinkData,
+    encryptUserData,
+    decryptLinkData,
+  )
+where
+
+import Control.Concurrent.STM
+import Control.Monad.Except
+import Control.Monad.IO.Class
+import Crypto.Random (ChaChaDRG)
+import Data.Bifunctor (first)
+import Data.Bitraversable (bimapM)
+import Data.ByteString (ByteString)
+import qualified Data.ByteString as B
+import Simplex.Messaging.Agent.Client (cryptoError)
+import Simplex.Messaging.Agent.Protocol
+import qualified Simplex.Messaging.Crypto as C
+import Simplex.Messaging.Encoding
+import Simplex.Messaging.Protocol (EntityId (..), LinkId, EncDataBytes (..), QueueLinkData)
+import Simplex.Messaging.Util (liftEitherWith)
+
+fixedDataPaddedLength :: Int
+fixedDataPaddedLength = 2008 -- 2048 - 24 (nonce) - 16 (auth tag)
+
+userDataPaddedLength :: Int
+userDataPaddedLength = 13784 -- 13824 - 24 - 16
+
+contactShortLinkKdf :: LinkKey -> (LinkId, C.SbKey)
+contactShortLinkKdf (LinkKey k) =
+  let (lnkId, sbKey) = B.splitAt 24 $ C.hkdf "" k "SimpleXContactLink" 56
+   in (EntityId lnkId, C.unsafeSbKey sbKey)
+
+invShortLinkKdf :: LinkKey -> C.SbKey
+invShortLinkKdf (LinkKey k) = C.unsafeSbKey $ C.hkdf "" k "SimpleXInvLink" 32
+
+encodeSignLinkData :: forall c. ConnectionModeI c => C.KeyPair 'C.Ed25519 -> VersionRangeSMPA -> ConnectionRequestUri c -> ConnInfo -> (LinkKey, (ByteString, ByteString))
+encodeSignLinkData (rootKey, pk) agentVRange connReq userData =
+  let fd = smpEncode FixedLinkData {agentVRange, rootKey, connReq}
+      md = smpEncode $ connLinkData @c agentVRange userData
+   in (LinkKey (C.sha3_256 fd), (encodeSign pk fd, encodeSign pk md))
+
+encodeSignUserData :: C.PrivateKeyEd25519 -> VersionRangeSMPA -> ConnInfo -> ByteString
+encodeSignUserData pk agentVRange userData =
+  encodeSign pk $ smpEncode $ connLinkData @'CMContact agentVRange userData
+
+connLinkData :: forall c. ConnectionModeI c => VersionRangeSMPA -> ConnInfo -> ConnLinkData c
+connLinkData agentVRange userData = case sConnectionMode @c of
+  SCMInvitation -> InvitationLinkData agentVRange userData
+  SCMContact -> ContactLinkData {agentVRange, direct = True, owners = [], relays = [], userData}
+
+encodeSign :: C.PrivateKeyEd25519 -> ByteString -> ByteString
+encodeSign pk s = smpEncode (C.sign' pk s) <> s
+
+encryptLinkData :: TVar ChaChaDRG -> C.SbKey -> (ByteString, ByteString) -> ExceptT AgentErrorType IO QueueLinkData
+encryptLinkData g k = bimapM (encrypt fixedDataPaddedLength) (encrypt userDataPaddedLength)
+  where
+    encrypt len = encryptData g k len
+
+encryptUserData :: TVar ChaChaDRG -> C.SbKey -> ByteString -> ExceptT AgentErrorType IO EncDataBytes
+encryptUserData g k s = encryptData g k userDataPaddedLength s
+
+encryptData :: TVar ChaChaDRG -> C.SbKey -> Int -> ByteString -> ExceptT AgentErrorType IO EncDataBytes
+encryptData g k len s = do
+  nonce <- liftIO $ atomically $ C.randomCbNonce g
+  ct <- liftEitherWith cryptoError $ C.sbEncrypt k nonce s len
+  pure $ EncDataBytes $ smpEncode nonce <> ct
+
+decryptLinkData :: forall c. ConnectionModeI c => LinkKey -> C.SbKey -> QueueLinkData -> Either AgentErrorType (ConnectionRequestUri c, ConnLinkData c)
+decryptLinkData linkKey k (encFD, encMD) = do
+  (sig1, fd) <- decrypt encFD
+  (sig2, md) <- decrypt encMD
+  FixedLinkData {rootKey, connReq} <- decode fd
+  md' <- decode @(ConnLinkData c) md
+  if
+    | LinkKey (C.sha3_256 fd) /= linkKey -> linkErr "link data hash"
+    | not (C.verify' rootKey sig1 fd) -> linkErr "link data signature"
+    | not (C.verify' rootKey sig2 md) -> linkErr "user data signature"
+    | otherwise -> Right (connReq, md')
+  where
+    decrypt (EncDataBytes d) = do
+      (nonce, Tail ct) <- decode d
+      (sig, Tail s) <- decode =<< first cryptoError (C.sbDecrypt k nonce ct)
+      pure (sig, s)
+    decode :: Encoding a => ByteString -> Either AgentErrorType a
+    decode = msgErr . smpDecode
+    msgErr = first (const $ AGENT A_MESSAGE)
+    linkErr = Left . AGENT . A_LINK
diff --git a/src/Simplex/Messaging/Protocol.hs b/src/Simplex/Messaging/Protocol.hs
index 1222468682..cb2eea43bf 100644
--- a/src/Simplex/Messaging/Protocol.hs
+++ b/src/Simplex/Messaging/Protocol.hs
@@ -57,7 +57,13 @@ module Simplex.Messaging.Protocol
     ProtocolEncoding (..),
     Command (..),
     SubscriptionMode (..),
-    SenderCanSecure,
+    NewQueueReq (..),
+    QueueReqData (..),
+    QueueMode (..),
+    QueueLinkData,
+    EncFixedDataBytes,
+    EncUserDataBytes,
+    EncDataBytes (..),
     Party (..),
     Cmd (..),
     DirectParty,
@@ -108,6 +114,7 @@ module Simplex.Messaging.Protocol
     QueueId,
     RecipientId,
     SenderId,
+    LinkId,
     NotifierId,
     RcvPrivateAuthKey,
     RcvPublicAuthKey,
@@ -140,6 +147,8 @@ module Simplex.Messaging.Protocol
     MsgFlags (..),
     initialSMPClientVersion,
     currentSMPClientVersion,
+    senderCanSecure,
+    queueReqMode,
     userProtocol,
     rcvMessageMeta,
     noMsgFlags,
@@ -161,6 +170,7 @@ module Simplex.Messaging.Protocol
     legacyStrEncodeServer,
     srvHostnamesSMPClientVersion,
     sndAuthKeySMPClientVersion,
+    shortLinksSMPClientVersion,
     sameSrvAddr,
     sameSrvAddr',
     noAuthSrv,
@@ -215,6 +225,7 @@ import GHC.TypeLits (ErrorMessage (..), TypeError, type (+))
 import qualified GHC.TypeLits as TE
 import qualified GHC.TypeLits as Type
 import Network.Socket (ServiceName)
+import Simplex.Messaging.Agent.Store.DB (Binary (..), FromField (..), ToField (..))
 import qualified Simplex.Messaging.Crypto as C
 import Simplex.Messaging.Encoding
 import Simplex.Messaging.Encoding.String
@@ -230,6 +241,8 @@ import Simplex.Messaging.Version.Internal
 -- SMP client protocol version history:
 -- 1 - binary protocol encoding (1/1/2022)
 -- 2 - multiple server hostnames and versioned queue addresses (8/12/2022)
+-- 3 - faster handshake: SKEY command for sender to secure queue (6/30/2024, SMP protocol version 9)
+-- 4 - short connection links with stored data (3/30/2025, SMP protocol version 15)
 
 data SMPClientVersion
 
@@ -251,8 +264,11 @@ srvHostnamesSMPClientVersion = VersionSMPC 2
 sndAuthKeySMPClientVersion :: VersionSMPC
 sndAuthKeySMPClientVersion = VersionSMPC 3
 
+shortLinksSMPClientVersion :: VersionSMPC
+shortLinksSMPClientVersion = VersionSMPC 4
+
 currentSMPClientVersion :: VersionSMPC
-currentSMPClientVersion = VersionSMPC 3
+currentSMPClientVersion = VersionSMPC 4
 
 supportedSMPClientVRange :: VersionRangeSMPC
 supportedSMPClientVRange = mkVersionRange initialSMPClientVersion currentSMPClientVersion
@@ -281,7 +297,7 @@ e2eEncMessageLength :: Int
 e2eEncMessageLength = 16000 -- 15988 .. 16005
 
 -- | SMP protocol clients
-data Party = Recipient | Sender | Notifier | ProxiedClient
+data Party = Recipient | Sender | Notifier | LinkClient | ProxiedClient
   deriving (Show)
 
 -- | Singleton types for SMP protocol clients
@@ -289,12 +305,14 @@ data SParty :: Party -> Type where
   SRecipient :: SParty Recipient
   SSender :: SParty Sender
   SNotifier :: SParty Notifier
+  SSenderLink :: SParty LinkClient 
   SProxiedClient :: SParty ProxiedClient
 
 instance TestEquality SParty where
   testEquality SRecipient SRecipient = Just Refl
   testEquality SSender SSender = Just Refl
   testEquality SNotifier SNotifier = Just Refl
+  testEquality SSenderLink SSenderLink = Just Refl
   testEquality SProxiedClient SProxiedClient = Just Refl
   testEquality _ _ = Nothing
 
@@ -308,12 +326,15 @@ instance PartyI Sender where sParty = SSender
 
 instance PartyI Notifier where sParty = SNotifier
 
+instance PartyI LinkClient where sParty = SSenderLink
+
 instance PartyI ProxiedClient where sParty = SProxiedClient
 
 type family DirectParty (p :: Party) :: Constraint where
   DirectParty Recipient = ()
   DirectParty Sender = ()
   DirectParty Notifier = ()
+  DirectParty LinkClient = ()
   DirectParty p =
     (Int ~ Bool, TypeError (Type.Text "Party " :<>: ShowType p :<>: Type.Text " is not direct"))
 
@@ -377,6 +398,8 @@ type SenderId = QueueId
 -- | SMP queue ID for notifications.
 type NotifierId = QueueId
 
+type LinkId = QueueId
+
 -- | SMP queue ID on the server.
 type QueueId = EntityId
 
@@ -395,9 +418,12 @@ data Command (p :: Party) where
   -- v6 of SMP servers only support signature algorithm for command authorization.
   -- v7 of SMP servers additionally support additional layer of authenticated encryption.
   -- RcvPublicAuthKey is defined as C.APublicKey - it can be either signature or DH public keys.
-  NEW :: RcvPublicAuthKey -> RcvPublicDhKey -> Maybe BasicAuth -> SubscriptionMode -> SenderCanSecure -> Command Recipient
+  NEW :: NewQueueReq -> Command Recipient
   SUB :: Command Recipient
   KEY :: SndPublicAuthKey -> Command Recipient
+  RKEY :: NonEmpty RcvPublicAuthKey -> Command Recipient
+  LSET :: LinkId -> QueueLinkData -> Command Recipient
+  LDEL :: Command Recipient
   NKEY :: NtfPublicAuthKey -> RcvNtfPublicDhKey -> Command Recipient
   NDEL :: Command Recipient
   GET :: Command Recipient
@@ -411,6 +437,9 @@ data Command (p :: Party) where
   -- SEND :: MsgBody -> Command Sender
   SEND :: MsgFlags -> MsgBody -> Command Sender
   PING :: Command Sender
+  -- Client accessing short links
+  LKEY :: SndPublicAuthKey -> Command LinkClient
+  LGET :: Command LinkClient
   -- SMP notification subscriber commands
   NSUB :: Command Notifier
   PRXY :: SMPServer -> Maybe BasicAuth -> Command ProxiedClient -- request a relay server connection by URI
@@ -427,9 +456,60 @@ data Command (p :: Party) where
 
 deriving instance Show (Command p)
 
+data NewQueueReq = NewQueueReq
+  { rcvAuthKey :: RcvPublicAuthKey,
+    rcvDhKey :: RcvPublicDhKey,
+    auth_ :: Maybe BasicAuth,
+    subMode :: SubscriptionMode,
+    queueReqData :: Maybe QueueReqData
+    -- TODO [notifications]
+    -- ntfCreds :: Maybe NewNtfCreds
+  }
+  deriving (Show)
+
 data SubscriptionMode = SMSubscribe | SMOnlyCreate
   deriving (Eq, Show)
 
+-- SenderId must be computed client-side as `sha3-256(corr_id)`, `corr_id` - a random transmission ID.
+-- The server must verify and reject it if it does not match (and in case of collision).
+-- This allows to include SenderId in FixedDataBytes in full connection request,
+-- and at the same time prevents the possibility of checking whether a queue with a known ID exists.
+data QueueReqData = QRMessaging (Maybe (SenderId, QueueLinkData)) | QRContact (Maybe (LinkId, (SenderId, QueueLinkData)))
+  deriving (Show)
+
+queueReqMode :: QueueReqData -> QueueMode
+queueReqMode = \case
+  QRMessaging _ -> QMMessaging
+  QRContact _ -> QMContact
+
+senderCanSecure :: Maybe QueueMode -> Bool
+senderCanSecure = \case
+  Just QMMessaging -> True
+  _ -> False
+
+type QueueLinkData = (EncFixedDataBytes, EncUserDataBytes)
+
+type EncFixedDataBytes = EncDataBytes
+
+type EncUserDataBytes = EncDataBytes
+
+newtype EncDataBytes = EncDataBytes ByteString
+  deriving (Eq, Show)
+  deriving newtype (FromField, StrEncoding)
+
+instance Encoding EncDataBytes where
+  smpEncode (EncDataBytes s) = smpEncode (Large s)
+  {-# INLINE smpEncode #-}
+  smpP = EncDataBytes . unLarge <$> smpP
+  {-# INLINE smpP #-}
+
+instance ToField EncDataBytes where
+  toField (EncDataBytes s) = toField (Binary s)
+  {-# INLINE toField #-}
+
+-- TODO [notifications]
+-- data NewNtfCreds = NewNtfCreds NtfPublicAuthKey RcvNtfPublicDhKey deriving (Show)
+
 instance StrEncoding SubscriptionMode where
   strEncode = \case
     SMSubscribe -> "subscribe"
@@ -449,7 +529,20 @@ instance Encoding SubscriptionMode where
       'C' -> pure SMOnlyCreate
       _ -> fail "bad SubscriptionMode"
 
-type SenderCanSecure = Bool
+instance Encoding QueueReqData where
+  smpEncode = \case
+    QRMessaging d -> smpEncode ('M', d)
+    QRContact d -> smpEncode ('C', d)
+  smpP =
+    A.anyChar >>= \case
+      'M' -> QRMessaging <$> smpP
+      'C' -> QRContact <$> smpP
+      _ -> fail "bad QueueReqData"
+
+-- TODO [notifications]
+-- instance Encoding NewNtfCreds where
+--   smpEncode (NewNtfCreds authKey dhKey) = smpEncode (authKey, dhKey)
+--   smpP = NewNtfCreds <$> smpP <*> smpP
 
 newtype EncTransmission = EncTransmission ByteString
   deriving (Show)
@@ -474,6 +567,7 @@ newtype EncFwdTransmission = EncFwdTransmission ByteString
 data BrokerMsg where
   -- SMP broker messages (responses, client messages, notifications)
   IDS :: QueueIdsKeys -> BrokerMsg
+  LNK :: SenderId -> QueueLinkData -> BrokerMsg
   -- MSG v1/2 has to be supported for encoding/decoding
   -- v1: MSG :: MsgId -> SystemTime -> MsgBody -> BrokerMsg
   -- v2: MsgId -> SystemTime -> MsgFlags -> MsgBody -> BrokerMsg
@@ -679,6 +773,9 @@ data CommandTag (p :: Party) where
   NEW_ :: CommandTag Recipient
   SUB_ :: CommandTag Recipient
   KEY_ :: CommandTag Recipient
+  RKEY_ :: CommandTag Recipient
+  LSET_ :: CommandTag Recipient
+  LDEL_ :: CommandTag Recipient
   NKEY_ :: CommandTag Recipient
   NDEL_ :: CommandTag Recipient
   GET_ :: CommandTag Recipient
@@ -689,6 +786,8 @@ data CommandTag (p :: Party) where
   SKEY_ :: CommandTag Sender
   SEND_ :: CommandTag Sender
   PING_ :: CommandTag Sender
+  LKEY_ :: CommandTag LinkClient
+  LGET_ :: CommandTag LinkClient
   PRXY_ :: CommandTag ProxiedClient
   PFWD_ :: CommandTag ProxiedClient
   RFWD_ :: CommandTag Sender
@@ -702,6 +801,7 @@ deriving instance Show CmdTag
 
 data BrokerMsgTag
   = IDS_
+  | LNK_
   | MSG_
   | NID_
   | NMSG_
@@ -729,6 +829,9 @@ instance PartyI p => Encoding (CommandTag p) where
     NEW_ -> "NEW"
     SUB_ -> "SUB"
     KEY_ -> "KEY"
+    RKEY_ -> "RKEY"
+    LSET_ -> "LSET"
+    LDEL_ -> "LDEL"
     NKEY_ -> "NKEY"
     NDEL_ -> "NDEL"
     GET_ -> "GET"
@@ -739,6 +842,8 @@ instance PartyI p => Encoding (CommandTag p) where
     SKEY_ -> "SKEY"
     SEND_ -> "SEND"
     PING_ -> "PING"
+    LKEY_ -> "LKEY"
+    LGET_ -> "LGET"
     PRXY_ -> "PRXY"
     PFWD_ -> "PFWD"
     RFWD_ -> "RFWD"
@@ -750,6 +855,9 @@ instance ProtocolMsgTag CmdTag where
     "NEW" -> Just $ CT SRecipient NEW_
     "SUB" -> Just $ CT SRecipient SUB_
     "KEY" -> Just $ CT SRecipient KEY_
+    "RKEY" -> Just $ CT SRecipient RKEY_
+    "LSET" -> Just $ CT SRecipient LSET_
+    "LDEL" -> Just $ CT SRecipient LDEL_
     "NKEY" -> Just $ CT SRecipient NKEY_
     "NDEL" -> Just $ CT SRecipient NDEL_
     "GET" -> Just $ CT SRecipient GET_
@@ -760,6 +868,8 @@ instance ProtocolMsgTag CmdTag where
     "SKEY" -> Just $ CT SSender SKEY_
     "SEND" -> Just $ CT SSender SEND_
     "PING" -> Just $ CT SSender PING_
+    "LKEY" -> Just $ CT SSenderLink LKEY_
+    "LGET" -> Just $ CT SSenderLink LGET_
     "PRXY" -> Just $ CT SProxiedClient PRXY_
     "PFWD" -> Just $ CT SProxiedClient PFWD_
     "RFWD" -> Just $ CT SSender RFWD_
@@ -776,6 +886,7 @@ instance PartyI p => ProtocolMsgTag (CommandTag p) where
 instance Encoding BrokerMsgTag where
   smpEncode = \case
     IDS_ -> "IDS"
+    LNK_ -> "LNK"
     MSG_ -> "MSG"
     NID_ -> "NID"
     NMSG_ -> "NMSG"
@@ -793,6 +904,7 @@ instance Encoding BrokerMsgTag where
 instance ProtocolMsgTag BrokerMsgTag where
   decodeTag = \case
     "IDS" -> Just IDS_
+    "LNK" -> Just LNK_
     "MSG" -> Just MSG_
     "NID" -> Just NID_
     "NMSG" -> Just NMSG_
@@ -1138,10 +1250,21 @@ data QueueIdsKeys = QIK
   { rcvId :: RecipientId,
     sndId :: SenderId,
     rcvPublicDhKey :: RcvPublicDhKey,
-    sndSecure :: SenderCanSecure
+    queueMode :: Maybe QueueMode, -- TODO remove Maybe when min version is 9 (sndAuthKeySMPVersion)
+    linkId :: Maybe LinkId
+    -- TODO [notifications]
+    -- serverNtfCreds :: Maybe ServerNtfCreds
   }
   deriving (Eq, Show)
 
+-- TODO [notifications]
+-- data ServerNtfCreds = ServerNtfCreds NotifierId RcvNtfPublicDhKey
+--   deriving (Eq, Show)
+
+-- instance Encoding ServerNtfCreds where
+--   smpEncode (ServerNtfCreds nId dhKey) = smpEncode (nId, dhKey)
+--   smpP = ServerNtfCreds <$> smpP <*> smpP
+
 -- | Recipient's private key used by the recipient to authorize (v6: sign, v7: encrypt hash) SMP commands.
 --
 -- Only used by SMP agent, kept here so its definition is close to respective public key.
@@ -1368,14 +1491,18 @@ class ProtocolMsgTag (Tag msg) => ProtocolEncoding v err msg | msg -> err, msg -
 instance PartyI p => ProtocolEncoding SMPVersion ErrorType (Command p) where
   type Tag (Command p) = CommandTag p
   encodeProtocol v = \case
-    NEW rKey dhKey auth_ subMode sndSecure
-      | v >= sndAuthKeySMPVersion -> new <> e (auth_, subMode, sndSecure)
+    NEW NewQueueReq {rcvAuthKey = rKey, rcvDhKey = dhKey, auth_, subMode, queueReqData}
+      | v >= shortLinksSMPVersion -> new <> e (auth_, subMode, queueReqData)
+      | v >= sndAuthKeySMPVersion -> new <> e (auth_, subMode, senderCanSecure (queueReqMode <$> queueReqData))
       | otherwise -> new <> auth <> e subMode
       where
         new = e (NEW_, ' ', rKey, dhKey)
         auth = maybe "" (e . ('A',)) auth_
     SUB -> e SUB_
     KEY k -> e (KEY_, ' ', k)
+    RKEY ks -> e (RKEY_, ' ', ks)
+    LSET lnkId d -> e (LSET_, ' ', lnkId, d)
+    LDEL -> e LDEL_
     NKEY k dhKey -> e (NKEY_, ' ', k, dhKey)
     NDEL -> e NDEL_
     GET -> e GET_
@@ -1387,6 +1514,8 @@ instance PartyI p => ProtocolEncoding SMPVersion ErrorType (Command p) where
     SEND flags msg -> e (SEND_, ' ', flags, ' ', Tail msg)
     PING -> e PING_
     NSUB -> e NSUB_
+    LKEY k -> e (LKEY_, ' ', k)
+    LGET -> e LGET_
     PRXY host auth_ -> e (PRXY_, ' ', host, auth_)
     PFWD fwdV pubKey (EncTransmission s) -> e (PFWD_, ' ', fwdV, pubKey, Tail s)
     RFWD (EncFwdTransmission s) -> e (RFWD_, ' ', Tail s)
@@ -1409,15 +1538,10 @@ instance PartyI p => ProtocolEncoding SMPVersion ErrorType (Command p) where
     SEND {}
       | B.null entId -> Left $ CMD NO_ENTITY
       | otherwise -> Right cmd
-    SKEY _
-      | isNothing auth || B.null entId -> Left $ CMD NO_AUTH
-      | otherwise -> Right cmd
+    LGET -> entityCmd
     PING -> noAuthCmd
     PRXY {} -> noAuthCmd
-    PFWD {}
-      | B.null entId -> Left $ CMD NO_ENTITY
-      | isNothing auth -> Right cmd
-      | otherwise -> Left $ CMD HAS_AUTH
+    PFWD {} -> entityCmd
     RFWD _ -> noAuthCmd
     -- other client commands must have both signature and queue ID
     _
@@ -1429,6 +1553,11 @@ instance PartyI p => ProtocolEncoding SMPVersion ErrorType (Command p) where
       noAuthCmd
         | isNothing auth && B.null entId = Right cmd
         | otherwise = Left $ CMD HAS_AUTH
+      entityCmd :: Either ErrorType (Command p)
+      entityCmd
+        | B.null entId = Left $ CMD NO_ENTITY
+        | isNothing auth = Right cmd
+        | otherwise = Left $ CMD HAS_AUTH
 
 instance ProtocolEncoding SMPVersion ErrorType Cmd where
   type Tag Cmd = CmdTag
@@ -1438,13 +1567,26 @@ instance ProtocolEncoding SMPVersion ErrorType Cmd where
     CT SRecipient tag ->
       Cmd SRecipient <$> case tag of
         NEW_
-          | v >= sndAuthKeySMPVersion -> new <*> smpP <*> smpP <*> smpP
-          | otherwise -> new <*> auth <*> smpP <*> pure False
+          | v >= shortLinksSMPVersion -> NEW <$> new smpP smpP
+          | v >= sndAuthKeySMPVersion -> NEW <$> new smpP (qReq <$> smpP)
+          | otherwise -> NEW <$> new auth (pure Nothing)
           where
-            new = NEW <$> _smpP <*> smpP
+            new p1 p2 = do
+              rcvAuthKey <- _smpP
+              rcvDhKey <- smpP
+              auth_ <- p1
+              subMode <- smpP
+              queueReqData <- p2
+              -- TODO [notifications]
+              -- ntfCreds <- p3
+              pure NewQueueReq {rcvAuthKey, rcvDhKey, auth_, subMode, queueReqData} -- ntfCreds
             auth = optional (A.char 'A' *> smpP)
+            qReq sndSecure = Just $ if sndSecure then QRMessaging Nothing else QRContact Nothing
         SUB_ -> pure SUB
         KEY_ -> KEY <$> _smpP
+        RKEY_ -> RKEY <$> _smpP
+        LSET_ -> LSET <$> _smpP <*> smpP
+        LDEL_ -> pure LDEL
         NKEY_ -> NKEY <$> _smpP <*> smpP
         NDEL_ -> pure NDEL
         GET_ -> pure GET
@@ -1458,6 +1600,10 @@ instance ProtocolEncoding SMPVersion ErrorType Cmd where
         SEND_ -> SEND <$> _smpP <*> (unTail <$> _smpP)
         PING_ -> pure PING
         RFWD_ -> RFWD <$> (EncFwdTransmission . unTail <$> _smpP)
+    CT SSenderLink tag ->
+      Cmd SSenderLink <$> case tag of
+        LKEY_ -> LKEY <$> _smpP
+        LGET_ -> pure LGET
     CT SProxiedClient tag ->
       Cmd SProxiedClient <$> case tag of
         PFWD_ -> PFWD <$> _smpP <*> smpP <*> (EncTransmission . unTail <$> smpP)
@@ -1472,11 +1618,13 @@ instance ProtocolEncoding SMPVersion ErrorType Cmd where
 instance ProtocolEncoding SMPVersion ErrorType BrokerMsg where
   type Tag BrokerMsg = BrokerMsgTag
   encodeProtocol v = \case
-    IDS (QIK rcvId sndId srvDh sndSecure)
-      | v >= sndAuthKeySMPVersion -> ids <> e sndSecure
+    IDS QIK {rcvId, sndId, rcvPublicDhKey = srvDh, queueMode, linkId}
+      | v >= shortLinksSMPVersion -> ids <> e queueMode <> e linkId
+      | v >= sndAuthKeySMPVersion -> ids <> e (senderCanSecure queueMode)
       | otherwise -> ids
       where
         ids = e (IDS_, ' ', rcvId, sndId, srvDh)
+    LNK sId d -> e (LNK_, ' ', sId, d)
     MSG RcvMessage {msgId, msgBody = EncRcvMsgBody body} ->
       e (MSG_, ' ', msgId, Tail body)
     NID nId srvNtfDh -> e (NID_, ' ', nId, srvNtfDh)
@@ -1505,10 +1653,22 @@ instance ProtocolEncoding SMPVersion ErrorType BrokerMsg where
       where
         bodyP = EncRcvMsgBody . unTail <$> smpP
     IDS_
-      | v >= sndAuthKeySMPVersion -> ids smpP
-      | otherwise -> ids $ pure False
+      | v >= shortLinksSMPVersion -> ids smpP smpP
+      | v >= sndAuthKeySMPVersion -> ids (qm <$> smpP) nothing
+      | otherwise -> ids nothing nothing
       where
-        ids p = IDS <$> (QIK <$> _smpP <*> smpP <*> smpP <*> p)
+        qm sndSecure = Just $ if sndSecure then QMMessaging else QMContact
+        nothing = pure Nothing
+        ids p1 p2 = do
+          rcvId <- _smpP
+          sndId <- smpP
+          rcvPublicDhKey <- smpP
+          queueMode <- p1
+          linkId <- p2
+          -- TODO [notifications]
+          -- serverNtfCreds <- p3
+          pure $ IDS QIK {rcvId, sndId, rcvPublicDhKey, queueMode, linkId}
+    LNK_ -> LNK <$> _smpP <*> smpP
     NID_ -> NID <$> _smpP <*> smpP
     NMSG_ -> NMSG <$> _smpP <*> smpP
     PKEY_ -> PKEY <$> _smpP <*> smpP <*> ((,) <$> C.certChainP <*> (C.getSignedExact <$> smpP))
diff --git a/src/Simplex/Messaging/Server.hs b/src/Simplex/Messaging/Server.hs
index 5ba04e8023..32534ccf92 100644
--- a/src/Simplex/Messaging/Server.hs
+++ b/src/Simplex/Messaging/Server.hs
@@ -850,8 +850,8 @@ smpServer started cfg@ServerConfig {transports, transportConfig = tCfg, startOpt
                 q <- liftIO $ getQueueRec st SSender sId
                 liftIO $ hPutStrLn h $ case q of
                   Left e -> "error: " <> show e
-                  Right (_, QueueRec {sndSecure, status, updatedAt}) ->
-                    "status: " <> show status <> ", updatedAt: " <> show updatedAt <> ", sndSecure: " <> show sndSecure
+                  Right (_, QueueRec {queueMode, status, updatedAt}) ->
+                    "status: " <> show status <> ", updatedAt: " <> show updatedAt <> ", queueMode: " <> show queueMode
               CPBlock sId info -> withUserRole $ unliftIO u $ do
                 AMS _ _ (st :: s) <- asks msgStore
                 r <- liftIO $ runExceptT $ do
@@ -1061,13 +1061,15 @@ data VerificationResult s = VRVerified (Maybe (StoreQueue s, QueueRec)) | VRFail
 verifyTransmission :: forall s. MsgStoreClass s => s -> Maybe (THandleAuth 'TServer, C.CbNonce) -> Maybe TransmissionAuth -> ByteString -> QueueId -> Cmd -> M (VerificationResult s)
 verifyTransmission ms auth_ tAuth authorized queueId cmd =
   case cmd of
-    Cmd SRecipient (NEW k _ _ _ _) -> pure $ Nothing `verifiedWith` k
-    Cmd SRecipient _ -> verifyQueue (\q -> Just q `verifiedWith` recipientKey (snd q)) <$> get SRecipient
-    -- SEND will be accepted without authorization before the queue is secured with KEY or SKEY command
-    Cmd SSender (SKEY k) -> verifyQueue (\q -> if maybe True (k ==) (senderKey $ snd q) then Just q `verifiedWith` k else dummyVerify) <$> get SSender
-    Cmd SSender SEND {} -> verifyQueue (\q -> Just q `verified` maybe (isNothing tAuth) verify (senderKey $ snd q)) <$> get SSender
+    Cmd SRecipient (NEW NewQueueReq {rcvAuthKey = k}) -> pure $ Nothing `verifiedWith` k
+    Cmd SRecipient _ -> verifyQueue (\q -> Just q `verifiedWithKeys` recipientKeys (snd q)) <$> get SRecipient
+    Cmd SSender (SKEY k) -> verifySecure SSender k
+    -- SEND will be accepted without authorization before the queue is secured with KEY, SKEY or LSKEY command
+    Cmd SSender SEND {} -> verifyQueue (\q -> if maybe (isNothing tAuth) verify (senderKey $ snd q) then VRVerified (Just q) else VRFailed) <$> get SSender
     Cmd SSender PING -> pure $ VRVerified Nothing
     Cmd SSender RFWD {} -> pure $ VRVerified Nothing
+    Cmd SSenderLink (LKEY k) -> verifySecure SSenderLink k
+    Cmd SSenderLink LGET -> verifyQueue (\q -> if isContact (snd q) then VRVerified (Just q) else VRFailed) <$> get SSenderLink
     -- NSUB will not be accepted without authorization
     Cmd SNotifier NSUB -> verifyQueue (\q -> maybe dummyVerify (\n -> Just q `verifiedWith` notifierKey n) (notifier $ snd q)) <$> get SNotifier
     Cmd SProxiedClient _ -> pure $ VRVerified Nothing
@@ -1076,9 +1078,18 @@ verifyTransmission ms auth_ tAuth authorized queueId cmd =
     dummyVerify = verify (dummyAuthKey tAuth) `seq` VRFailed
     verifyQueue :: ((StoreQueue s, QueueRec) -> VerificationResult s) -> Either ErrorType (StoreQueue s, QueueRec) -> VerificationResult s
     verifyQueue = either (const dummyVerify)
-    verified q cond = if cond then VRVerified q else VRFailed
+    verifySecure :: DirectParty p => SParty p -> SndPublicAuthKey -> M (VerificationResult s)
+    verifySecure p k = verifyQueue (\q -> if k `allowedKey` snd q then Just q `verifiedWith` k else dummyVerify) <$> get p
     verifiedWith :: Maybe (StoreQueue s, QueueRec) -> C.APublicAuthKey -> VerificationResult s
-    verifiedWith q k = q `verified` verify k
+    verifiedWith q_ k = if verify k then VRVerified q_ else VRFailed
+    verifiedWithKeys :: Maybe (StoreQueue s, QueueRec) -> NonEmpty C.APublicAuthKey -> VerificationResult s
+    verifiedWithKeys q_ ks = if any verify ks then VRVerified q_ else VRFailed
+    allowedKey k = \case
+      QueueRec {queueMode = Just QMMessaging, senderKey} -> maybe True (k ==) senderKey
+      _ -> False
+    isContact = \case
+      QueueRec {queueMode = Just QMContact} -> True
+      _ -> False
     get :: DirectParty p => SParty p -> M (Either ErrorType (StoreQueue s, QueueRec))
     get party = liftIO $ getQueueRec ms party queueId
 
@@ -1234,84 +1245,114 @@ client
     processCommand clntVersion (q_, (corrId, entId, cmd)) = case cmd of
       Cmd SProxiedClient command -> processProxiedCmd (corrId, entId, command)
       Cmd SSender command -> Just <$> case command of
-        SKEY sKey ->
-          withQueue $ \q QueueRec {sndSecure} ->
-            (corrId,entId,) <$> if sndSecure then secureQueue_ q sKey else pure $ ERR AUTH
+        SKEY k -> withQueue $ \q qr -> checkMode QMMessaging qr $ secureQueue_ q k
         SEND flags msgBody -> withQueue_ False $ sendMessage flags msgBody
         PING -> pure (corrId, NoEntity, PONG)
         RFWD encBlock -> (corrId, NoEntity,) <$> processForwardedCommand encBlock
+      Cmd SSenderLink command -> Just <$> case command of
+        LKEY k -> withQueue $ \q qr -> checkMode QMMessaging qr $ secureQueue_ q k $>> getQueueLink_ q qr
+        LGET -> withQueue $ \q qr -> checkMode QMContact qr $ getQueueLink_ q qr
       Cmd SNotifier NSUB -> Just <$> subscribeNotifications
       Cmd SRecipient command ->
         Just <$> case command of
-          NEW rKey dhKey auth subMode sndSecure ->
-            ifM
-              allowNew
-              (createQueue rKey dhKey subMode sndSecure)
-              (pure (corrId, entId, ERR AUTH))
+          NEW nqr@NewQueueReq {auth_} ->
+            ifM allowNew (createQueue nqr) (pure (corrId, entId, ERR AUTH))
             where
               allowNew = do
                 ServerConfig {allowNewQueues, newQueueBasicAuth} <- asks config
-                pure $ allowNewQueues && maybe True ((== auth) . Just) newQueueBasicAuth
+                pure $ allowNewQueues && maybe True ((== auth_) . Just) newQueueBasicAuth
           SUB -> withQueue subscribeQueue
           GET -> withQueue getMessage
           ACK msgId -> withQueue $ acknowledgeMsg msgId
-          KEY sKey -> withQueue $ \q _ -> (corrId,entId,) <$> secureQueue_ q sKey
+          KEY sKey -> withQueue $ \q _ -> either err (corrId,entId,) <$> secureQueue_ q sKey
+          RKEY rKeys -> withQueue $ \q qr -> checkMode QMContact qr $ OK <$$ liftIO (updateKeys (queueStore ms) q rKeys)
+          LSET lnkId d ->
+            withQueue $ \q qr -> checkMode QMContact qr $ liftIO $ case queueData qr of
+              Just (lnkId', _) | lnkId' /= lnkId -> pure $ Left AUTH
+              _ -> OK <$$ addQueueLinkData (queueStore ms) q lnkId d
+          LDEL ->
+            withQueue $ \q qr -> checkMode QMContact qr $ liftIO $ case queueData qr of
+              Just _ -> OK <$$ deleteQueueLinkData (queueStore ms) q
+              Nothing -> pure $ Right OK
           NKEY nKey dhKey -> withQueue $ \q _ -> addQueueNotifier_ q nKey dhKey
           NDEL -> withQueue $ \q _ -> deleteQueueNotifier_ q
           OFF -> maybe (pure $ err INTERNAL) suspendQueue_ q_
           DEL -> maybe (pure $ err INTERNAL) delQueueAndMsgs q_
           QUE -> withQueue $ \q qr -> (corrId,entId,) <$> getQueueInfo q qr
       where
-        createQueue :: RcvPublicAuthKey -> RcvPublicDhKey -> SubscriptionMode -> SenderCanSecure -> M (Transmission BrokerMsg)
-        createQueue recipientKey dhKey subMode sndSecure = time "NEW" $ do
-          (rcvPublicDhKey, privDhKey) <- atomically . C.generateKeyPair =<< asks random
+        createQueue :: NewQueueReq -> M (Transmission BrokerMsg)
+        createQueue NewQueueReq {rcvAuthKey, rcvDhKey, subMode, queueReqData} = time "NEW" $ do
+          g <- asks random
+          idSize <- asks $ queueIdBytes . config
           updatedAt <- Just <$> liftIO getSystemDate
-          let rcvDhSecret = C.dh' dhKey privDhKey
-              qik (rcvId, sndId) = QIK {rcvId, sndId, rcvPublicDhKey, sndSecure}
-              qRec senderId =
-                QueueRec
-                  { senderId,
-                    recipientKey,
-                    rcvDhSecret,
-                    senderKey = Nothing,
-                    notifier = Nothing,
-                    status = EntityActive,
-                    sndSecure,
-                    updatedAt
-                  }
-          (corrId,entId,) <$> addQueueRetry 3 qik qRec
-          where
-            addQueueRetry ::
-              Int -> ((RecipientId, SenderId) -> QueueIdsKeys) -> (SenderId -> QueueRec) -> M BrokerMsg
-            addQueueRetry 0 _ _ = pure $ ERR INTERNAL
-            addQueueRetry n qik qRec = do
-              ids@(rId, sId) <- getIds
-              let qr = qRec sId
-              liftIO (addQueue ms rId qr) >>= \case
-                Left DUPLICATE_ -> addQueueRetry (n - 1) qik qRec
-                Left e -> pure $ ERR e
-                Right q -> do
-                  stats <- asks serverStats
-                  incStat $ qCreated stats
-                  incStat $ qCount stats
-                  case subMode of
-                    SMOnlyCreate -> pure ()
-                    SMSubscribe -> void $ subscribeQueue q qr
-                  pure $ IDS (qik ids)
-
-            getIds :: M (RecipientId, SenderId)
-            getIds = do
-              n <- asks $ queueIdBytes . config
-              liftM2 (,) (randomId n) (randomId n)
-
-        secureQueue_ :: StoreQueue s -> SndPublicAuthKey -> M BrokerMsg
+          (rcvPublicDhKey, privDhKey) <- atomically $ C.generateKeyPair g
+          -- TODO [notifications]
+          -- ntfKeys_ <- forM ntfCreds $ \(NewNtfCreds notifierKey dhKey) -> do
+          --   (ntfPubDhKey, ntfPrivDhKey) <- atomically $ C.generateKeyPair g
+          --   pure (notifierKey, C.dh' dhKey ntfPrivDhKey, ntfPubDhKey)
+          let randId = EntityId <$> atomically (C.randomBytes idSize g)
+              -- TODO [notifications] the remaining 24 bytes are reserver for notifier ID
+              sndId' = B.take 24 $ C.sha3_384 (bs corrId)
+              tryCreate 0 = pure $ ERR INTERNAL
+              tryCreate n = do
+                (sndId, clntIds, queueData) <- case queueReqData of
+                  Just (QRMessaging (Just (sId, d))) -> (\linkId -> (sId, True, Just (linkId, d))) <$> randId
+                  Just (QRContact (Just (linkId, (sId, d)))) -> pure (sId, True, Just (linkId, d))
+                  _ -> (,False,Nothing) <$> randId
+                -- The condition that client-provided sender ID must match hash of correlation ID
+                -- prevents "ID oracle" attack, when creating queue with supplied ID can be used to check
+                -- if queue with this ID still exists.
+                if clntIds && unEntityId sndId /= sndId'
+                  then pure $ ERR $ CMD PROHIBITED
+                  else do
+                    rcvId <- randId
+                    -- TODO [notifications]
+                    -- ntf <- forM ntfKeys_ $ \(notifierKey, rcvNtfDhSecret, rcvPubDhKey) -> do
+                    --   notifierId <- randId
+                    --   pure (NtfCreds {notifierId, notifierKey, rcvNtfDhSecret}, ServerNtfCreds notifierId rcvPubDhKey)
+                    let queueMode = queueReqMode <$> queueReqData
+                        qr =
+                          QueueRec
+                            { senderId = sndId,
+                              recipientKeys = [rcvAuthKey],
+                              rcvDhSecret = C.dh' rcvDhKey privDhKey,
+                              senderKey = Nothing,
+                              queueMode,
+                              queueData,
+                              -- TODO [notifications]
+                              notifier = Nothing, -- fst <$> ntf,
+                              status = EntityActive,
+                              updatedAt
+                            }
+                    liftIO (addQueue ms rcvId qr) >>= \case
+                      Left DUPLICATE_ -- TODO [short links] possibly, we somehow need to understand which IDs caused collision to retry if it's not client-supplied?
+                        | clntIds -> pure $ ERR AUTH -- no retry on collision if sender ID is client-supplied
+                        | otherwise -> tryCreate (n - 1)
+                      Left e -> pure $ ERR e
+                      Right q -> do
+                        stats <- asks serverStats
+                        incStat $ qCreated stats
+                        incStat $ qCount stats
+                        -- TODO [notifications]
+                        -- when (isJust ntf) $ incStat $ ntfCreated stats
+                        case subMode of
+                          SMOnlyCreate -> pure ()
+                          SMSubscribe -> void $ subscribeQueue q qr
+                        pure $ IDS QIK {rcvId, sndId, rcvPublicDhKey, queueMode, linkId = fst <$> queueData} -- , serverNtfCreds = snd <$> ntf
+          (corrId,entId,) <$> tryCreate (3 :: Int)
+
+        checkMode :: QueueMode -> QueueRec -> M (Either ErrorType BrokerMsg) -> M (Transmission BrokerMsg)
+        checkMode qm QueueRec {queueMode} a =
+          either err (corrId,entId,)
+            <$> if queueMode == Just qm then a else pure $ Left AUTH
+
+        secureQueue_ :: StoreQueue s -> SndPublicAuthKey -> M (Either ErrorType BrokerMsg)
         secureQueue_ q sKey = do
-          liftIO (secureQueue (queueStore ms) q sKey) >>= \case
-            Left e -> pure $ ERR e
-            Right () -> do
-              stats <- asks serverStats
-              incStat $ qSecured stats
-              pure OK
+          liftIO (secureQueue (queueStore ms) q sKey)
+            $>> (asks serverStats >>= incStat . qSecured) $> Right OK
+
+        getQueueLink_ :: StoreQueue s -> QueueRec -> M (Either ErrorType BrokerMsg)
+        getQueueLink_ q qr = liftIO $ LNK (senderId qr) <$$> getQueueLinkData (queueStore ms) q entId
 
         addQueueNotifier_ :: StoreQueue s -> NtfPublicAuthKey -> RcvNtfPublicDhKey -> M (Transmission BrokerMsg)
         addQueueNotifier_ q notifierKey dhKey = time "NKEY" $ do
@@ -1619,7 +1660,7 @@ client
               pure $ MsgNtf {ntfMsgId = msgId, ntfTs = msgTs, ntfNonce, ntfEncMeta = fromRight "" encNMsgMeta}
 
         processForwardedCommand :: EncFwdTransmission -> M BrokerMsg
-        processForwardedCommand (EncFwdTransmission s) = fmap (either ERR id) . runExceptT $ do
+        processForwardedCommand (EncFwdTransmission s) = fmap (either ERR RRES) . runExceptT $ do
           THAuthServer {serverPrivKey, sessSecret'} <- maybe (throwE $ transportErr TENoServerAuth) pure (thAuth thParams')
           sessSecret <- maybe (throwE $ transportErr TENoServerAuth) pure sessSecret'
           let proxyNonce = C.cbNonce $ bs corrId
@@ -1654,7 +1695,7 @@ client
               r3 = EncFwdResponse $ C.cbEncryptNoPad sessSecret (C.reverseNonce proxyNonce) (smpEncode fr)
           stats <- asks serverStats
           incStat $ pMsgFwdsRecv stats
-          pure $ RRES r3
+          pure r3
           where
             rejectOrVerify :: Maybe (THandleAuth 'TServer) -> SignedTransmission ErrorType Cmd -> M (Either (Transmission BrokerMsg) (Maybe (StoreQueue s, QueueRec), Transmission Cmd))
             rejectOrVerify clntThAuth (tAuth, authorized, (corrId', entId', cmdOrError)) =
@@ -1667,6 +1708,8 @@ client
                     allowed = case cmd' of
                       Cmd SSender SEND {} -> True
                       Cmd SSender (SKEY _) -> True
+                      Cmd SSenderLink (LKEY _) -> True
+                      Cmd SSenderLink LGET -> True
                       _ -> False
                     verified = \case
                       VRVerified q -> Right (q, (corrId', entId', cmd'))
@@ -1722,12 +1765,12 @@ client
 
         getQueueInfo :: StoreQueue s -> QueueRec -> M BrokerMsg
         getQueueInfo q QueueRec {senderKey, notifier} = do
-          fmap (either ERR id) $ liftIO $ runExceptT $ do
+          fmap (either ERR INFO) $ liftIO $ runExceptT $ do
             qiSub <- liftIO $ TM.lookupIO entId subscriptions >>= mapM mkQSub
             qiSize <- getQueueSize ms q
             qiMsg <- toMsgInfo <$$> tryPeekMsg ms q
             let info = QueueInfo {qiSnd = isJust senderKey, qiNtf = isJust notifier, qiSub, qiSize, qiMsg}
-            pure $ INFO info
+            pure info
           where
             mkQSub Sub {subThread, delivered} = do
               qSubThread <- case subThread of
@@ -1789,7 +1832,7 @@ exportMessages :: MsgStoreClass s => Bool -> s -> FilePath -> Bool -> IO ()
 exportMessages tty ms f drainMsgs = do
   logInfo $ "saving messages to file " <> T.pack f
   liftIO $ withFile f WriteMode $ \h ->
-    tryAny (unsafeWithAllMsgQueues tty ms $ saveQueueMsgs h) >>= \case
+    tryAny (unsafeWithAllMsgQueues tty True ms $ saveQueueMsgs h) >>= \case
       Right (Sum total) -> logInfo $ "messages saved: " <> tshow total
       Left e -> do
         logError $ "error exporting messages: " <> tshow e
@@ -1826,7 +1869,7 @@ processServerMessages StartOptions {skipWarnings} = do
               run processValidateQueue
         | otherwise = logWarn "skipping message expiration" $> Nothing
         where
-          run a = unsafeWithAllMsgQueues False ms a `catchAny` \_ -> exitFailure
+          run a = unsafeWithAllMsgQueues False False ms a `catchAny` \_ -> exitFailure
           processExpireQueue :: Int64 -> JournalQueue s -> IO MessageStats
           processExpireQueue old q = unsafeRunStore q "processExpireQueue" $ do
             mq <- getMsgQueue ms q False
diff --git a/src/Simplex/Messaging/Server/Main.hs b/src/Simplex/Messaging/Server/Main.hs
index 99d4bf0f08..b586fd0f99 100644
--- a/src/Simplex/Messaging/Server/Main.hs
+++ b/src/Simplex/Messaging/Server/Main.hs
@@ -210,7 +210,7 @@ smpServerCLI_ generateSite serveStaticFiles attachStaticFiles cfgPath logPath =
               let storeCfg = PostgresStoreCfg {dbOpts, dbStoreLogPath = Nothing, confirmMigrations = MCConsole, deletedTTL = iniDeletedTTL ini}
               ps <- newJournalMsgStore $ PQStoreCfg storeCfg
               sl <- openWriteStoreLog False storeLogFilePath
-              Sum qCnt <- foldQueueRecs True (postgresQueueStore ps) Nothing $ \(rId, qr) -> logCreateQueue sl rId qr $> Sum (1 :: Int)
+              Sum qCnt <- foldQueueRecs True True (postgresQueueStore ps) Nothing $ \(rId, qr) -> logCreateQueue sl rId qr $> Sum (1 :: Int)
               putStrLn $ "Export completed: " <> show qCnt <> " queues"
               putStrLn $ case readStoreType ini of
                 Right (ASType SQSPostgres SMSJournal) -> "store_queues set to `database`, update it to `memory` in INI file."
diff --git a/src/Simplex/Messaging/Server/MsgStore/Journal.hs b/src/Simplex/Messaging/Server/MsgStore/Journal.hs
index 0b3992af59..d28300a755 100644
--- a/src/Simplex/Messaging/Server/MsgStore/Journal.hs
+++ b/src/Simplex/Messaging/Server/MsgStore/Journal.hs
@@ -323,8 +323,16 @@ instance QueueStoreClass (JournalQueue s) (QStore s) where
   {-# INLINE addQueue_ #-}
   getQueue_ = withQS getQueue_
   {-# INLINE getQueue_ #-}
+  addQueueLinkData = withQS addQueueLinkData
+  {-# INLINE addQueueLinkData #-}
+  getQueueLinkData = withQS getQueueLinkData
+  {-# INLINE getQueueLinkData #-}
+  deleteQueueLinkData = withQS deleteQueueLinkData
+  {-# INLINE deleteQueueLinkData #-}
   secureQueue = withQS secureQueue
   {-# INLINE secureQueue #-}
+  updateKeys = withQS updateKeys
+  {-# INLINE updateKeys #-}
   addQueueNotifier = withQS addQueueNotifier
   {-# INLINE addQueueNotifier #-}
   deleteQueueNotifier = withQS deleteQueueNotifier
@@ -386,11 +394,11 @@ instance MsgStoreClass (JournalMsgStore s) where
 
   -- This function can only be used in server CLI commands or before server is started.
   -- It does not cache queues and is NOT concurrency safe.
-  unsafeWithAllMsgQueues :: Monoid a => Bool -> JournalMsgStore s -> (JournalQueue s -> IO a) -> IO a
-  unsafeWithAllMsgQueues tty ms action = case queueStore_ ms of
+  unsafeWithAllMsgQueues :: Monoid a => Bool -> Bool -> JournalMsgStore s -> (JournalQueue s -> IO a) -> IO a
+  unsafeWithAllMsgQueues tty withData ms action = case queueStore_ ms of
     MQStore st -> withLoadedQueues st run 
 #if defined(dbServerPostgres)
-    PQStore st -> foldQueueRecs tty st Nothing $ uncurry (mkQueue ms False) >=> run
+    PQStore st -> foldQueueRecs tty withData st Nothing $ uncurry (mkQueue ms False) >=> run
 #endif
     where
       run q = do
@@ -410,7 +418,7 @@ instance MsgStoreClass (JournalMsgStore s) where
 #if defined(dbServerPostgres)
     PQStore st -> do
       let JournalMsgStore {queueLocks, sharedLock} = ms
-      foldQueueRecs tty st (Just veryOld) $ \(rId, qr) -> do
+      foldQueueRecs tty False st (Just veryOld) $ \(rId, qr) -> do
         q <- mkQueue ms False rId qr
         withSharedWaitLock rId queueLocks sharedLock $ run $ tryStore' "deleteExpiredMsgs" rId $
           getLoadedQueue q >>= unStoreIO . expireQueueMsgs ms now old
diff --git a/src/Simplex/Messaging/Server/MsgStore/STM.hs b/src/Simplex/Messaging/Server/MsgStore/STM.hs
index 0ae592069b..afde3ff82a 100644
--- a/src/Simplex/Messaging/Server/MsgStore/STM.hs
+++ b/src/Simplex/Messaging/Server/MsgStore/STM.hs
@@ -81,7 +81,7 @@ instance MsgStoreClass STMMsgStore where
   {-# INLINE closeMsgStore #-}
   withActiveMsgQueues = withLoadedQueues . queueStore_
   {-# INLINE withActiveMsgQueues #-}
-  unsafeWithAllMsgQueues _ = withLoadedQueues . queueStore_
+  unsafeWithAllMsgQueues _ _ = withLoadedQueues . queueStore_
   {-# INLINE unsafeWithAllMsgQueues #-}
 
   expireOldMessages :: Bool -> STMMsgStore -> Int64 -> Int64 -> IO MessageStats
diff --git a/src/Simplex/Messaging/Server/MsgStore/Types.hs b/src/Simplex/Messaging/Server/MsgStore/Types.hs
index 93c61370d2..82778b5a4b 100644
--- a/src/Simplex/Messaging/Server/MsgStore/Types.hs
+++ b/src/Simplex/Messaging/Server/MsgStore/Types.hs
@@ -37,7 +37,8 @@ class (Monad (StoreMonad s), QueueStoreClass (StoreQueue s) (QueueStore s)) => M
   closeMsgStore :: s -> IO ()
   withActiveMsgQueues :: Monoid a => s -> (StoreQueue s -> IO a) -> IO a
   -- This function can only be used in server CLI commands or before server is started.
-  unsafeWithAllMsgQueues :: Monoid a => Bool -> s -> (StoreQueue s -> IO a) -> IO a
+  -- tty, withData, store
+  unsafeWithAllMsgQueues :: Monoid a => Bool -> Bool -> s -> (StoreQueue s -> IO a) -> IO a
   -- tty, store, now, ttl
   expireOldMessages :: Bool -> s -> Int64 -> Int64 -> IO MessageStats
   logQueueStates :: s -> IO ()
diff --git a/src/Simplex/Messaging/Server/QueueStore.hs b/src/Simplex/Messaging/Server/QueueStore.hs
index f4c2f108e5..e90359d1d5 100644
--- a/src/Simplex/Messaging/Server/QueueStore.hs
+++ b/src/Simplex/Messaging/Server/QueueStore.hs
@@ -13,6 +13,7 @@ module Simplex.Messaging.Server.QueueStore where
 import Control.Applicative ((<|>))
 import Data.Functor (($>))
 import Data.Int (Int64)
+import Data.List.NonEmpty (NonEmpty)
 import Data.Time.Clock.System (SystemTime (..), getSystemTime)
 import Simplex.Messaging.Encoding.String
 import Simplex.Messaging.Protocol
@@ -25,14 +26,15 @@ import Simplex.Messaging.Util (eitherToMaybe)
 #endif
 
 data QueueRec = QueueRec
-  { recipientKey :: !RcvPublicAuthKey,
-    rcvDhSecret :: !RcvDhSecret,
-    senderId :: !SenderId,
-    senderKey :: !(Maybe SndPublicAuthKey),
-    sndSecure :: !SenderCanSecure,
-    notifier :: !(Maybe NtfCreds),
-    status :: !ServerEntityStatus,
-    updatedAt :: !(Maybe RoundedSystemTime)
+  { recipientKeys :: NonEmpty RcvPublicAuthKey,
+    rcvDhSecret :: RcvDhSecret,
+    senderId :: SenderId,
+    senderKey :: Maybe SndPublicAuthKey,
+    queueMode :: Maybe QueueMode,
+    queueData :: Maybe (LinkId, QueueLinkData),
+    notifier :: Maybe NtfCreds,
+    status :: ServerEntityStatus,
+    updatedAt :: Maybe RoundedSystemTime
   }
   deriving (Show)
 
diff --git a/src/Simplex/Messaging/Server/QueueStore/Postgres.hs b/src/Simplex/Messaging/Server/QueueStore/Postgres.hs
index 83a25cb0eb..f500a3f42e 100644
--- a/src/Simplex/Messaging/Server/QueueStore/Postgres.hs
+++ b/src/Simplex/Messaging/Server/QueueStore/Postgres.hs
@@ -41,11 +41,12 @@ import Data.Either (fromRight)
 import Data.Functor (($>))
 import Data.Int (Int64)
 import Data.List (intersperse)
+import Data.List.NonEmpty (NonEmpty)
 import qualified Data.Map.Strict as M
-import Data.Maybe (catMaybes)
+import Data.Maybe (catMaybes, fromMaybe)
 import qualified Data.Text as T
 import Data.Time.Clock.System (SystemTime (..), getSystemTime)
-import Database.PostgreSQL.Simple (Binary (..), Only (..), Query, SqlError)
+import Database.PostgreSQL.Simple (Binary (..), Only (..), Query, SqlError, (:.) (..))
 import qualified Database.PostgreSQL.Simple as DB
 import qualified Database.PostgreSQL.Simple.Copy as DB
 import Database.PostgreSQL.Simple.FromField (FromField (..))
@@ -57,6 +58,9 @@ import Simplex.Messaging.Agent.Client (withLockMap)
 import Simplex.Messaging.Agent.Lock (Lock)
 import Simplex.Messaging.Agent.Store.Postgres (createDBStore, closeDBStore)
 import Simplex.Messaging.Agent.Store.Postgres.Common
+import Simplex.Messaging.Agent.Store.Postgres.DB (blobFieldDecoder)
+import qualified Simplex.Messaging.Crypto as C
+import Simplex.Messaging.Encoding
 import Simplex.Messaging.Protocol
 import Simplex.Messaging.Server.QueueStore
 import Simplex.Messaging.Server.QueueStore.Postgres.Config
@@ -66,14 +70,14 @@ import Simplex.Messaging.Server.QueueStore.Types
 import Simplex.Messaging.Server.StoreLog
 import Simplex.Messaging.TMap (TMap)
 import qualified Simplex.Messaging.TMap as TM
-import Simplex.Messaging.Util (firstRow, ifM, tshow, (<$$>))
+import Simplex.Messaging.Util (eitherToMaybe, firstRow, ifM, tshow, (<$$>))
 import System.Exit (exitFailure)
 import System.IO (IOMode (..), hFlush, stdout)
 import UnliftIO.STM
 
 #if !defined(dbPostgres)
-import Simplex.Messaging.Agent.Store.Postgres.DB (blobFieldDecoder)
-import qualified Simplex.Messaging.Crypto as C
+import Data.Text.Encoding (decodeLatin1, encodeUtf8)
+import Simplex.Messaging.Agent.Store.Postgres.DB (fromTextField_)
 import Simplex.Messaging.Encoding.String
 #endif
 
@@ -84,6 +88,7 @@ data PostgresQueueStore q = PostgresQueueStore
     queues :: TMap RecipientId q,
     -- this map only cashes the queues that were attempted to send messages to,
     senders :: TMap SenderId RecipientId,
+    links :: TMap LinkId RecipientId,
     -- this map only cashes the queues that were attempted to be subscribed to,
     notifiers :: TMap NotifierId RecipientId,
     notifierLocks :: TMap NotifierId Lock,
@@ -99,9 +104,10 @@ instance StoreQueueClass q => QueueStoreClass q (PostgresQueueStore q) where
     dbStoreLog <- mapM (openWriteStoreLog True) dbStoreLogPath
     queues <- TM.emptyIO
     senders <- TM.emptyIO
+    links <- TM.emptyIO
     notifiers <- TM.emptyIO
     notifierLocks <- TM.emptyIO
-    pure PostgresQueueStore {dbStore, dbStoreLog, queues, senders, notifiers, notifierLocks, deletedTTL}
+    pure PostgresQueueStore {dbStore, dbStoreLog, queues, senders, links, notifiers, notifierLocks, deletedTTL}
     where
       err e = do
         logError $ "STORE: newQueueStore, error opening PostgreSQL database, " <> tshow e
@@ -145,10 +151,12 @@ instance StoreQueueClass q => QueueStoreClass q (PostgresQueueStore q) where
           >>= bimapM handleDuplicate pure
       atomically $ TM.insert rId sq queues
       atomically $ TM.insert (senderId qr) rId senders
+      forM_ (notifier qr) $ \NtfCreds {notifierId = nId} -> atomically $ TM.insert nId rId notifiers
+      forM_ (queueData qr) $ \(lnkId, _) -> atomically $ TM.insert lnkId rId links
       withLog "addStoreQueue" st $ \s -> logCreateQueue s rId qr
       pure sq
     where
-      PostgresQueueStore {queues, senders} = st
+      PostgresQueueStore {queues, senders, links, notifiers} = st
       -- Not doing duplicate checks in maps as the probability of duplicates is very low.
       -- It needs to be reconsidered when IDs are supplied by the users.
       -- hasId = anyM [TM.memberIO rId queues, TM.memberIO senderId senders, hasNotifier]
@@ -158,24 +166,27 @@ instance StoreQueueClass q => QueueStoreClass q (PostgresQueueStore q) where
   getQueue_ st mkQ party qId = case party of
     SRecipient -> getRcvQueue qId
     SSender -> TM.lookupIO qId senders >>= maybe (mask loadSndQueue) getRcvQueue
+    SSenderLink -> TM.lookupIO qId links >>= maybe (mask loadLinkQueue) getRcvQueue
     -- loaded queue is deleted from notifiers map to reduce cache size after queue was subscribed to by ntf server
     SNotifier -> TM.lookupIO qId notifiers >>= maybe (mask loadNtfQueue) (getRcvQueue >=> (atomically (TM.delete qId notifiers) $>))
     where
-      PostgresQueueStore {queues, senders, notifiers} = st
+      PostgresQueueStore {queues, senders, links, notifiers} = st
       getRcvQueue rId = TM.lookupIO rId queues >>= maybe (mask loadRcvQueue) (pure . Right)
       loadRcvQueue = do
         (rId, qRec) <- loadQueue " WHERE recipient_id = ?"
         liftIO $ cacheQueue rId qRec $ \_ -> pure () -- recipient map already checked, not caching sender ref
-      loadSndQueue = do
-        (rId, qRec) <- loadQueue " WHERE sender_id = ?"
-        liftIO $
-          TM.lookupIO rId queues -- checking recipient map first
-            >>= maybe (cacheQueue rId qRec cacheSender) (atomically (cacheSender rId) $>)
+      loadSndQueue = loadSndQueue_ " WHERE sender_id = ?"
+      loadLinkQueue = loadSndQueue_ " WHERE link_id = ?"
       loadNtfQueue = do
         (rId, qRec) <- loadQueue " WHERE notifier_id = ?"
         liftIO $
           TM.lookupIO rId queues -- checking recipient map first, not creating lock in map, not caching queue
             >>= maybe (mkQ False rId qRec) pure
+      loadSndQueue_ condition = do
+        (rId, qRec) <- loadQueue condition
+        liftIO $
+          TM.lookupIO rId queues -- checking recipient map first
+            >>= maybe (cacheQueue rId qRec cacheSender) (atomically (cacheSender rId) $>)
       mask = E.uninterruptibleMask_ . runExceptT
       cacheSender rId = TM.insert qId rId senders
       loadQueue condition =
@@ -197,6 +208,43 @@ instance StoreQueueClass q => QueueStoreClass q (PostgresQueueStore q) where
               TM.insert rId sq queues
               pure sq
 
+  getQueueLinkData :: PostgresQueueStore q -> q -> LinkId -> IO (Either ErrorType QueueLinkData)
+  getQueueLinkData st sq lnkId = runExceptT $ do
+    qr <- ExceptT $ readQueueRecIO $ queueRec sq
+    case queueData qr of
+      Just (lnkId', _) | lnkId' == lnkId ->
+        withDB "getQueueLinkData" st $ \db -> firstRow id AUTH $
+          DB.query db "SELECT fixed_data, user_data FROM msg_queues WHERE link_id = ? AND deleted_at IS NULL" (Only lnkId)
+      _ -> throwE AUTH
+
+  addQueueLinkData :: PostgresQueueStore q -> q -> LinkId -> QueueLinkData -> IO (Either ErrorType ())
+  addQueueLinkData st sq lnkId d = 
+    withQueueRec sq "addQueueLinkData" $ \q -> case queueData q of
+      Nothing ->
+        addLink q $ \db -> DB.execute db qry (d :. (lnkId, rId))
+      Just (lnkId', _) | lnkId' == lnkId ->
+        addLink q $ \db -> DB.execute db (qry <> " AND (fixed_data IS NULL OR fixed_data = ?)") (d :. (lnkId, rId, fst d))
+      _ -> throwE AUTH
+    where
+      rId = recipientId sq
+      addLink q update = do
+        assertUpdated $ withDB' "addQueueLinkData" st update
+        atomically $ writeTVar (queueRec sq) $ Just q {queueData = Just (lnkId, d)}
+        withLog "addQueueLinkData" st $ \s -> logCreateLink s rId lnkId d
+      qry = "UPDATE msg_queues SET fixed_data = ?, user_data = ?, link_id = ? WHERE recipient_id = ? AND deleted_at IS NULL"
+
+  deleteQueueLinkData :: PostgresQueueStore q -> q -> IO (Either ErrorType ())
+  deleteQueueLinkData st sq =
+    withQueueRec sq "deleteQueueLinkData" $ \q -> case queueData q of
+      Just _ -> do
+        assertUpdated $ withDB' "deleteQueueLinkData" st $ \db ->
+          DB.execute db "UPDATE msg_queues SET link_id = NULL, fixed_data = NULL, user_data = NULL WHERE recipient_id = ? AND deleted_at IS NULL" (Only rId)
+        atomically $ writeTVar (queueRec sq) $ Just q {queueData = Nothing}
+        withLog "deleteQueueLinkData" st (`logDeleteLink` rId)
+      _ -> throwE AUTH
+    where
+      rId = recipientId sq
+
   secureQueue :: PostgresQueueStore q -> q -> SndPublicAuthKey -> IO (Either ErrorType ())
   secureQueue st sq sKey =
     withQueueRec sq "secureQueue" $ \q -> do
@@ -211,6 +259,16 @@ instance StoreQueueClass q => QueueStoreClass q (PostgresQueueStore q) where
         Just k | sKey /= k -> throwE AUTH
         _ -> pure ()
 
+  updateKeys :: PostgresQueueStore q -> q -> NonEmpty RcvPublicAuthKey -> IO (Either ErrorType ())
+  updateKeys st sq rKeys =
+    withQueueRec sq "updateKeys" $ \q -> do
+      assertUpdated $ withDB' "updateKeys" st $ \db ->
+        DB.execute db "UPDATE msg_queues SET recipient_keys = ? WHERE recipient_id = ? AND deleted_at IS NULL" (rKeys, rId)
+      atomically $ writeTVar (queueRec sq) $ Just q {recipientKeys = rKeys}
+      withLog "updateKeys" st $ \s -> logUpdateKeys s rId rKeys
+    where
+      rId = recipientId sq
+
   addQueueNotifier :: PostgresQueueStore q -> q -> NtfCreds -> IO (Either ErrorType (Maybe NotifierId))
   addQueueNotifier st sq ntfCreds@NtfCreds {notifierId = nId, notifierKey, rcvNtfDhSecret} =
     withQueueRec sq "addQueueNotifier" $ \q ->
@@ -316,7 +374,7 @@ batchInsertQueues tty queues toStore = do
   let st = dbStore toStore
   count <-
     withConnection st $ \db -> do
-      DB.copy_ db "COPY msg_queues (recipient_id, recipient_key, rcv_dh_secret, sender_id, sender_key, snd_secure, notifier_id, notifier_key, rcv_ntf_dh_secret, status, updated_at) FROM STDIN WITH (FORMAT CSV)"
+      DB.copy_ db "COPY msg_queues (recipient_id, recipient_keys, rcv_dh_secret, sender_id, sender_key, snd_secure, notifier_id, notifier_key, rcv_ntf_dh_secret, status, updated_at) FROM STDIN WITH (FORMAT CSV)"
       mapM_ (putQueue db) (zip [1..] qs)
       DB.putCopyEnd db
   Only qCnt : _ <- withConnection st (`DB.query_` "SELECT count(*) FROM msg_queues")
@@ -332,15 +390,15 @@ insertQueueQuery :: Query
 insertQueueQuery =
   [sql|
     INSERT INTO msg_queues
-      (recipient_id, recipient_key, rcv_dh_secret, sender_id, sender_key, snd_secure, notifier_id, notifier_key, rcv_ntf_dh_secret, status, updated_at)
-    VALUES (?,?,?,?,?,?,?,?,?,?,?)
+      (recipient_id, recipient_keys, rcv_dh_secret, sender_id, sender_key, queue_mode, notifier_id, notifier_key, rcv_ntf_dh_secret, status, updated_at, link_id, fixed_data, user_data)
+    VALUES (?,?,?,?,?,?,?,?,?,?,?,?,?,?)
   |]
 
-foldQueueRecs :: Monoid a => Bool -> PostgresQueueStore q -> Maybe Int64 -> ((RecipientId, QueueRec) -> IO a) -> IO a
-foldQueueRecs tty st skipOld_ f = do
+foldQueueRecs :: forall a q. Monoid a => Bool -> Bool -> PostgresQueueStore q -> Maybe Int64 -> ((RecipientId, QueueRec) -> IO a) -> IO a
+foldQueueRecs tty withData st skipOld_ f = do
   (n, r) <- withConnection (dbStore st) $ \db ->
-    foldRecs db (0 :: Int, mempty) $ \(i, acc) row -> do
-      r <- f $ rowToQueueRec row
+    foldRecs db (0 :: Int, mempty) $ \(i, acc) qr -> do
+      r <- f qr
       let !i' = i + 1
           !acc' = acc <> r
       when (tty && i' `mod` 100000 == 0) $ putStr (progress i' <> "\r") >> hFlush stdout
@@ -348,45 +406,69 @@ foldQueueRecs tty st skipOld_ f = do
   when tty $ putStrLn $ progress n
   pure r
   where
-    foldRecs db = case skipOld_ of
-      Nothing -> DB.fold_ db (queueRecQuery <> " WHERE deleted_at IS NULL")
-      Just old -> DB.fold db (queueRecQuery <> " WHERE deleted_at IS NULL AND updated_at > ?") (Only old)
+    foldRecs db acc f' = case skipOld_ of
+      Nothing
+        | withData -> DB.fold_ db (query <> " WHERE deleted_at IS NULL") acc $ \acc' -> f' acc' . rowToQueueRecWithData
+        | otherwise -> DB.fold_ db (query <> " WHERE deleted_at IS NULL") acc $ \acc' -> f' acc' . rowToQueueRec
+      Just old
+        | withData -> DB.fold db (query <> " WHERE deleted_at IS NULL AND updated_at > ?") (Only old) acc $ \acc' -> f' acc' . rowToQueueRecWithData
+        | otherwise -> DB.fold db (query <> " WHERE deleted_at IS NULL AND updated_at > ?") (Only old) acc $ \acc' -> f' acc' . rowToQueueRec
+    query = if withData then queueRecQueryWithData else queueRecQuery
     progress i = "Processed: " <> show i <> " records"
 
 queueRecQuery :: Query
 queueRecQuery =
   [sql|
-    SELECT recipient_id, recipient_key, rcv_dh_secret,
-      sender_id, sender_key, snd_secure,
+    SELECT recipient_id, recipient_keys, rcv_dh_secret,
+      sender_id, sender_key, queue_mode,
+      notifier_id, notifier_key, rcv_ntf_dh_secret,
+      status, updated_at,
+      link_id
+    FROM msg_queues
+  |]
+
+queueRecQueryWithData :: Query
+queueRecQueryWithData =
+  [sql|
+    SELECT recipient_id, recipient_keys, rcv_dh_secret,
+      sender_id, sender_key, queue_mode,
       notifier_id, notifier_key, rcv_ntf_dh_secret,
-      status, updated_at
+      status, updated_at,
+      link_id, fixed_data, user_data
     FROM msg_queues
   |]
 
-type QueueRecRow = (RecipientId, RcvPublicAuthKey, RcvDhSecret, SenderId, Maybe SndPublicAuthKey, SenderCanSecure, Maybe NotifierId, Maybe NtfPublicAuthKey, Maybe RcvNtfDhSecret, ServerEntityStatus, Maybe RoundedSystemTime)
+type QueueRecRow = (RecipientId, NonEmpty RcvPublicAuthKey, RcvDhSecret, SenderId, Maybe SndPublicAuthKey, Maybe QueueMode, Maybe NotifierId, Maybe NtfPublicAuthKey, Maybe RcvNtfDhSecret, ServerEntityStatus, Maybe RoundedSystemTime, Maybe LinkId)
 
-queueRecToRow :: (RecipientId, QueueRec) -> QueueRecRow
-queueRecToRow (rId, QueueRec {recipientKey, rcvDhSecret, senderId, senderKey, sndSecure, notifier = n, status, updatedAt}) =
-  (rId, recipientKey, rcvDhSecret, senderId, senderKey, sndSecure, notifierId <$> n, notifierKey <$> n, rcvNtfDhSecret <$> n, status, updatedAt)
+queueRecToRow :: (RecipientId, QueueRec) -> QueueRecRow :. (Maybe EncDataBytes, Maybe EncDataBytes)
+queueRecToRow (rId, QueueRec {recipientKeys, rcvDhSecret, senderId, senderKey, queueMode, queueData, notifier = n, status, updatedAt}) =
+  (rId, recipientKeys, rcvDhSecret, senderId, senderKey, queueMode, notifierId <$> n, notifierKey <$> n, rcvNtfDhSecret <$> n, status, updatedAt, linkId_)
+    :. (fst <$> queueData_, snd <$> queueData_)
+  where
+    (linkId_, queueData_) = queueDataColumns queueData
 
 queueRecToText :: (RecipientId, QueueRec) -> ByteString
-queueRecToText (rId, QueueRec {recipientKey, rcvDhSecret, senderId, senderKey, sndSecure, notifier = n, status, updatedAt}) =
+queueRecToText (rId, QueueRec {recipientKeys, rcvDhSecret, senderId, senderKey, queueMode, queueData, notifier = n, status, updatedAt}) =
   LB.toStrict $ BB.toLazyByteString $ mconcat tabFields <> BB.char7 '\n'
   where
     tabFields = BB.char7 ',' `intersperse` fields
     fields =
       [ renderField (toField rId),
-        renderField (toField recipientKey),
+        renderField (toField recipientKeys),
         renderField (toField rcvDhSecret),
         renderField (toField senderId),
         nullable senderKey,
-        renderField (toField sndSecure),
+        nullable queueMode,
         nullable (notifierId <$> n),
         nullable (notifierKey <$> n),
         nullable (rcvNtfDhSecret <$> n),
         BB.char7 '"' <> renderField (toField status) <> BB.char7 '"',
-        nullable updatedAt
+        nullable updatedAt,
+        nullable linkId_,
+        nullable (fst <$> queueData_),
+        nullable (snd <$> queueData_)
       ]
+    (linkId_, queueData_) = queueDataColumns queueData
     nullable :: ToField a => Maybe a -> Builder
     nullable = maybe mempty (renderField . toField)
     renderField :: Action -> Builder
@@ -397,10 +479,23 @@ queueRecToText (rId, QueueRec {recipientKey, rcvDhSecret, senderId, senderKey, s
       EscapeIdentifier s -> BB.byteString s -- Not used in COPY data
       Many as -> mconcat (map renderField as)
 
+queueDataColumns :: Maybe (LinkId, QueueLinkData) -> (Maybe LinkId, Maybe QueueLinkData)
+queueDataColumns = \case
+  Just (linkId, linkData) -> (Just linkId, Just linkData)
+  Nothing -> (Nothing, Nothing)
+
 rowToQueueRec :: QueueRecRow -> (RecipientId, QueueRec)
-rowToQueueRec (rId, recipientKey, rcvDhSecret, senderId, senderKey, sndSecure, notifierId_, notifierKey_, rcvNtfDhSecret_, status, updatedAt) =
+rowToQueueRec (rId, recipientKeys, rcvDhSecret, senderId, senderKey, queueMode, notifierId_, notifierKey_, rcvNtfDhSecret_, status, updatedAt, linkId_) =
   let notifier = NtfCreds <$> notifierId_ <*> notifierKey_ <*> rcvNtfDhSecret_
-   in (rId, QueueRec {recipientKey, rcvDhSecret, senderId, senderKey, sndSecure, notifier, status, updatedAt})
+      queueData = (,(EncDataBytes "", EncDataBytes "")) <$> linkId_
+   in (rId, QueueRec {recipientKeys, rcvDhSecret, senderId, senderKey, queueMode, queueData, notifier, status, updatedAt})
+
+rowToQueueRecWithData :: QueueRecRow :. (Maybe EncDataBytes, Maybe EncDataBytes) -> (RecipientId, QueueRec)
+rowToQueueRecWithData ((rId, recipientKeys, rcvDhSecret, senderId, senderKey, queueMode, notifierId_, notifierKey_, rcvNtfDhSecret_, status, updatedAt, linkId_) :. (immutableData_, userData_)) =
+  let notifier = NtfCreds <$> notifierId_ <*> notifierKey_ <*> rcvNtfDhSecret_
+      encData =  fromMaybe (EncDataBytes "")
+      queueData = (,(encData immutableData_, encData userData_)) <$> linkId_
+   in (rId, QueueRec {recipientKeys, rcvDhSecret, senderId, senderKey, queueMode, queueData, notifier, status, updatedAt})
 
 setStatusDB :: StoreQueueClass q => String -> PostgresQueueStore q -> q -> ServerEntityStatus -> ExceptT ErrorType IO () -> IO (Either ErrorType ())
 setStatusDB op st sq status writeLog =
@@ -445,7 +540,15 @@ instance ToField EntityId where toField (EntityId s) = toField $ Binary s
 
 deriving newtype instance FromField EntityId
 
+instance ToField (NonEmpty C.APublicAuthKey) where toField = toField . Binary . smpEncode
+
+instance FromField (NonEmpty C.APublicAuthKey) where fromField = blobFieldDecoder smpDecode
+
 #if !defined(dbPostgres)
+instance FromField QueueMode where fromField = fromTextField_ $ eitherToMaybe . smpDecode . encodeUtf8
+
+instance ToField QueueMode where toField = toField . decodeLatin1 . smpEncode
+
 instance ToField (C.DhSecret 'C.X25519) where toField = toField . Binary . C.dhBytes'
 
 instance FromField (C.DhSecret 'C.X25519) where fromField = blobFieldDecoder strDecode
@@ -453,4 +556,8 @@ instance FromField (C.DhSecret 'C.X25519) where fromField = blobFieldDecoder str
 instance ToField C.APublicAuthKey where toField = toField . Binary . C.encodePubKey
 
 instance FromField C.APublicAuthKey where fromField = blobFieldDecoder C.decodePubKey
+
+instance ToField EncDataBytes where toField (EncDataBytes s) = toField (Binary s)
+
+deriving newtype instance FromField EncDataBytes
 #endif
diff --git a/src/Simplex/Messaging/Server/QueueStore/Postgres/Migrations.hs b/src/Simplex/Messaging/Server/QueueStore/Postgres/Migrations.hs
index a5b69b94ba..b1c5501f6d 100644
--- a/src/Simplex/Messaging/Server/QueueStore/Postgres/Migrations.hs
+++ b/src/Simplex/Messaging/Server/QueueStore/Postgres/Migrations.hs
@@ -12,7 +12,8 @@ import Text.RawString.QQ (r)
 serverSchemaMigrations :: [(String, Text, Maybe Text)]
 serverSchemaMigrations =
   [ ("20250207_initial", m20250207_initial, Nothing),
-    ("20250319_updated_index", m20250319_updated_index, Just down_m20250319_updated_index)
+    ("20250319_updated_index", m20250319_updated_index, Just down_m20250319_updated_index),
+    ("20250320_short_links", m20250320_short_links, Just down_m20250320_short_links)
   ]
 
 -- | The list of migrations in ascending order by date
@@ -61,3 +62,60 @@ down_m20250319_updated_index =
 DROP INDEX idx_msg_queues_updated_at;
 CREATE INDEX idx_msg_queues_deleted_at ON msg_queues (deleted_at);
     |]
+
+m20250320_short_links :: Text
+m20250320_short_links =
+  T.pack
+    [r|
+ALTER TABLE msg_queues
+  ADD COLUMN queue_mode TEXT,
+  ADD COLUMN link_id BYTEA,
+  ADD COLUMN fixed_data BYTEA,
+  ADD COLUMN user_data BYTEA;
+
+UPDATE msg_queues SET queue_mode = 'M' WHERE snd_secure IS TRUE;
+
+ALTER TABLE msg_queues DROP COLUMN snd_secure;
+
+UPDATE msg_queues SET recipient_key = ('\x01'::BYTEA || chr(length(recipient_key))::BYTEA || recipient_key);
+
+ALTER TABLE msg_queues RENAME COLUMN recipient_key TO recipient_keys;
+
+CREATE UNIQUE INDEX idx_msg_queues_link_id ON msg_queues(link_id);
+    |]
+
+down_m20250320_short_links :: Text
+down_m20250320_short_links =
+  T.pack
+    [r|
+ALTER TABLE msg_queues ADD COLUMN snd_secure BOOLEAN NOT NULL DEFAULT FALSE;
+
+UPDATE msg_queues SET snd_secure = TRUE WHERE queue_mode = 'M';
+
+DROP INDEX idx_msg_queues_link_id;
+
+ALTER TABLE msg_queues
+  DROP COLUMN queue_mode,
+  DROP COLUMN link_id,
+  DROP COLUMN fixed_data,
+  DROP COLUMN user_data;
+
+DO $$
+  DECLARE bad_id BYTEA;
+  BEGIN
+    SELECT recipient_id INTO bad_id
+    FROM msg_queues
+    WHERE get_byte(recipient_keys, 0) != 1
+      OR get_byte(recipient_keys, 1) != length(recipient_keys) - 2
+    LIMIT 1;
+
+    IF bad_id IS NOT NULL
+    THEN RAISE EXCEPTION 'Cannot downgrade: many keys or incorrect length in recipient_keys for %', encode(bad_id, 'base64');
+    END IF;
+  END;
+$$;
+
+UPDATE msg_queues SET recipient_keys = substring(recipient_keys from 3);
+
+ALTER TABLE msg_queues RENAME COLUMN recipient_keys TO recipient_key;
+    |]
diff --git a/src/Simplex/Messaging/Server/QueueStore/Postgres/server_schema.sql b/src/Simplex/Messaging/Server/QueueStore/Postgres/server_schema.sql
new file mode 100644
index 0000000000..2910b6959d
--- /dev/null
+++ b/src/Simplex/Messaging/Server/QueueStore/Postgres/server_schema.sql
@@ -0,0 +1,74 @@
+
+
+SET statement_timeout = 0;
+SET lock_timeout = 0;
+SET idle_in_transaction_session_timeout = 0;
+SET client_encoding = 'UTF8';
+SET standard_conforming_strings = on;
+SELECT pg_catalog.set_config('search_path', '', false);
+SET check_function_bodies = false;
+SET xmloption = content;
+SET client_min_messages = warning;
+SET row_security = off;
+
+
+CREATE SCHEMA smp_server;
+
+
+SET default_table_access_method = heap;
+
+
+CREATE TABLE smp_server.migrations (
+    name text NOT NULL,
+    ts timestamp without time zone NOT NULL,
+    down text
+);
+
+
+
+CREATE TABLE smp_server.msg_queues (
+    recipient_id bytea NOT NULL,
+    recipient_keys bytea NOT NULL,
+    rcv_dh_secret bytea NOT NULL,
+    sender_id bytea NOT NULL,
+    sender_key bytea,
+    notifier_id bytea,
+    notifier_key bytea,
+    rcv_ntf_dh_secret bytea,
+    status text NOT NULL,
+    updated_at bigint,
+    deleted_at bigint,
+    queue_mode text,
+    link_id bytea,
+    fixed_data bytea,
+    user_data bytea
+);
+
+
+
+ALTER TABLE ONLY smp_server.migrations
+    ADD CONSTRAINT migrations_pkey PRIMARY KEY (name);
+
+
+
+ALTER TABLE ONLY smp_server.msg_queues
+    ADD CONSTRAINT msg_queues_pkey PRIMARY KEY (recipient_id);
+
+
+
+CREATE UNIQUE INDEX idx_msg_queues_link_id ON smp_server.msg_queues USING btree (link_id);
+
+
+
+CREATE UNIQUE INDEX idx_msg_queues_notifier_id ON smp_server.msg_queues USING btree (notifier_id);
+
+
+
+CREATE UNIQUE INDEX idx_msg_queues_sender_id ON smp_server.msg_queues USING btree (sender_id);
+
+
+
+CREATE INDEX idx_msg_queues_updated_at ON smp_server.msg_queues USING btree (deleted_at, updated_at);
+
+
+
diff --git a/src/Simplex/Messaging/Server/QueueStore/QueueInfo.hs b/src/Simplex/Messaging/Server/QueueStore/QueueInfo.hs
index b329a54ffb..9cebd8af72 100644
--- a/src/Simplex/Messaging/Server/QueueStore/QueueInfo.hs
+++ b/src/Simplex/Messaging/Server/QueueStore/QueueInfo.hs
@@ -1,3 +1,6 @@
+{-# LANGUAGE CPP #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE TemplateHaskell #-}
 
 module Simplex.Messaging.Server.QueueStore.QueueInfo where
@@ -7,10 +10,12 @@ import qualified Data.Aeson.TH as JQ
 import qualified Data.Attoparsec.ByteString.Char8 as A
 import qualified Data.ByteString.Lazy.Char8 as LB
 import Data.Text (Text)
+import Data.Text.Encoding (decodeLatin1, encodeUtf8)
 import Data.Time.Clock (UTCTime)
+import Simplex.Messaging.Agent.Store.DB (FromField (..), ToField (..), fromTextField_)
 import Simplex.Messaging.Encoding
 import Simplex.Messaging.Parsers (defaultJSON, dropPrefix, enumJSON)
-import Simplex.Messaging.Util ((<$?>))
+import Simplex.Messaging.Util (eitherToMaybe, (<$?>))
 
 data QueueInfo = QueueInfo
   { qiSnd :: Bool,
@@ -40,6 +45,22 @@ data MsgInfo = MsgInfo
 data MsgType = MTMessage | MTQuota
   deriving (Eq, Show)
 
+data QueueMode = QMMessaging | QMContact deriving (Eq, Show)
+
+instance Encoding QueueMode where
+  smpEncode = \case
+    QMMessaging -> "M"
+    QMContact -> "C"
+  smpP =
+    A.anyChar >>= \case
+      'M' -> pure QMMessaging
+      'C' -> pure QMContact
+      _ -> fail "bad QueueMode"
+
+instance FromField QueueMode where fromField = fromTextField_ $ eitherToMaybe . smpDecode . encodeUtf8
+
+instance ToField QueueMode where toField = toField . decodeLatin1 . smpEncode
+
 $(JQ.deriveJSON (enumJSON $ dropPrefix "Q") ''QSubThread)
 
 $(JQ.deriveJSON defaultJSON ''QSub)
diff --git a/src/Simplex/Messaging/Server/QueueStore/STM.hs b/src/Simplex/Messaging/Server/QueueStore/STM.hs
index e22597d0e3..61fa3af45e 100644
--- a/src/Simplex/Messaging/Server/QueueStore/STM.hs
+++ b/src/Simplex/Messaging/Server/QueueStore/STM.hs
@@ -28,6 +28,7 @@ import Control.Logger.Simple
 import Control.Monad
 import Data.Bitraversable (bimapM)
 import Data.Functor (($>))
+import Data.List.NonEmpty (NonEmpty)
 import qualified Data.Map.Strict as M
 import qualified Data.Text as T
 import Simplex.Messaging.Protocol
@@ -44,6 +45,7 @@ data STMQueueStore q = STMQueueStore
   { queues :: TMap RecipientId q,
     senders :: TMap SenderId RecipientId,
     notifiers :: TMap NotifierId RecipientId,
+    links :: TMap LinkId RecipientId,
     storeLog :: TVar (Maybe (StoreLog 'WriteMode))
   }
 
@@ -58,8 +60,9 @@ instance StoreQueueClass q => QueueStoreClass q (STMQueueStore q) where
     queues <- TM.emptyIO
     senders <- TM.emptyIO
     notifiers <- TM.emptyIO
+    links <- TM.emptyIO
     storeLog <- newTVarIO Nothing
-    pure STMQueueStore {queues, senders, notifiers, storeLog}
+    pure STMQueueStore {queues, senders, notifiers, links, storeLog}
 
   closeQueueStore :: STMQueueStore q -> IO ()
   closeQueueStore STMQueueStore {queues, senders, notifiers, storeLog} = do
@@ -80,17 +83,19 @@ instance StoreQueueClass q => QueueStoreClass q (STMQueueStore q) where
     pure QueueCounts {queueCount, notifierCount}
 
   addQueue_ :: STMQueueStore q -> (RecipientId -> QueueRec -> IO q) -> RecipientId -> QueueRec -> IO (Either ErrorType q)
-  addQueue_ st mkQ rId qr@QueueRec {senderId = sId, notifier} = do
+  addQueue_ st mkQ rId qr@QueueRec {senderId = sId, notifier, queueData} = do
     sq <- mkQ rId qr
     add sq $>> withLog "addStoreQueue" st (\s -> logCreateQueue s rId qr) $> Right sq
     where
-      STMQueueStore {queues, senders, notifiers} = st
+      STMQueueStore {queues, senders, notifiers, links} = st
       add q = atomically $ ifM hasId (pure $ Left DUPLICATE_) $ Right () <$ do
         TM.insert rId q queues
         TM.insert sId rId senders
         forM_ notifier $ \NtfCreds {notifierId} -> TM.insert notifierId rId notifiers
-      hasId = anyM [TM.member rId queues, TM.member sId senders, hasNotifier]
+        forM_ queueData $ \(lnkId, _) -> TM.insert lnkId rId links
+      hasId = anyM [TM.member rId queues, TM.member sId senders, hasNotifier, hasLink]
       hasNotifier = maybe (pure False) (\NtfCreds {notifierId} -> TM.member notifierId notifiers) notifier
+      hasLink = maybe (pure False) (\(lnkId, _) -> TM.member lnkId links) queueData
 
   getQueue_ :: DirectParty p => STMQueueStore q -> (Bool -> RecipientId -> QueueRec -> IO q) -> SParty p -> QueueId -> IO (Either ErrorType q)
   getQueue_ st _ party qId =
@@ -98,8 +103,52 @@ instance StoreQueueClass q => QueueStoreClass q (STMQueueStore q) where
       SRecipient -> TM.lookupIO qId queues
       SSender -> TM.lookupIO qId senders $>>= (`TM.lookupIO` queues)
       SNotifier -> TM.lookupIO qId notifiers $>>= (`TM.lookupIO` queues)
+      SSenderLink -> TM.lookupIO qId links $>>= (`TM.lookupIO` queues)
     where
-      STMQueueStore {queues, senders, notifiers} = st
+      STMQueueStore {queues, senders, notifiers, links} = st
+
+  getQueueLinkData :: STMQueueStore q -> q -> LinkId -> IO (Either ErrorType QueueLinkData)
+  getQueueLinkData _ q lnkId = atomically $ readQueueRec (queueRec q) $>>= pure . getData
+    where
+      getData qr = case queueData qr of
+        Just (lnkId', d) | lnkId' == lnkId -> Right d
+        _ -> Left AUTH
+
+  addQueueLinkData :: STMQueueStore q -> q -> LinkId -> QueueLinkData -> IO (Either ErrorType ())
+  addQueueLinkData st sq lnkId d =
+    atomically (readQueueRec qr $>>= add)
+      $>> withLog "addQueueLinkData" st (\s -> logCreateLink s rId lnkId d)
+    where
+      rId = recipientId sq
+      qr = queueRec sq
+      add q = case queueData q of
+        Nothing -> addLink
+        Just (lnkId', d') | lnkId' == lnkId && fst d' == fst d -> addLink
+        _ -> pure $ Left AUTH
+        where
+          addLink = do
+            let !q' = q {queueData = Just (lnkId, d)}
+            writeTVar qr $ Just q'
+            TM.insert lnkId rId $ links st
+            pure $ Right ()
+
+  deleteQueueLinkData :: STMQueueStore q -> q -> IO (Either ErrorType ())
+  deleteQueueLinkData st sq =
+    withQueueRec qr delete
+      $>> withLog "deleteQueueLinkData" st (`logDeleteLink` recipientId sq)
+    where
+      qr = queueRec sq
+      delete q = forM (queueData q) $ \(lnkId, _) -> do
+        TM.delete lnkId $ links st
+        writeTVar qr $ Just q {queueData = Nothing}
+
+  updateKeys :: STMQueueStore q -> q -> NonEmpty RcvPublicAuthKey -> IO (Either ErrorType ())
+  updateKeys st sq rKeys =
+    withQueueRec qr update
+      $>> withLog "updateKeys" st (\s -> logUpdateKeys s (recipientId sq) rKeys)
+    where
+      qr = queueRec sq
+      update q = writeTVar qr $ Just q {recipientKeys = rKeys}
 
   secureQueue :: STMQueueStore q -> q -> SndPublicAuthKey -> IO (Either ErrorType ())
   secureQueue st sq sKey =
diff --git a/src/Simplex/Messaging/Server/QueueStore/Types.hs b/src/Simplex/Messaging/Server/QueueStore/Types.hs
index e4ff517fc7..9a52a9df8d 100644
--- a/src/Simplex/Messaging/Server/QueueStore/Types.hs
+++ b/src/Simplex/Messaging/Server/QueueStore/Types.hs
@@ -10,6 +10,7 @@ module Simplex.Messaging.Server.QueueStore.Types where
 import Control.Concurrent.STM
 import Control.Monad
 import Data.Int (Int64)
+import Data.List.NonEmpty (NonEmpty)
 import Simplex.Messaging.Protocol
 import Simplex.Messaging.Server.QueueStore
 import Simplex.Messaging.TMap (TMap)
@@ -30,7 +31,11 @@ class StoreQueueClass q => QueueStoreClass q s where
   compactQueues :: s -> IO Int64
   addQueue_ :: s -> (RecipientId -> QueueRec -> IO q) -> RecipientId -> QueueRec -> IO (Either ErrorType q)
   getQueue_ :: DirectParty p => s -> (Bool -> RecipientId -> QueueRec -> IO q) -> SParty p -> QueueId -> IO (Either ErrorType q)
+  getQueueLinkData :: s -> q -> LinkId -> IO (Either ErrorType QueueLinkData)
+  addQueueLinkData :: s -> q -> LinkId -> QueueLinkData -> IO (Either ErrorType ())
+  deleteQueueLinkData :: s -> q -> IO (Either ErrorType ())
   secureQueue :: s -> q -> SndPublicAuthKey -> IO (Either ErrorType ())
+  updateKeys :: s -> q -> NonEmpty RcvPublicAuthKey -> IO (Either ErrorType ())
   addQueueNotifier :: s -> q -> NtfCreds -> IO (Either ErrorType (Maybe NotifierId))
   deleteQueueNotifier :: s -> q -> IO (Either ErrorType (Maybe NotifierId))
   suspendQueue :: s -> q -> IO (Either ErrorType ())
diff --git a/src/Simplex/Messaging/Server/StoreLog.hs b/src/Simplex/Messaging/Server/StoreLog.hs
index 1cc8ebd6ce..80a2b75aa2 100644
--- a/src/Simplex/Messaging/Server/StoreLog.hs
+++ b/src/Simplex/Messaging/Server/StoreLog.hs
@@ -18,7 +18,10 @@ module Simplex.Messaging.Server.StoreLog
     closeStoreLog,
     writeStoreLogRecord,
     logCreateQueue,
+    logCreateLink,
+    logDeleteLink,
     logSecureQueue,
+    logUpdateKeys,
     logAddNotifier,
     logSuspendQueue,
     logBlockQueue,
@@ -37,14 +40,17 @@ import qualified Control.Exception as E
 import Control.Logger.Simple
 import Control.Monad
 import qualified Data.Attoparsec.ByteString.Char8 as A
+import Data.ByteString.Char8 (ByteString)
 import qualified Data.ByteString.Char8 as B
 import Data.Functor (($>))
 import Data.List (sort, stripPrefix)
+import Data.List.NonEmpty (NonEmpty)
 import Data.Maybe (mapMaybe)
 import qualified Data.Text as T
 import Data.Time.Clock (UTCTime, addUTCTime, getCurrentTime, nominalDay)
 import Data.Time.Format.ISO8601 (iso8601Show, iso8601ParseM)
 import GHC.IO (catchAny)
+import Simplex.Messaging.Encoding
 import Simplex.Messaging.Encoding.String
 import Simplex.Messaging.Protocol
 -- import Simplex.Messaging.Server.MsgStore.Types
@@ -57,7 +63,10 @@ import System.FilePath (takeDirectory, takeFileName)
 
 data StoreLogRecord
   = CreateQueue RecipientId QueueRec
+  | CreateLink RecipientId LinkId QueueLinkData
+  | DeleteLink RecipientId
   | SecureQueue QueueId SndPublicAuthKey
+  | UpdateKeys RecipientId (NonEmpty RcvPublicAuthKey)
   | AddNotifier QueueId NtfCreds
   | SuspendQueue QueueId
   | BlockQueue QueueId BlockingInfo
@@ -69,7 +78,10 @@ data StoreLogRecord
 
 data SLRTag
   = CreateQueue_
+  | CreateLink_
+  | DeleteLink_
   | SecureQueue_
+  | UpdateKeys_
   | AddNotifier_
   | SuspendQueue_
   | BlockQueue_
@@ -79,40 +91,50 @@ data SLRTag
   | UpdateTime_
 
 instance StrEncoding QueueRec where
-  strEncode QueueRec {recipientKey, rcvDhSecret, senderId, senderKey, sndSecure, notifier, status, updatedAt} =
+  strEncode QueueRec {recipientKeys, rcvDhSecret, senderId, senderKey, queueMode, queueData, notifier, status, updatedAt} =
     B.unwords
-      [ "rk=" <> strEncode recipientKey,
+      [ "rk=" <> strEncode recipientKeys,
         "rdh=" <> strEncode rcvDhSecret,
         "sid=" <> strEncode senderId,
         "sk=" <> strEncode senderKey
       ]
-      <> sndSecureStr
-      <> maybe "" notifierStr notifier
-      <> maybe "" updatedAtStr updatedAt
+      <> maybe "" ((" queue_mode=" <>) . smpEncode) queueMode
+      <> opt " link_id=" (fst <$> queueData)
+      <> opt " queue_data=" (snd <$> queueData)
+      <> opt " notifier=" notifier
+      <> opt " updated_at=" updatedAt
       <> statusStr
     where
-      sndSecureStr = if sndSecure then " sndSecure=" <> strEncode sndSecure else ""
-      notifierStr ntfCreds = " notifier=" <> strEncode ntfCreds
-      updatedAtStr t = " updated_at=" <> strEncode t
+      opt :: StrEncoding a => ByteString -> Maybe a -> ByteString
+      opt param = maybe "" ((param <>) . strEncode)
       statusStr = case status of
         EntityActive -> ""
         _ -> " status=" <> strEncode status
 
   strP = do
-    recipientKey <- "rk=" *> strP_
+    recipientKeys <- "rk=" *> strP_
     rcvDhSecret <- "rdh=" *> strP_
     senderId <- "sid=" *> strP_
     senderKey <- "sk=" *> strP
-    sndSecure <- (" sndSecure=" *> strP) <|> pure False
+    queueMode <-
+      toQueueMode <$> (" sndSecure=" *> strP)
+        <|> Just <$> (" queue_mode=" *> smpP)
+        <|> pure Nothing -- unknown queue mode, we cannot imply that it is contact address
+    queueData <- optional $ (,) <$> (" link_id=" *> strP) <*> (" queue_data=" *> strP)
     notifier <- optional $ " notifier=" *> strP
     updatedAt <- optional $ " updated_at=" *> strP
     status <- (" status=" *> strP) <|> pure EntityActive
-    pure QueueRec {recipientKey, rcvDhSecret, senderId, senderKey, sndSecure, notifier, status, updatedAt}
+    pure QueueRec {recipientKeys, rcvDhSecret, senderId, senderKey, queueMode, queueData, notifier, status, updatedAt}
+    where
+      toQueueMode sndSecure = Just $ if sndSecure then QMMessaging else QMContact
 
 instance StrEncoding SLRTag where
   strEncode = \case
     CreateQueue_ -> "CREATE"
+    CreateLink_ -> "LINK"
+    DeleteLink_ -> "LDELETE"
     SecureQueue_ -> "SECURE"
+    UpdateKeys_ -> "KEYS"
     AddNotifier_ -> "NOTIFIER"
     SuspendQueue_ -> "SUSPEND"
     BlockQueue_ -> "BLOCK"
@@ -124,7 +146,10 @@ instance StrEncoding SLRTag where
   strP =
     A.choice
       [ "CREATE" $> CreateQueue_,
+        "LINK" $> CreateLink_,
+        "LDELETE" $> DeleteLink_,
         "SECURE" $> SecureQueue_,
+        "KEYS" $> UpdateKeys_,
         "NOTIFIER" $> AddNotifier_,
         "SUSPEND" $> SuspendQueue_,
         "BLOCK" $> BlockQueue_,
@@ -137,7 +162,10 @@ instance StrEncoding SLRTag where
 instance StrEncoding StoreLogRecord where
   strEncode = \case
     CreateQueue rId q -> B.unwords [strEncode CreateQueue_, "rid=" <> strEncode rId, strEncode q]
+    CreateLink rId lnkId d -> strEncode (CreateLink_, rId, lnkId, d)
+    DeleteLink rId -> strEncode (DeleteLink_, rId)
     SecureQueue rId sKey -> strEncode (SecureQueue_, rId, sKey)
+    UpdateKeys rId rKeys -> strEncode (UpdateKeys_, rId, rKeys)
     AddNotifier rId ntfCreds -> strEncode (AddNotifier_, rId, ntfCreds)
     SuspendQueue rId -> strEncode (SuspendQueue_, rId)
     BlockQueue rId info -> strEncode (BlockQueue_, rId, info)
@@ -149,7 +177,10 @@ instance StrEncoding StoreLogRecord where
   strP =
     strP_ >>= \case
       CreateQueue_ -> CreateQueue <$> ("rid=" *> strP_) <*> strP
+      CreateLink_ -> CreateLink <$> strP_ <*> strP_ <*> strP
+      DeleteLink_ -> DeleteLink <$> strP
       SecureQueue_ -> SecureQueue <$> strP_ <*> strP
+      UpdateKeys_ -> UpdateKeys <$> strP_ <*> strP
       AddNotifier_ -> AddNotifier <$> strP_ <*> strP
       SuspendQueue_ -> SuspendQueue <$> strP
       BlockQueue_ -> BlockQueue <$> strP_ <*> strP
@@ -189,9 +220,18 @@ writeStoreLogRecord (WriteStoreLog _ h) r = E.uninterruptibleMask_ $ do
 logCreateQueue :: StoreLog 'WriteMode -> RecipientId -> QueueRec -> IO ()
 logCreateQueue s rId q = writeStoreLogRecord s $ CreateQueue rId q
 
+logCreateLink :: StoreLog 'WriteMode -> RecipientId -> LinkId -> QueueLinkData -> IO ()
+logCreateLink s rId lnkId d = writeStoreLogRecord s $ CreateLink rId lnkId d
+
+logDeleteLink :: StoreLog 'WriteMode -> RecipientId -> IO ()
+logDeleteLink s = writeStoreLogRecord s . DeleteLink
+
 logSecureQueue :: StoreLog 'WriteMode -> QueueId -> SndPublicAuthKey -> IO ()
 logSecureQueue s qId sKey = writeStoreLogRecord s $ SecureQueue qId sKey
 
+logUpdateKeys :: StoreLog 'WriteMode -> QueueId -> NonEmpty RcvPublicAuthKey -> IO ()
+logUpdateKeys s rId rKeys = writeStoreLogRecord s $ UpdateKeys rId rKeys
+
 logAddNotifier :: StoreLog 'WriteMode -> QueueId -> NtfCreds -> IO ()
 logAddNotifier s qId ntfCreds = writeStoreLogRecord s $ AddNotifier qId ntfCreds
 
diff --git a/src/Simplex/Messaging/Server/StoreLog/ReadWrite.hs b/src/Simplex/Messaging/Server/StoreLog/ReadWrite.hs
index 77be7c97a2..bc576001ce 100644
--- a/src/Simplex/Messaging/Server/StoreLog/ReadWrite.hs
+++ b/src/Simplex/Messaging/Server/StoreLog/ReadWrite.hs
@@ -16,7 +16,7 @@ import qualified Data.ByteString.Char8 as B
 import qualified Data.Text as T
 import Data.Text.Encoding (decodeLatin1)
 import Simplex.Messaging.Encoding.String
-import Simplex.Messaging.Protocol
+import Simplex.Messaging.Protocol (ErrorType, RecipientId, SParty (..))
 import Simplex.Messaging.Server.QueueStore (QueueRec)
 import Simplex.Messaging.Server.QueueStore.Types
 import Simplex.Messaging.Server.StoreLog
@@ -42,7 +42,10 @@ readQueueStore tty mkQ f st = readLogLines tty f $ \_ -> processLine
         procLogRecord :: StoreLogRecord -> IO ()
         procLogRecord = \case
           CreateQueue rId qr -> addQueue_ st mkQ rId qr >>= qError rId "CreateQueue"
+          CreateLink rId lnkId d -> withQueue rId "CreateLink" $ \q -> addQueueLinkData st q lnkId d
+          DeleteLink rId -> withQueue rId "DeleteLink" $ \q -> deleteQueueLinkData st q
           SecureQueue qId sKey -> withQueue qId "SecureQueue" $ \q -> secureQueue st q sKey
+          UpdateKeys rId rKeys -> withQueue rId "UpdateKeys" $ \q -> updateKeys st q rKeys
           AddNotifier qId ntfCreds -> withQueue qId "AddNotifier" $ \q -> addQueueNotifier st q ntfCreds
           SuspendQueue qId -> withQueue qId "SuspendQueue" $ suspendQueue st
           BlockQueue qId info -> withQueue qId "BlockQueue" $ \q -> blockQueue st q info
diff --git a/src/Simplex/Messaging/Transport.hs b/src/Simplex/Messaging/Transport.hs
index 67cb83d016..e815d6f367 100644
--- a/src/Simplex/Messaging/Transport.hs
+++ b/src/Simplex/Messaging/Transport.hs
@@ -52,6 +52,7 @@ module Simplex.Messaging.Transport
     deletedEventSMPVersion,
     encryptedBlockSMPVersion,
     blockedEntitySMPVersion,
+    shortLinksSMPVersion,
     simplexMQVersion,
     smpBlockSize,
     TransportConfig (..),
@@ -147,6 +148,7 @@ smpBlockSize = 16384
 -- 11 - additional encryption of transport blocks with forward secrecy (10/06/2024)
 -- 12 - BLOCKED error for blocked queues (1/11/2025)
 -- 14 - proxyServer handshake property to disable transport encryption between server and proxy (1/19/2025)
+-- 15 - short links, with associated data passed in NEW of LSET command (3/30/2025)
 
 data SMPVersion
 
@@ -183,6 +185,9 @@ blockedEntitySMPVersion = VersionSMP 12
 proxyServerHandshakeSMPVersion :: VersionSMP
 proxyServerHandshakeSMPVersion = VersionSMP 14
 
+shortLinksSMPVersion :: VersionSMP
+shortLinksSMPVersion = VersionSMP 15
+
 minClientSMPRelayVersion :: VersionSMP
 minClientSMPRelayVersion = VersionSMP 6
 
@@ -190,13 +195,13 @@ minServerSMPRelayVersion :: VersionSMP
 minServerSMPRelayVersion = VersionSMP 6
 
 currentClientSMPRelayVersion :: VersionSMP
-currentClientSMPRelayVersion = VersionSMP 14
+currentClientSMPRelayVersion = VersionSMP 15
 
 legacyServerSMPRelayVersion :: VersionSMP
 legacyServerSMPRelayVersion = VersionSMP 6
 
 currentServerSMPRelayVersion :: VersionSMP
-currentServerSMPRelayVersion = VersionSMP 14
+currentServerSMPRelayVersion = VersionSMP 15
 
 -- Max SMP protocol version to be used in e2e encrypted
 -- connection between client and server, as defined by SMP proxy.
@@ -204,7 +209,7 @@ currentServerSMPRelayVersion = VersionSMP 14
 -- to prevent client version fingerprinting by the
 -- destination relays when clients upgrade at different times.
 proxiedSMPRelayVersion :: VersionSMP
-proxiedSMPRelayVersion = VersionSMP 14
+proxiedSMPRelayVersion = VersionSMP 15
 
 -- minimal supported protocol version is 6
 -- TODO remove code that supports sending commands without batching
diff --git a/tests/AgentTests.hs b/tests/AgentTests.hs
index a9a64e5c7f..0b261672a0 100644
--- a/tests/AgentTests.hs
+++ b/tests/AgentTests.hs
@@ -6,7 +6,7 @@
 {-# LANGUAGE RankNTypes #-}
 {-# LANGUAGE ScopedTypeVariables #-}
 
-module AgentTests (agentTests) where
+module AgentTests (agentCoreTests, agentTests) where
 
 import AgentTests.ConnectionRequestTests
 import AgentTests.DoubleRatchetTests (doubleRatchetTests)
@@ -14,6 +14,7 @@ import AgentTests.FunctionalAPITests (functionalAPITests)
 import AgentTests.MigrationTests (migrationTests)
 import AgentTests.NotificationTests (notificationTests)
 import AgentTests.ServerChoice (serverChoiceTests)
+import AgentTests.ShortLinkTests (shortLinkTests)
 import Simplex.Messaging.Server.Env.STM (AStoreType (..))
 import Simplex.Messaging.Transport (ATransport (..))
 import Test.Hspec
@@ -24,11 +25,15 @@ import Simplex.Messaging.Agent.Store.Postgres.Util (dropAllSchemasExceptSystem)
 import AgentTests.SQLiteTests (storeTests)
 #endif
 
-agentTests :: (ATransport, AStoreType) -> Spec
-agentTests ps = do
+agentCoreTests :: Spec
+agentCoreTests = do
   describe "Migration tests" migrationTests
   describe "Connection request" connectionRequestTests
   describe "Double ratchet tests" doubleRatchetTests
+  describe "Short link tests" shortLinkTests
+
+agentTests :: (ATransport, AStoreType) -> Spec
+agentTests ps = do
 #if defined(dbPostgres)
   after_ (dropAllSchemasExceptSystem testDBConnectInfo) $ do
 #else
diff --git a/tests/AgentTests/ConnectionRequestTests.hs b/tests/AgentTests/ConnectionRequestTests.hs
index 14f19efc39..1782d3ccd2 100644
--- a/tests/AgentTests/ConnectionRequestTests.hs
+++ b/tests/AgentTests/ConnectionRequestTests.hs
@@ -4,6 +4,8 @@
 {-# LANGUAGE OverloadedLists #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE PatternSynonyms #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE TypeApplications #-}
 {-# OPTIONS_GHC -Wno-orphans #-}
 {-# OPTIONS_GHC -fno-warn-ambiguous-fields #-}
 
@@ -12,6 +14,8 @@ module AgentTests.ConnectionRequestTests
     connReqData,
     queueAddr,
     testE2ERatchetParams12,
+    contactConnRequest,
+    invConnRequest,
   ) where
 
 import Data.ByteString (ByteString)
@@ -19,8 +23,9 @@ import Network.HTTP.Types (urlEncode)
 import Simplex.Messaging.Agent.Protocol
 import qualified Simplex.Messaging.Crypto as C
 import Simplex.Messaging.Crypto.Ratchet
+import Simplex.Messaging.Encoding
 import Simplex.Messaging.Encoding.String
-import Simplex.Messaging.Protocol (EntityId (..), ProtocolServer (..), currentSMPClientVersion, supportedSMPClientVRange, pattern VersionSMPC)
+import Simplex.Messaging.Protocol (EntityId (..), ProtocolServer (..), QueueMode (..), currentSMPClientVersion, supportedSMPClientVRange, pattern VersionSMPC)
 import Simplex.Messaging.ServiceScheme (ServiceScheme (..))
 import Simplex.Messaging.Version
 import Test.Hspec
@@ -37,11 +42,14 @@ queueAddr =
     { smpServer = srv,
       senderId = EntityId "\223\142z\251",
       dhPublicKey = testDhKey,
-      sndSecure = False
+      queueMode = Just QMMessaging
     }
 
-queueAddrSK :: SMPQueueAddress
-queueAddrSK = queueAddr {sndSecure = True}
+queueAddrNoQM :: SMPQueueAddress
+queueAddrNoQM = queueAddr {queueMode = Nothing}
+
+queueAddrContact :: SMPQueueAddress
+queueAddrContact = queueAddr {queueMode = Just QMContact}
 
 queueAddr1 :: SMPQueueAddress
 queueAddr1 = queueAddr {smpServer = srv1}
@@ -49,6 +57,9 @@ queueAddr1 = queueAddr {smpServer = srv1}
 queueAddrNoPort :: SMPQueueAddress
 queueAddrNoPort = queueAddr {smpServer = srv {port = ""}}
 
+queueAddrNoPortNoQM :: SMPQueueAddress
+queueAddrNoPortNoQM = queueAddrNoQM {smpServer = srv {port = ""}}
+
 queueAddrNoPort1 :: SMPQueueAddress
 queueAddrNoPort1 = queueAddr {smpServer = srv1 {port = ""}}
 
@@ -56,26 +67,32 @@ queueAddrNoPort1 = queueAddr {smpServer = srv1 {port = ""}}
 queue :: SMPQueueUri
 queue = SMPQueueUri supportedSMPClientVRange queueAddr
 
-queueSK :: SMPQueueUri
-queueSK = SMPQueueUri supportedSMPClientVRange queueAddrSK
+queueNoQM :: SMPQueueUri
+queueNoQM = SMPQueueUri supportedSMPClientVRange queueAddrNoQM
+
+queueContact :: SMPQueueUri
+queueContact = SMPQueueUri supportedSMPClientVRange queueAddrContact
 
 queueStr :: ByteString
-queueStr = "smp://1234-w==@smp.simplex.im:5223/3456-w==#/?v=1-3&dh=" <> url testDhKeyStr <> "&srv=jjbyvoemxysm7qxap7m5d5m35jzv5qq6gnlv7s4rsn7tdwwmuqciwpid.onion"
+queueStr = "smp://1234-w==@smp.simplex.im:5223/3456-w==#/?v=1-4&dh=" <> url testDhKeyStr <> "&q=m&k=s" <> "&srv=jjbyvoemxysm7qxap7m5d5m35jzv5qq6gnlv7s4rsn7tdwwmuqciwpid.onion"
+
+queueStrNoQM :: ByteString
+queueStrNoQM = "smp://1234-w==@smp.simplex.im:5223/3456-w==#/?v=1-4&dh=" <> url testDhKeyStr <> "&srv=jjbyvoemxysm7qxap7m5d5m35jzv5qq6gnlv7s4rsn7tdwwmuqciwpid.onion"
 
-queueStrSK :: ByteString
-queueStrSK = "smp://1234-w==@smp.simplex.im:5223/3456-w==#/?v=1-3&dh=" <> url testDhKeyStr <> "&k=s" <> "&srv=jjbyvoemxysm7qxap7m5d5m35jzv5qq6gnlv7s4rsn7tdwwmuqciwpid.onion"
+queueStrContact :: ByteString
+queueStrContact = "smp://1234-w==@smp.simplex.im:5223/3456-w==#/?v=1-4&dh=" <> url testDhKeyStr <> "&q=c" <> "&srv=jjbyvoemxysm7qxap7m5d5m35jzv5qq6gnlv7s4rsn7tdwwmuqciwpid.onion"
 
 queue1 :: SMPQueueUri
 queue1 = SMPQueueUri supportedSMPClientVRange queueAddr1
 
 queue1Str :: ByteString
-queue1Str = "smp://1234-w==@smp.simplex.im:5223/3456-w==#/?v=1-3&dh=" <> url testDhKeyStr
+queue1Str = "smp://1234-w==@smp.simplex.im:5223/3456-w==#/?v=1-4&dh=" <> url testDhKeyStr <> "&q=m&k=s"
 
 queueV1 :: SMPQueueUri
-queueV1 = SMPQueueUri (mkVersionRange (VersionSMPC 1) (VersionSMPC 1)) queueAddr
+queueV1 = SMPQueueUri (mkVersionRange (VersionSMPC 1) (VersionSMPC 1)) queueAddrNoQM
 
 queueV1NoPort :: SMPQueueUri
-queueV1NoPort = (queueV1 :: SMPQueueUri) {queueAddress = queueAddrNoPort}
+queueV1NoPort = (queueV1 :: SMPQueueUri) {queueAddress = queueAddrNoPortNoQM}
 
 -- version range 2-3 uses new encoding
 -- it is fixed/changed in v5.8.2.
@@ -83,10 +100,10 @@ queueNew :: SMPQueueUri
 queueNew = SMPQueueUri (mkVersionRange (VersionSMPC 2) currentSMPClientVersion) queueAddr
 
 queueNewStr :: ByteString
-queueNewStr = "smp://1234-w==@smp.simplex.im,jjbyvoemxysm7qxap7m5d5m35jzv5qq6gnlv7s4rsn7tdwwmuqciwpid.onion:5223/3456-w==#/?v=2-3&dh=" <> url testDhKeyStr
+queueNewStr = "smp://1234-w==@smp.simplex.im,jjbyvoemxysm7qxap7m5d5m35jzv5qq6gnlv7s4rsn7tdwwmuqciwpid.onion:5223/3456-w==#/?v=2-4&dh=" <> url testDhKeyStr <> "&q=m&k=s"
 
 queueNewStr' :: ByteString
-queueNewStr' = "smp://1234-w==@smp.simplex.im,jjbyvoemxysm7qxap7m5d5m35jzv5qq6gnlv7s4rsn7tdwwmuqciwpid.onion:5223/3456-w==#/?v=2-3&dh=" <> testDhKeyStr
+queueNewStr' = "smp://1234-w==@smp.simplex.im,jjbyvoemxysm7qxap7m5d5m35jzv5qq6gnlv7s4rsn7tdwwmuqciwpid.onion:5223/3456-w==#/?v=2-4&dh=" <> testDhKeyStr <> "&q=m&k=s"
 
 queueNewNoPort :: SMPQueueUri
 queueNewNoPort = (queueNew :: SMPQueueUri) {queueAddress = queueAddrNoPort}
@@ -95,7 +112,7 @@ queueNew1 :: SMPQueueUri
 queueNew1 = SMPQueueUri (mkVersionRange (VersionSMPC 2) currentSMPClientVersion) queueAddr1
 
 queueNew1Str :: ByteString
-queueNew1Str = "smp://1234-w==@smp.simplex.im:5223/3456-w==#/?v=2-3&dh=" <> url testDhKeyStr
+queueNew1Str = "smp://1234-w==@smp.simplex.im:5223/3456-w==#/?v=2-4&dh=" <> url testDhKeyStr <> "&q=m&k=s"
 
 queueNew1NoPort :: SMPQueueUri
 queueNew1NoPort = (queueNew1 :: SMPQueueUri) {queueAddress = queueAddrNoPort1}
@@ -115,8 +132,11 @@ connReqData =
       crClientData = Nothing
     }
 
-connReqDataSK :: ConnReqUriData
-connReqDataSK = connReqData {crSmpQueues = [queueSK]}
+connReqDataNoQM :: ConnReqUriData
+connReqDataNoQM = connReqData {crSmpQueues = [queueNoQM]}
+
+connReqDataContact :: ConnReqUriData
+connReqDataContact = connReqData {crSmpQueues = [queueContact]}
 
 connReqData1 :: ConnReqUriData
 connReqData1 = connReqData {crSmpQueues = [queue1]}
@@ -146,10 +166,16 @@ testE2ERatchetParams12 :: RcvE2ERatchetParamsUri 'C.X448
 testE2ERatchetParams12 = E2ERatchetParamsUri supportedE2EEncryptVRange testDhPubKey testDhPubKey Nothing
 
 connectionRequest :: AConnectionRequestUri
-connectionRequest = ACR SCMInvitation $ CRInvitationUri connReqData testE2ERatchetParams
+connectionRequest = ACR SCMInvitation invConnRequest
+
+invConnRequest :: ConnectionRequestUri 'CMInvitation
+invConnRequest = CRInvitationUri connReqData testE2ERatchetParams
 
-connectionRequestSK :: AConnectionRequestUri
-connectionRequestSK = ACR SCMInvitation $ CRInvitationUri connReqDataSK testE2ERatchetParams
+connectionRequestNoQM :: AConnectionRequestUri
+connectionRequestNoQM = ACR SCMInvitation $ CRInvitationUri connReqDataNoQM testE2ERatchetParams
+
+connectionRequestContact :: AConnectionRequestUri
+connectionRequestContact = ACR SCMContact $ CRContactUri connReqDataContact
 
 connectionRequestV1 :: AConnectionRequestUri
 connectionRequestV1 = ACR SCMInvitation $ CRInvitationUri connReqDataV1 testE2ERatchetParams
@@ -164,7 +190,10 @@ connectionRequestNew1 :: AConnectionRequestUri
 connectionRequestNew1 = ACR SCMInvitation $ CRInvitationUri connReqDataNew1 testE2ERatchetParams
 
 contactAddress :: AConnectionRequestUri
-contactAddress = ACR SCMContact $ CRContactUri connReqData
+contactAddress = ACR SCMContact $ contactConnRequest
+
+contactConnRequest :: ConnectionRequestUri 'CMContact
+contactConnRequest = CRContactUri connReqData
 
 contactAddressV2 :: AConnectionRequestUri
 contactAddressV2 = ACR SCMContact $ CRContactUri connReqDataV2
@@ -209,14 +238,15 @@ connectionRequestTests =
   describe "connection request parsing / serializing" $ do
     it "should serialize and parse SMP queue URIs" $ do
       queue #==# queueStr
-      queue #== ("smp://1234-w==@smp.simplex.im:5223/3456-w==#" <> testDhKeyStr <> "/?v=1-3&extra_param=abc&srv=jjbyvoemxysm7qxap7m5d5m35jzv5qq6gnlv7s4rsn7tdwwmuqciwpid.onion")
-      queueSK #==# queueStrSK
+      queue #== ("smp://1234-w==@smp.simplex.im:5223/3456-w==#" <> testDhKeyStr <> "/?v=1-4&extra_param=abc&srv=jjbyvoemxysm7qxap7m5d5m35jzv5qq6gnlv7s4rsn7tdwwmuqciwpid.onion&q=m&k=s")
+      queueNoQM #==# queueStrNoQM
+      queueContact #==# queueStrContact
       queue1 #==# queue1Str
       queueNew #==# queueNewStr
       queueNew #== queueNewStr'
       queueNew1 #==# queueNew1Str
-      queueNewNoPort #==# ("smp://1234-w==@smp.simplex.im,jjbyvoemxysm7qxap7m5d5m35jzv5qq6gnlv7s4rsn7tdwwmuqciwpid.onion/3456-w==#/?v=2-3&dh=" <> url testDhKeyStr)
-      queueNew1NoPort #==# ("smp://1234-w==@smp.simplex.im/3456-w==#/?v=2-3&dh=" <> url testDhKeyStr)
+      queueNewNoPort #==# ("smp://1234-w==@smp.simplex.im,jjbyvoemxysm7qxap7m5d5m35jzv5qq6gnlv7s4rsn7tdwwmuqciwpid.onion/3456-w==#/?v=2-4&dh=" <> url testDhKeyStr <> "&q=m&k=s")
+      queueNew1NoPort #==# ("smp://1234-w==@smp.simplex.im/3456-w==#/?v=2-4&dh=" <> url testDhKeyStr <> "&q=m&k=s")
       queueV1 #==# ("smp://1234-w==@smp.simplex.im:5223/3456-w==#/?v=1&dh=" <> url testDhKeyStr <> "&srv=jjbyvoemxysm7qxap7m5d5m35jzv5qq6gnlv7s4rsn7tdwwmuqciwpid.onion")
       queueV1 #== ("smp://1234-w==@smp.simplex.im,jjbyvoemxysm7qxap7m5d5m35jzv5qq6gnlv7s4rsn7tdwwmuqciwpid.onion:5223/3456-w==#" <> testDhKeyStr)
       queueV1 #== ("smp://1234-w==@smp.simplex.im:5223/3456-w==#/?extra_param=abc&v=1&dh=" <> testDhKeyStr <> "&srv=jjbyvoemxysm7qxap7m5d5m35jzv5qq6gnlv7s4rsn7tdwwmuqciwpid.onion")
@@ -227,7 +257,7 @@ connectionRequestTests =
     it "should serialize and parse connection invitations and contact addresses" $ do
       connectionRequest #==# ("simplex:/invitation#/?v=2-7&smp=" <> url queueStr <> "&e2e=" <> testE2ERatchetParamsStrUri)
       connectionRequest #== ("https://simplex.chat/invitation#/?v=2-7&smp=" <> url queueStr <> "&e2e=" <> testE2ERatchetParamsStrUri)
-      connectionRequestSK #==# ("simplex:/invitation#/?v=2-7&smp=" <> url queueStrSK <> "&e2e=" <> testE2ERatchetParamsStrUri)
+      connectionRequestNoQM #==# ("simplex:/invitation#/?v=2-7&smp=" <> url queueStrNoQM <> "&e2e=" <> testE2ERatchetParamsStrUri)
       connectionRequest1 #==# ("simplex:/invitation#/?v=2-7&smp=" <> url queue1Str <> "&e2e=" <> testE2ERatchetParamsStrUri)
       connectionRequest2queues #==# ("simplex:/invitation#/?v=2-7&smp=" <> url (queueStr <> ";" <> queueStr) <> "&e2e=" <> testE2ERatchetParamsStrUri)
       connectionRequestNew #==# ("simplex:/invitation#/?v=2-7&smp=" <> url queueNewStr <> "&e2e=" <> testE2ERatchetParamsStrUri)
@@ -245,3 +275,82 @@ connectionRequestTests =
       contactAddressV2 #== ("https://simplex.chat/contact#/?v=1-2&smp=" <> url queueStr) -- adjusted to v2
       contactAddressV2 #== ("https://simplex.chat/contact#/?v=2-2&smp=" <> url queueStr)
       contactAddressClientData #==# ("simplex:/contact#/?v=2-7&smp=" <> url queueStr <> "&data=" <> url "{\"type\":\"group_link\", \"group_link_id\":\"abc\"}")
+    it "should serialize / parse queue address, connection invitations and contact addresses as binary" $ do
+      smpEncodingTest queue
+      smpEncodingTest queueNoQM -- this passes, no queue mode patch in SMPQueueUri encoding
+      -- smpEncodingTest queueContact -- this fails until SMP client min version is >= sndAuthKeySMPClientVersion
+      smpEncodingTest queue1
+      smpEncodingTest queueNew
+      smpEncodingTest queueNew1
+      smpEncodingTest queueNewNoPort
+      smpEncodingTest queueNew1NoPort
+      smpEncodingTest queueV1
+      smpEncodingTest queueV1NoPort
+      smpEncodingTest connectionRequest
+      -- smpEncodingTest connectionRequestNoQM -- this fails, because of queue mode patch
+      smpEncodingTest connectionRequestContact  -- this passes because of queue mode patch in ConnReqUriData encoding
+      smpEncodingTest connectionRequest1
+      smpEncodingTest connectionRequest2queues
+      smpEncodingTest connectionRequestNew
+      smpEncodingTest connectionRequestNew1
+      smpEncodingTest connectionRequest2queuesNew
+      smpEncodingTest connectionRequestClientDataEmpty
+      smpEncodingTest contactAddress
+      smpEncodingTest contactAddress2queues
+      smpEncodingTest contactAddressNew
+      smpEncodingTest contactAddress2queuesNew
+      smpEncodingTest contactAddressV2
+      smpEncodingTest contactAddressClientData
+    it "should serialize / parse short links" $ do
+      CSLContact SLSServer CCTContact srv (LinkKey "0123456789abcdef0123456789abcdef") #==# "https://smp.simplex.im/a#MDEyMzQ1Njc4OWFiY2RlZjAxMjM0NTY3ODlhYmNkZWY?h=jjbyvoemxysm7qxap7m5d5m35jzv5qq6gnlv7s4rsn7tdwwmuqciwpid.onion&p=5223&c=1234-w"
+      CSLContact SLSServer CCTGroup srv (LinkKey "0123456789abcdef0123456789abcdef") #==# "https://smp.simplex.im/g#MDEyMzQ1Njc4OWFiY2RlZjAxMjM0NTY3ODlhYmNkZWY?h=jjbyvoemxysm7qxap7m5d5m35jzv5qq6gnlv7s4rsn7tdwwmuqciwpid.onion&p=5223&c=1234-w"
+      CSLContact SLSServer CCTContact shortSrv (LinkKey "0123456789abcdef0123456789abcdef") #==# "https://smp.simplex.im/a#MDEyMzQ1Njc4OWFiY2RlZjAxMjM0NTY3ODlhYmNkZWY"
+      CSLInvitation SLSServer srv (EntityId "0123456789abcdef01234567") (LinkKey "0123456789abcdef0123456789abcdef") #==# "https://smp.simplex.im/i#MDEyMzQ1Njc4OWFiY2RlZjAxMjM0NTY3/MDEyMzQ1Njc4OWFiY2RlZjAxMjM0NTY3ODlhYmNkZWY?h=jjbyvoemxysm7qxap7m5d5m35jzv5qq6gnlv7s4rsn7tdwwmuqciwpid.onion&p=5223&c=1234-w"
+      CSLInvitation SLSServer shortSrv (EntityId "0123456789abcdef01234567") (LinkKey "0123456789abcdef0123456789abcdef") #==# "https://smp.simplex.im/i#MDEyMzQ1Njc4OWFiY2RlZjAxMjM0NTY3/MDEyMzQ1Njc4OWFiY2RlZjAxMjM0NTY3ODlhYmNkZWY"
+      CSLContact SLSSimplex CCTContact srv (LinkKey "0123456789abcdef0123456789abcdef") #==# "simplex:/a#MDEyMzQ1Njc4OWFiY2RlZjAxMjM0NTY3ODlhYmNkZWY?h=smp.simplex.im%2Cjjbyvoemxysm7qxap7m5d5m35jzv5qq6gnlv7s4rsn7tdwwmuqciwpid.onion&p=5223&c=1234-w"
+      CSLContact SLSSimplex CCTGroup srv (LinkKey "0123456789abcdef0123456789abcdef") #==# "simplex:/g#MDEyMzQ1Njc4OWFiY2RlZjAxMjM0NTY3ODlhYmNkZWY?h=smp.simplex.im%2Cjjbyvoemxysm7qxap7m5d5m35jzv5qq6gnlv7s4rsn7tdwwmuqciwpid.onion&p=5223&c=1234-w"
+      CSLContact SLSSimplex CCTContact shortSrv (LinkKey "0123456789abcdef0123456789abcdef") #==# "simplex:/a#MDEyMzQ1Njc4OWFiY2RlZjAxMjM0NTY3ODlhYmNkZWY?h=smp.simplex.im"
+      CSLInvitation SLSSimplex srv (EntityId "0123456789abcdef01234567") (LinkKey "0123456789abcdef0123456789abcdef") #==# "simplex:/i#MDEyMzQ1Njc4OWFiY2RlZjAxMjM0NTY3/MDEyMzQ1Njc4OWFiY2RlZjAxMjM0NTY3ODlhYmNkZWY?h=smp.simplex.im%2Cjjbyvoemxysm7qxap7m5d5m35jzv5qq6gnlv7s4rsn7tdwwmuqciwpid.onion&p=5223&c=1234-w"
+      CSLInvitation SLSSimplex shortSrv (EntityId "0123456789abcdef01234567") (LinkKey "0123456789abcdef0123456789abcdef") #==# "simplex:/i#MDEyMzQ1Njc4OWFiY2RlZjAxMjM0NTY3/MDEyMzQ1Njc4OWFiY2RlZjAxMjM0NTY3ODlhYmNkZWY?h=smp.simplex.im"
+    it "should shorten / restore short links" $ do
+      let contact = CSLContact SLSServer CCTContact
+      shortenShortLink [srv] (contact srv (LinkKey "0123456789abcdef0123456789abcdef"))
+        `shouldBe` contact shortSrv (LinkKey "0123456789abcdef0123456789abcdef")
+      -- won't shorten link that uses only onion host from preset server
+      shortenShortLink [srv] (contact srvOnion (LinkKey "0123456789abcdef0123456789abcdef"))
+        `shouldBe` contact srvOnion (LinkKey "0123456789abcdef0123456789abcdef")
+      -- will shorten link that uses only public host from preset server
+      shortenShortLink [srv] (contact srv1 (LinkKey "0123456789abcdef0123456789abcdef"))
+        `shouldBe` contact shortSrv (LinkKey "0123456789abcdef0123456789abcdef")
+      shortenShortLink [srv] (contact srv2 (LinkKey "0123456789abcdef0123456789abcdef"))
+        `shouldBe` contact srv2 (LinkKey "0123456789abcdef0123456789abcdef")
+      restoreShortLink [srv] (contact shortSrv (LinkKey "0123456789abcdef0123456789abcdef"))
+        `shouldBe` contact srv (LinkKey "0123456789abcdef0123456789abcdef")
+      -- won't change link that has only public host of preset server with keyhash
+      restoreShortLink [srv] (contact srv1 (LinkKey "0123456789abcdef0123456789abcdef"))
+        `shouldBe` contact srv1 (LinkKey "0123456789abcdef0123456789abcdef")
+      restoreShortLink [srv2] (contact shortSrv (LinkKey "0123456789abcdef0123456789abcdef"))
+        `shouldBe` contact shortSrv (LinkKey "0123456789abcdef0123456789abcdef")
+      restoreShortLink [srv] (contact srv2 (LinkKey "0123456789abcdef0123456789abcdef"))
+        `shouldBe` contact srv2 (LinkKey "0123456789abcdef0123456789abcdef")
+      Right (lnk :: ConnShortLink 'CMContact) <- pure $ strDecode "https://localhost/a#4AkRDmhf64tdRlN406g8lJRg5OCmhD6ynIhi6glOcCM?p=7001&c=LcJUMfVhwD8yxjAiSaDzzGF3-kLG4Uh0Fl_ZIjrRwjI"
+      Right (lnk' :: ConnShortLink 'CMContact) <- pure $ strDecode  "https://localhost/a#4AkRDmhf64tdRlN406g8lJRg5OCmhD6ynIhi6glOcCM"
+      let presetSrv :: SMPServer = "smp://LcJUMfVhwD8yxjAiSaDzzGF3-kLG4Uh0Fl_ZIjrRwjI=@localhost:7001"
+      shortenShortLink [presetSrv] lnk `shouldBe` lnk'
+      restoreShortLink [presetSrv] lnk' `shouldBe` lnk
+      Right (inv :: ConnShortLink 'CMInvitation) <- pure $ strDecode "https://localhost/i#tnUaHYp8saREmyEHR93SBpl8ySHBchOt/LJ1ZQUzxH9Udb0jw5wmJACv5o6oe8e7BsX_hUCUMTSY?p=7001&c=LcJUMfVhwD8yxjAiSaDzzGF3-kLG4Uh0Fl_ZIjrRwjI"
+      Right (inv' :: ConnShortLink 'CMInvitation) <- pure $ strDecode  "https://localhost/i#tnUaHYp8saREmyEHR93SBpl8ySHBchOt/LJ1ZQUzxH9Udb0jw5wmJACv5o6oe8e7BsX_hUCUMTSY"
+      shortenShortLink [presetSrv] inv `shouldBe` inv'
+      restoreShortLink [presetSrv] inv' `shouldBe` inv
+  where
+    smpEncodingTest :: (Encoding a, Eq a, Show a, HasCallStack) => a -> Expectation
+    smpEncodingTest a = smpDecode (smpEncode a) `shouldBe` Right a
+
+shortSrv :: SMPServer
+shortSrv = SMPServer "smp.simplex.im" "" (C.KeyHash "")
+
+srvOnion :: SMPServer
+srvOnion = SMPServer "jjbyvoemxysm7qxap7m5d5m35jzv5qq6gnlv7s4rsn7tdwwmuqciwpid.onion" "" (C.KeyHash "\215m\248\251")
+
+srv2 :: SMPServer
+srv2 = SMPServer "smp2.simplex.im,jjbyvoemxysm7qxap7m5d5m35jzv5qq6gnlv7s4rsn7tdwwmuqciwpid.onion" "" (C.KeyHash "\215m\248\251")
diff --git a/tests/AgentTests/EqInstances.hs b/tests/AgentTests/EqInstances.hs
index a810247fea..5b05444fc1 100644
--- a/tests/AgentTests/EqInstances.hs
+++ b/tests/AgentTests/EqInstances.hs
@@ -5,6 +5,7 @@
 module AgentTests.EqInstances where
 
 import Data.Type.Equality
+import Simplex.Messaging.Agent.Protocol (ConnLinkData (..), OwnerAuth (..))
 import Simplex.Messaging.Agent.Store
 import Simplex.Messaging.Client (ProxiedRelay (..))
 
@@ -25,6 +26,16 @@ deriving instance Eq (DBQueueId q)
 
 deriving instance Eq ClientNtfCreds
 
+deriving instance Eq ShortLinkCreds
+
+deriving instance Show (ConnLinkData c)
+
+deriving instance Eq (ConnLinkData c)
+
+deriving instance Show OwnerAuth
+
+deriving instance Eq OwnerAuth
+
 deriving instance Show ProxiedRelay
 
 deriving instance Eq ProxiedRelay
diff --git a/tests/AgentTests/FunctionalAPITests.hs b/tests/AgentTests/FunctionalAPITests.hs
index cbe1c47bcd..c49703d1c3 100644
--- a/tests/AgentTests/FunctionalAPITests.hs
+++ b/tests/AgentTests/FunctionalAPITests.hs
@@ -55,6 +55,7 @@ module AgentTests.FunctionalAPITests
 where
 
 import AgentTests.ConnectionRequestTests (connReqData, queueAddr, testE2ERatchetParams12)
+import AgentTests.EqInstances ()
 import Control.Concurrent (forkIO, killThread, threadDelay)
 import Control.Monad
 import Control.Monad.Except
@@ -77,7 +78,7 @@ import Data.Type.Equality (testEquality, (:~:) (Refl))
 import Data.Word (Word16)
 import GHC.Stack (withFrozenCallStack)
 import SMPAgentClient
-import SMPClient (cfgMS, cfgJ2QS, prevRange, prevVersion, testPort, testPort2, testStoreLogFile, withSmpServer, withSmpServerConfigOn, withSmpServerProxy, withSmpServerStoreLogOn, withSmpServerStoreMsgLogOn)
+import SMPClient (cfgJ2QS, cfgMS, prevRange, prevVersion, proxyCfgJ2QS, proxyCfgMS, testPort, testPort2, testStoreLogFile, withSmpServer, withSmpServers2, withSmpServerConfigOn, withSmpServerProxy, withSmpServersProxy2, withSmpServerStoreLogOn, withSmpServerStoreMsgLogOn)
 import Simplex.Messaging.Agent hiding (createConnection, joinConnection, sendMessage)
 import qualified Simplex.Messaging.Agent as A
 import Simplex.Messaging.Agent.Client (ProtocolTestFailure (..), ProtocolTestStep (..), ServerQueueInfo (..), UserNetworkInfo (..), UserNetworkType (..), waitForUserNetwork)
@@ -88,19 +89,20 @@ import Simplex.Messaging.Agent.Store.Common (DBStore (..), withTransaction)
 import Simplex.Messaging.Agent.Store.Interface
 import qualified Simplex.Messaging.Agent.Store.DB as DB
 import Simplex.Messaging.Agent.Store.Shared (MigrationConfirmation (..), MigrationError (..))
-import Simplex.Messaging.Client (NetworkConfig (..), ProtocolClientConfig (..), SMPProxyFallback (..), SMPProxyMode (..), TransportSessionMode (..), defaultClientConfig)
+import Simplex.Messaging.Client (NetworkConfig (..), ProtocolClientConfig (..), TransportSessionMode (..), defaultClientConfig)
 import qualified Simplex.Messaging.Crypto as C
 import Simplex.Messaging.Crypto.Ratchet (InitialKeys (..), PQEncryption (..), PQSupport (..), pattern IKPQOff, pattern IKPQOn, pattern PQEncOff, pattern PQEncOn, pattern PQSupportOff, pattern PQSupportOn)
 import qualified Simplex.Messaging.Crypto.Ratchet as CR
+import Simplex.Messaging.Encoding
 import Simplex.Messaging.Encoding.String
 import Simplex.Messaging.Notifications.Transport (NTFVersion, pattern VersionNTF)
-import Simplex.Messaging.Protocol (BasicAuth, ErrorType (..), MsgBody, ProtocolServer (..), SubscriptionMode (..), supportedSMPClientVRange)
+import Simplex.Messaging.Protocol (BasicAuth, ErrorType (..), MsgBody, ProtocolServer (..), SubscriptionMode (..), initialSMPClientVersion, srvHostnamesSMPClientVersion, supportedSMPClientVRange)
 import qualified Simplex.Messaging.Protocol as SMP
 import Simplex.Messaging.Server.Env.STM (AServerStoreCfg (..), AStoreType (..), ServerConfig (..), ServerStoreCfg (..), StorePaths (..))
 import Simplex.Messaging.Server.Expiration
 import Simplex.Messaging.Server.MsgStore.Types (SMSType (..), SQSType (..))
 import Simplex.Messaging.Server.QueueStore.QueueInfo
-import Simplex.Messaging.Transport (ATransport (..), SMPVersion, VersionSMP, authCmdsSMPVersion, currentServerSMPRelayVersion, minClientSMPRelayVersion, minServerSMPRelayVersion, sndAuthKeySMPVersion, supportedSMPHandshakes)
+import Simplex.Messaging.Transport (ATransport (..), SMPVersion, VersionSMP, authCmdsSMPVersion, currentServerSMPRelayVersion, minClientSMPRelayVersion, minServerSMPRelayVersion, sendingProxySMPVersion, sndAuthKeySMPVersion, supportedSMPHandshakes, supportedServerSMPRelayVRange)
 import Simplex.Messaging.Util (bshow, diffToMicroseconds)
 import Simplex.Messaging.Version (VersionRange (..))
 import qualified Simplex.Messaging.Version as V
@@ -201,7 +203,7 @@ pattern Rcvd :: AgentMsgId -> AEvent 'AEConn
 pattern Rcvd agentMsgId <- RCVD MsgMeta {integrity = MsgOk} [MsgReceipt {agentMsgId, msgRcptStatus = MROk}]
 
 smpCfgVPrev :: ProtocolClientConfig SMPVersion
-smpCfgVPrev = (smpCfg agentCfg) {clientALPN = Nothing, serverVRange = prevRange $ serverVRange $ smpCfg agentCfg}
+smpCfgVPrev = (smpCfg agentCfg) {serverVRange = prevRange $ serverVRange $ smpCfg agentCfg}
 
 ntfCfgVPrev :: ProtocolClientConfig NTFVersion
 ntfCfgVPrev = (ntfCfg agentCfg) {clientALPN = Nothing, serverVRange = V.mkVersionRange (VersionNTF 1) (VersionNTF 1)}
@@ -249,8 +251,10 @@ inAnyOrder g rs = withFrozenCallStack $ do
     expected :: a -> (a -> Bool) -> Bool
     expected r rp = rp r
 
-createConnection :: AgentClient -> UserId -> Bool -> SConnectionMode c -> Maybe CRClientData -> SubscriptionMode -> AE (ConnId, ConnectionRequestUri c)
-createConnection c userId enableNtfs cMode clientData = A.createConnection c userId enableNtfs cMode clientData (IKNoPQ PQSupportOn)
+createConnection :: ConnectionModeI c => AgentClient -> UserId -> Bool -> SConnectionMode c -> Maybe CRClientData -> SubscriptionMode -> AE (ConnId, ConnectionRequestUri c)
+createConnection c userId enableNtfs cMode clientData subMode = do
+  (connId, CCLink cReq _) <- A.createConnection c userId enableNtfs cMode Nothing clientData (IKNoPQ PQSupportOn) subMode
+  pure (connId, cReq)
 
 joinConnection :: AgentClient -> UserId -> Bool -> ConnectionRequestUri c -> ConnInfo -> SubscriptionMode -> AE (ConnId, SndQueueSecured)
 joinConnection c userId enableNtfs cReq connInfo subMode = do
@@ -306,6 +310,16 @@ functionalAPITests ps = do
       testAsyncServerOffline ps
     it "should restore confirmation after client restart" $
       testAllowConnectionClientRestart ps
+  describe "Short connection links" $ do
+    describe "should connect via 1-time short link" $ testProxyMatrix ps testInviationShortLink
+    describe "should connect via 1-time short link with async join" $ testProxyMatrix ps testInviationShortLinkAsync
+    describe "should connect via contact short link" $ testProxyMatrix ps testContactShortLink
+    describe "should add short link to existing contact and connect" $ testProxyMatrix ps testAddContactShortLink
+    describe "try to create 1-time short link with prev versions" $ testProxyMatrixWithPrev ps testInviationShortLinkPrev
+    describe "server restart" $ do
+      it "should get 1-time link data after restart" $ testInviationShortLinkRestart ps
+      it "should connect via contact short link after restart" $ testContactShortLinkRestart ps
+      it "should connect via added contact short link after restart" $ testAddContactShortLinkRestart ps
   describe "Message delivery" $ do
     describe "update connection agent version on received messages" $ do
       it "should increase if compatible, shouldn'ps decrease" $
@@ -491,21 +505,21 @@ canCreateQueue allowNew (srvAuth, _) (clntAuth, _) =
 
 testMatrix2 :: HasCallStack => (ATransport, AStoreType) -> (PQSupport -> SndQueueSecured -> Bool -> AgentClient -> AgentClient -> AgentMsgId -> IO ()) -> Spec
 testMatrix2 ps runTest = do
-  it "current, via proxy" $ withSmpServerProxy ps $ runTestCfgServers2 agentCfg agentCfg (initAgentServersProxy SPMAlways SPFProhibit) 1 $ runTest PQSupportOn True True
-  it "v8, via proxy" $ withSmpServerProxy ps $ runTestCfgServers2 agentProxyCfgV8 agentProxyCfgV8 (initAgentServersProxy SPMAlways SPFProhibit) 3 $ runTest PQSupportOn False True
+  it "current, via proxy" $ withSmpServerProxy ps $ runTestCfgServers2 agentCfg agentCfg initAgentServersProxy 1 $ runTest PQSupportOn True True
+  it "v8, via proxy" $ withSmpServerProxy ps $ runTestCfgServers2 agentProxyCfgV8 agentProxyCfgV8 initAgentServersProxy 3 $ runTest PQSupportOn False True
   it "current" $ withSmpServer ps $ runTestCfg2 agentCfg agentCfg 1 $ runTest PQSupportOn True False
-  it "prev" $ withSmpServer ps $ runTestCfg2 agentCfgVPrev agentCfgVPrev 3 $ runTest PQSupportOff False False
-  it "prev to current" $ withSmpServer ps $ runTestCfg2 agentCfgVPrev agentCfg 3 $ runTest PQSupportOff False False
-  it "current to prev" $ withSmpServer ps $ runTestCfg2 agentCfg agentCfgVPrev 3 $ runTest PQSupportOff False False
+  it "prev" $ withSmpServer ps $ runTestCfg2 agentCfgVPrev agentCfgVPrev 1 $ runTest PQSupportOff False False
+  it "prev to current" $ withSmpServer ps $ runTestCfg2 agentCfgVPrev agentCfg 1 $ runTest PQSupportOff False False
+  it "current to prev" $ withSmpServer ps $ runTestCfg2 agentCfg agentCfgVPrev 1 $ runTest PQSupportOff False False
 
 testMatrix2Stress :: HasCallStack => (ATransport, AStoreType) -> (PQSupport -> SndQueueSecured -> Bool -> AgentClient -> AgentClient -> AgentMsgId -> IO ()) -> Spec
 testMatrix2Stress ps runTest = do
-  it "current, via proxy" $ withSmpServerProxy ps $ runTestCfgServers2 aCfg aCfg (initAgentServersProxy SPMAlways SPFProhibit) 1 $ runTest PQSupportOn True True
-  it "v8, via proxy" $ withSmpServerProxy ps $ runTestCfgServers2 aProxyCfgV8 aProxyCfgV8 (initAgentServersProxy SPMAlways SPFProhibit) 3 $ runTest PQSupportOn False True
+  it "current, via proxy" $ withSmpServerProxy ps $ runTestCfgServers2 aCfg aCfg initAgentServersProxy 1 $ runTest PQSupportOn True True
+  it "v8, via proxy" $ withSmpServerProxy ps $ runTestCfgServers2 aProxyCfgV8 aProxyCfgV8 initAgentServersProxy 1 $ runTest PQSupportOn False True
   it "current" $ withSmpServer ps $ runTestCfg2 aCfg aCfg 1 $ runTest PQSupportOn True False
-  it "prev" $ withSmpServer ps $ runTestCfg2 aCfgVPrev aCfgVPrev 3 $ runTest PQSupportOff False False
-  it "prev to current" $ withSmpServer ps $ runTestCfg2 aCfgVPrev aCfg 3 $ runTest PQSupportOff False False
-  it "current to prev" $ withSmpServer ps $ runTestCfg2 aCfg aCfgVPrev 3 $ runTest PQSupportOff False False
+  it "prev" $ withSmpServer ps $ runTestCfg2 aCfgVPrev aCfgVPrev 1 $ runTest PQSupportOff False False
+  it "prev to current" $ withSmpServer ps $ runTestCfg2 aCfgVPrev aCfg 1 $ runTest PQSupportOff False False
+  it "current to prev" $ withSmpServer ps $ runTestCfg2 aCfg aCfgVPrev 1 $ runTest PQSupportOff False False
   where
     aCfg = agentCfg {messageRetryInterval = fastMessageRetryInterval}
     aProxyCfgV8 = agentProxyCfgV8 {messageRetryInterval = fastMessageRetryInterval}
@@ -514,23 +528,41 @@ testMatrix2Stress ps runTest = do
 testBasicMatrix2 :: HasCallStack => (ATransport, AStoreType) -> (SndQueueSecured -> AgentClient -> AgentClient -> AgentMsgId -> IO ()) -> Spec
 testBasicMatrix2 ps runTest = do
   it "current" $ withSmpServer ps $ runTestCfg2 agentCfg agentCfg 1 $ runTest True
-  it "prev" $ withSmpServer ps $ runTestCfg2 agentCfgVPrevPQ agentCfgVPrevPQ 3 $ runTest False
-  it "prev to current" $ withSmpServer ps $ runTestCfg2 agentCfgVPrevPQ agentCfg 3 $ runTest False
-  it "current to prev" $ withSmpServer ps $ runTestCfg2 agentCfg agentCfgVPrevPQ 3 $ runTest False
+  it "prev" $ withSmpServer ps $ runTestCfg2 agentCfgVPrevPQ agentCfgVPrevPQ 1 $ runTest False
+  it "prev to current" $ withSmpServer ps $ runTestCfg2 agentCfgVPrevPQ agentCfg 1 $ runTest False
+  it "current to prev" $ withSmpServer ps $ runTestCfg2 agentCfg agentCfgVPrevPQ 1 $ runTest False
 
 testRatchetMatrix2 :: HasCallStack => (ATransport, AStoreType) -> (PQSupport -> SndQueueSecured -> Bool -> AgentClient -> AgentClient -> AgentMsgId -> IO ()) -> Spec
 testRatchetMatrix2 ps runTest = do
-  it "current, via proxy" $ withSmpServerProxy ps $ runTestCfgServers2 agentCfg agentCfg (initAgentServersProxy SPMAlways SPFProhibit) 1 $ runTest PQSupportOn True True
-  it "v8, via proxy" $ withSmpServerProxy ps $ runTestCfgServers2 agentProxyCfgV8 agentProxyCfgV8 (initAgentServersProxy SPMAlways SPFProhibit) 3 $ runTest PQSupportOn False True
+  it "current, via proxy" $ withSmpServerProxy ps $ runTestCfgServers2 agentCfg agentCfg initAgentServersProxy 1 $ runTest PQSupportOn True True
+  it "v8, via proxy" $ withSmpServerProxy ps $ runTestCfgServers2 agentProxyCfgV8 agentProxyCfgV8 initAgentServersProxy 3 $ runTest PQSupportOn False True
   it "ratchet current" $ withSmpServer ps $ runTestCfg2 agentCfg agentCfg 1 $ runTest PQSupportOn True False
   it "ratchet prev" $ withSmpServer ps $ runTestCfg2 agentCfgRatchetVPrev agentCfgRatchetVPrev 1 $ runTest PQSupportOff True False
   it "ratchets prev to current" $ withSmpServer ps $ runTestCfg2 agentCfgRatchetVPrev agentCfg 1 $ runTest PQSupportOff True False
   it "ratchets current to prev" $ withSmpServer ps $ runTestCfg2 agentCfg agentCfgRatchetVPrev 1 $ runTest PQSupportOff True False
 
 testServerMatrix2 :: HasCallStack => (ATransport, AStoreType) -> (InitialAgentServers -> IO ()) -> Spec
-testServerMatrix2 ps@(t, ASType qs _ms) runTest = do
+testServerMatrix2 ps runTest = do
   it "1 server" $ withSmpServer ps $ runTest initAgentServers
-  it "2 servers" $ withSmpServer ps $ withSmpServerConfigOn t (cfgJ2QS qs) testPort2 $ \_ -> runTest initAgentServers2
+  it "2 servers" $ withSmpServers2 ps $ runTest initAgentServers2
+
+testProxyMatrix :: HasCallStack => (ATransport, AStoreType) -> (Bool -> AgentClient -> AgentClient -> IO ()) -> Spec
+testProxyMatrix ps runTest = do
+  it "2 servers, directly" $ withSmpServers2 ps $ withAgentClientsServers2 (agentCfg, initAgentServers) (agentCfg, initAgentServers2) $ runTest False
+  it "2 servers, via proxy" $ withSmpServersProxy2 ps $ withAgentClientsServers2 (agentCfg, initAgentServersProxy) (agentCfg, initAgentServersProxy2) $ runTest True
+
+testProxyMatrixWithPrev :: HasCallStack => (ATransport, AStoreType) -> (Bool -> Bool -> AgentClient -> AgentClient -> IO ()) -> Spec
+testProxyMatrixWithPrev ps@(t, msType@(ASType qs _ms)) runTest = do
+  it "2 servers, directly, curr clients, prev servers" $ withSmpServers2Prev $ withAgentClientsServers2 (agentCfg, initAgentServers) (agentCfg, initAgentServers2) $ runTest False True
+  it "2 servers, via proxy, curr clients, prev servers" $ withSmpServersProxy2Prev $ withAgentClientsServers2 (agentCfg, initAgentServersProxy) (agentCfg, initAgentServersProxy2) $ runTest True True
+  it "2 servers, directly, prev clients, curr servers" $ withSmpServers2 ps $ withAgentClientsServers2 (agentCfgVPrevPQ, initAgentServers) (agentCfgVPrevPQ, initAgentServers2) $ runTest False False
+  it "2 servers, via proxy, prev clients, curr servers" $ withSmpServersProxy2 ps $ withAgentClientsServers2 (agentCfgVPrevPQ, initAgentServersProxy) (agentCfgVPrevPQ, initAgentServersProxy2) $ runTest True False
+  where
+    prev cfg' = cfg' {smpServerVRange = prevRange supportedServerSMPRelayVRange}
+    withSmpServers2Prev a = withServers2 (prev $ cfgMS msType) (prev $ cfgJ2QS qs) a
+    withSmpServersProxy2Prev a = withServers2 (prev $ proxyCfgMS msType) (prev $ proxyCfgJ2QS qs) a
+    withServers2 cfg1 cfg2 a =
+      withSmpServerConfigOn t cfg1 testPort $ \_ -> withSmpServerConfigOn t cfg2 testPort2 $ \_ -> a
 
 testPQMatrix2 :: HasCallStack => (ATransport, AStoreType) -> (HasCallStack => (AgentClient, InitialKeys) -> (AgentClient, PQSupport) -> AgentMsgId -> IO ()) -> Spec
 testPQMatrix2 = pqMatrix2_ True
@@ -548,7 +580,7 @@ pqMatrix2_ pqInv ps test = do
     it "pq-inv/dh handshake" $ runTest $ \a b -> test (a, IKUsePQ) (b, PQSupportOff)
     it "pq-inv/pq handshake" $ runTest $ \a b -> test (a, IKUsePQ) (b, PQSupportOn)
   where
-    runTest = withSmpServerProxy ps . runTestCfgServers2 agentProxyCfgV8 agentProxyCfgV8 (initAgentServersProxy SPMAlways SPFProhibit) 3
+    runTest = withSmpServerProxy ps . runTestCfgServers2 agentProxyCfgV8 agentProxyCfgV8 initAgentServersProxy 3
 
 testPQMatrix3 ::
   HasCallStack =>
@@ -569,7 +601,7 @@ testPQMatrix3 ps test = do
       withSmpServerProxy ps $
         runTestCfgServers2 agentProxyCfgV8 agentProxyCfgV8 servers 3 $ \a b baseMsgId ->
           withAgent 3 agentProxyCfgV8 servers testDB3 $ \c -> test' a b c baseMsgId
-    servers = initAgentServersProxy SPMAlways SPFProhibit
+    servers = initAgentServersProxy
 
 runTestCfg2 :: HasCallStack => AgentConfig -> AgentConfig -> AgentMsgId -> (HasCallStack => AgentClient -> AgentClient -> AgentMsgId -> IO ()) -> IO ()
 runTestCfg2 aCfg bCfg = runTestCfgServers2 aCfg bCfg initAgentServers
@@ -586,6 +618,12 @@ withAgentClientsCfgServers2 aCfg bCfg servers runTest =
     withAgent 2 bCfg servers testDB2 $ \b ->
       runTest a b
 
+withAgentClientsServers2 :: HasCallStack => (AgentConfig, InitialAgentServers) -> (AgentConfig, InitialAgentServers) -> (HasCallStack => AgentClient -> AgentClient -> IO a) -> IO a
+withAgentClientsServers2 (aCfg, aServers) (bCfg, bServers) runTest =
+  withAgent 1 aCfg aServers testDB $ \a ->
+    withAgent 2 bCfg bServers testDB2 $ \b ->
+      runTest a b
+
 withAgentClientsCfg2 :: HasCallStack => AgentConfig -> AgentConfig -> (HasCallStack => AgentClient -> AgentClient -> IO a) -> IO a
 withAgentClientsCfg2 aCfg bCfg = withAgentClientsCfgServers2 aCfg bCfg initAgentServers
 {-# INLINE withAgentClientsCfg2 #-}
@@ -607,7 +645,7 @@ runAgentClientTest pqSupport sqSecured viaProxy alice bob baseId =
 runAgentClientTestPQ :: HasCallStack => SndQueueSecured -> Bool -> (AgentClient, InitialKeys) -> (AgentClient, PQSupport) -> AgentMsgId -> IO ()
 runAgentClientTestPQ sqSecured viaProxy (alice, aPQ) (bob, bPQ) baseId =
   runRight_ $ do
-    (bobId, qInfo) <- A.createConnection alice 1 True SCMInvitation Nothing aPQ SMSubscribe
+    (bobId, CCLink qInfo Nothing) <- A.createConnection alice 1 True SCMInvitation Nothing Nothing aPQ SMSubscribe
     aliceId <- A.prepareConnectionToJoin bob 1 True qInfo bPQ
     sqSecured' <- A.joinConnection bob 1 aliceId True qInfo "bob's connInfo" bPQ SMSubscribe
     liftIO $ sqSecured' `shouldBe` sqSecured
@@ -809,7 +847,7 @@ runAgentClientContactTest pqSupport sqSecured viaProxy alice bob baseId =
 runAgentClientContactTestPQ :: HasCallStack => SndQueueSecured -> Bool -> PQSupport -> (AgentClient, InitialKeys) -> (AgentClient, PQSupport) -> AgentMsgId -> IO ()
 runAgentClientContactTestPQ sqSecured viaProxy reqPQSupport (alice, aPQ) (bob, bPQ) baseId =
   runRight_ $ do
-    (_, qInfo) <- A.createConnection alice 1 True SCMContact Nothing aPQ SMSubscribe
+    (_, CCLink qInfo Nothing) <- A.createConnection alice 1 True SCMContact Nothing Nothing aPQ SMSubscribe
     aliceId <- A.prepareConnectionToJoin bob 1 True qInfo bPQ
     sqSecuredJoin <- A.joinConnection bob 1 aliceId True qInfo "bob's connInfo" bPQ SMSubscribe
     liftIO $ sqSecuredJoin `shouldBe` False -- joining via contact address connection
@@ -853,7 +891,7 @@ runAgentClientContactTestPQ sqSecured viaProxy reqPQSupport (alice, aPQ) (bob, b
 
 runAgentClientContactTestPQ3 :: HasCallStack => Bool -> (AgentClient, InitialKeys) -> (AgentClient, PQSupport) -> (AgentClient, PQSupport) -> AgentMsgId -> IO ()
 runAgentClientContactTestPQ3 viaProxy (alice, aPQ) (bob, bPQ) (tom, tPQ) baseId = runRight_ $ do
-  (_, qInfo) <- A.createConnection alice 1 True SCMContact Nothing aPQ SMSubscribe
+  (_, CCLink qInfo Nothing) <- A.createConnection alice 1 True SCMContact Nothing Nothing aPQ SMSubscribe
   (bAliceId, bobId, abPQEnc) <- connectViaContact bob bPQ qInfo
   sentMessages abPQEnc alice bobId bob bAliceId
   (tAliceId, tomId, atPQEnc) <- connectViaContact tom tPQ qInfo
@@ -906,7 +944,7 @@ noMessages_ ingoreQCONT c err = tryGet `shouldReturn` ()
 testRejectContactRequest :: HasCallStack => IO ()
 testRejectContactRequest =
   withAgentClients2 $ \alice bob -> runRight_ $ do
-    (addrConnId, qInfo) <- A.createConnection alice 1 True SCMContact Nothing IKPQOn SMSubscribe
+    (addrConnId, CCLink qInfo Nothing) <- A.createConnection alice 1 True SCMContact Nothing Nothing IKPQOn SMSubscribe
     aliceId <- A.prepareConnectionToJoin bob 1 True qInfo PQSupportOn
     sqSecured <- A.joinConnection bob 1 aliceId True qInfo "bob's connInfo" PQSupportOn SMSubscribe
     liftIO $ sqSecured `shouldBe` False -- joining via contact address connection
@@ -1073,6 +1111,201 @@ testAllowConnectionClientRestart ps@(t, ASType qsType _) = do
     disposeAgentClient alice2
     disposeAgentClient bob
 
+testInviationShortLink :: HasCallStack => Bool -> AgentClient -> AgentClient -> IO ()
+testInviationShortLink viaProxy a b =
+  withAgent 3 agentCfg initAgentServers testDB3 $ \c -> do
+    let userData = "some user data"
+    (bId, CCLink connReq (Just shortLink)) <- runRight $ A.createConnection a 1 True SCMInvitation (Just userData) Nothing CR.IKUsePQ SMSubscribe
+    (connReq', connData') <- runRight $ getConnShortLink b 1 shortLink
+    strDecode (strEncode shortLink) `shouldBe` Right shortLink
+    connReq' `shouldBe` connReq
+    linkUserData connData' `shouldBe` userData
+    -- same user can get invitation link again
+    (connReq2, connData2) <- runRight $ getConnShortLink b 1 shortLink
+    connReq2 `shouldBe` connReq
+    linkUserData connData2 `shouldBe` userData
+    -- another user cannot get the same invitation link
+    runExceptT (getConnShortLink c 1 shortLink) >>= \case
+      Left (SMP _ AUTH) -> pure ()
+      r -> liftIO $ expectationFailure ("unexpected result " <> show r)
+    runRight $ testJoinConn_ viaProxy True a bId b connReq
+
+testJoinConn_ :: Bool -> Bool -> AgentClient -> ConnId -> AgentClient -> ConnectionRequestUri c -> ExceptT AgentErrorType IO ()
+testJoinConn_ viaProxy sndSecure a bId b connReq = do
+  aId <- A.prepareConnectionToJoin b 1 True connReq PQSupportOn
+  sndSecure' <- A.joinConnection b 1 aId True connReq "bob's connInfo" PQSupportOn SMSubscribe
+  liftIO $ sndSecure' `shouldBe` sndSecure
+  ("", _, CONF confId _ "bob's connInfo") <- get a
+  allowConnection a bId confId "alice's connInfo"
+  get a ##> ("", bId, CON)
+  get b ##> ("", aId, INFO "alice's connInfo")
+  get b ##> ("", aId, CON)
+  exchangeGreetingsViaProxy viaProxy a bId b aId
+
+testInviationShortLinkPrev :: HasCallStack => Bool -> Bool -> AgentClient -> AgentClient -> IO ()
+testInviationShortLinkPrev viaProxy sndSecure a b = runRight_ $ do
+  let userData = "some user data"
+  -- can't create short link with previous version
+  (bId, CCLink connReq Nothing) <- A.createConnection a 1 True SCMInvitation (Just userData) Nothing CR.IKPQOn SMSubscribe
+  testJoinConn_ viaProxy sndSecure a bId b connReq
+
+testInviationShortLinkAsync :: HasCallStack => Bool -> AgentClient -> AgentClient -> IO ()
+testInviationShortLinkAsync viaProxy a b = do
+  let userData = "some user data"
+  (bId, CCLink connReq (Just shortLink)) <- runRight $ A.createConnection a 1 True SCMInvitation (Just userData) Nothing CR.IKUsePQ SMSubscribe
+  (connReq', connData') <- runRight $ getConnShortLink b 1 shortLink
+  strDecode (strEncode shortLink) `shouldBe` Right shortLink
+  connReq' `shouldBe` connReq
+  linkUserData connData' `shouldBe` userData
+  runRight $ do
+    aId <- A.joinConnectionAsync b 1 "123" True connReq "bob's connInfo" PQSupportOn SMSubscribe
+    get b =##> \case ("123", c, JOINED sndSecure) -> c == aId && sndSecure; _ -> False
+    ("", _, CONF confId _ "bob's connInfo") <- get a
+    allowConnection a bId confId "alice's connInfo"
+    get a ##> ("", bId, CON)
+    get b ##> ("", aId, INFO "alice's connInfo")
+    get b ##> ("", aId, CON)
+    exchangeGreetingsViaProxy viaProxy a bId b aId
+
+testContactShortLink :: HasCallStack => Bool -> AgentClient -> AgentClient -> IO ()
+testContactShortLink viaProxy a b =
+  withAgent 3 agentCfg initAgentServers testDB3 $ \c -> do
+    let userData = "some user data"
+    (contactId, CCLink connReq0 (Just shortLink)) <- runRight $ A.createConnection a 1 True SCMContact (Just userData) Nothing CR.IKPQOn SMSubscribe
+    Right connReq <- pure $ smpDecode (smpEncode connReq0)
+    (connReq', connData') <- runRight $ getConnShortLink b 1 shortLink
+    strDecode (strEncode shortLink) `shouldBe` Right shortLink
+    connReq' `shouldBe` connReq
+    linkUserData connData' `shouldBe` userData
+    -- same user can get contact link again
+    (connReq2, connData2) <- runRight $ getConnShortLink b 1 shortLink
+    connReq2 `shouldBe` connReq
+    linkUserData connData2 `shouldBe` userData
+    -- another user can get the same contact link
+    (connReq3, connData3) <- runRight $ getConnShortLink c 1 shortLink
+    connReq3 `shouldBe` connReq
+    linkUserData connData3 `shouldBe` userData
+    runRight $ do
+      (aId, sndSecure) <- joinConnection b 1 True connReq "bob's connInfo" SMSubscribe
+      liftIO $ sndSecure `shouldBe` False
+      ("", _, REQ invId _ "bob's connInfo") <- get a
+      bId <- A.prepareConnectionToAccept a True invId PQSupportOn
+      sndSecure' <- acceptContact a bId True invId "alice's connInfo" PQSupportOn SMSubscribe
+      liftIO $ sndSecure' `shouldBe` True
+      ("", _, CONF confId  _ "alice's connInfo") <- get b
+      allowConnection b aId confId "bob's connInfo"
+      get a ##> ("", bId, INFO "bob's connInfo")
+      get a ##> ("", bId, CON)
+      get b ##> ("", aId, CON)
+      exchangeGreetingsViaProxy viaProxy a bId b aId
+    -- update user data
+    let updatedData = "updated user data"
+    shortLink' <- runRight $ setContactShortLink a contactId updatedData
+    shortLink' `shouldBe` shortLink
+    (connReq4, updatedConnData') <- runRight $ getConnShortLink c 1 shortLink
+    connReq4 `shouldBe` connReq
+    linkUserData updatedConnData' `shouldBe` updatedData
+    -- one more time
+    shortLink2 <- runRight $ setContactShortLink a contactId updatedData
+    shortLink2 `shouldBe` shortLink
+    -- delete short link
+    runRight_ $ deleteContactShortLink a contactId
+    Left (SMP _ AUTH) <- runExceptT $ getConnShortLink c 1 shortLink
+    pure ()
+
+testAddContactShortLink :: HasCallStack => Bool -> AgentClient -> AgentClient -> IO ()
+testAddContactShortLink viaProxy a b =
+  withAgent 3 agentCfg initAgentServers testDB3 $ \c -> do
+    (contactId, CCLink connReq0 Nothing) <- runRight $ A.createConnection a 1 True SCMContact Nothing Nothing CR.IKPQOn SMSubscribe
+    Right connReq <- pure $ smpDecode (smpEncode connReq0) --
+    let userData = "some user data"
+    shortLink <- runRight $ setContactShortLink a contactId userData
+    (connReq', connData') <- runRight $ getConnShortLink b 1 shortLink
+    strDecode (strEncode shortLink) `shouldBe` Right shortLink
+    connReq' `shouldBe` connReq
+    linkUserData connData' `shouldBe` userData
+    -- same user can get contact link again
+    (connReq2, connData2) <- runRight $ getConnShortLink b 1 shortLink
+    connReq2 `shouldBe` connReq
+    linkUserData connData2 `shouldBe` userData
+    -- another user can get the same contact link
+    (connReq3, connData3) <- runRight $ getConnShortLink c 1 shortLink
+    connReq3 `shouldBe` connReq
+    linkUserData connData3 `shouldBe` userData
+    runRight $ do
+      (aId, sndSecure) <- joinConnection b 1 True connReq "bob's connInfo" SMSubscribe
+      liftIO $ sndSecure `shouldBe` False
+      ("", _, REQ invId _ "bob's connInfo") <- get a
+      bId <- A.prepareConnectionToAccept a True invId PQSupportOn
+      sndSecure' <- acceptContact a bId True invId "alice's connInfo" PQSupportOn SMSubscribe
+      liftIO $ sndSecure' `shouldBe` True
+      ("", _, CONF confId  _ "alice's connInfo") <- get b
+      allowConnection b aId confId "bob's connInfo"
+      get a ##> ("", bId, INFO "bob's connInfo")
+      get a ##> ("", bId, CON)
+      get b ##> ("", aId, CON)
+      exchangeGreetingsViaProxy viaProxy a bId b aId
+    -- update user data
+    let updatedData = "updated user data"
+    shortLink' <- runRight $ setContactShortLink a contactId updatedData
+    shortLink' `shouldBe` shortLink
+    (connReq4, updatedConnData') <- runRight $ getConnShortLink c 1 shortLink
+    connReq4 `shouldBe` connReq
+    linkUserData updatedConnData' `shouldBe` updatedData
+
+testInviationShortLinkRestart :: HasCallStack => (ATransport, AStoreType) -> IO ()
+testInviationShortLinkRestart ps = withAgentClients2 $ \a b -> do
+  let userData = "some user data"
+  (bId, CCLink connReq (Just shortLink)) <- withSmpServer ps $
+    runRight $ A.createConnection a 1 True SCMInvitation (Just userData) Nothing CR.IKUsePQ SMOnlyCreate
+  withSmpServer ps $ do
+    runRight_ $ subscribeConnection a bId
+    (connReq', connData') <- runRight $ getConnShortLink b 1 shortLink
+    strDecode (strEncode shortLink) `shouldBe` Right shortLink
+    connReq' `shouldBe` connReq
+    linkUserData connData' `shouldBe` userData
+
+testContactShortLinkRestart :: HasCallStack => (ATransport, AStoreType) -> IO ()
+testContactShortLinkRestart ps = withAgentClients2 $ \a b -> do
+  let userData = "some user data"
+  (contactId, CCLink connReq0 (Just shortLink)) <- withSmpServer ps $
+    runRight $ A.createConnection a 1 True SCMContact (Just userData) Nothing CR.IKPQOn SMOnlyCreate
+  Right connReq <- pure $ smpDecode (smpEncode connReq0)
+  let updatedData = "updated user data"
+  withSmpServer ps $ do
+    (connReq', connData') <- runRight $ getConnShortLink b 1 shortLink
+    strDecode (strEncode shortLink) `shouldBe` Right shortLink
+    connReq' `shouldBe` connReq
+    linkUserData connData' `shouldBe` userData
+    -- update user data
+    shortLink' <- runRight $ setContactShortLink a contactId updatedData
+    shortLink' `shouldBe` shortLink
+  withSmpServer ps $ do
+    (connReq4, updatedConnData') <- runRight $ getConnShortLink b 1 shortLink
+    connReq4 `shouldBe` connReq
+    linkUserData updatedConnData' `shouldBe` updatedData
+
+testAddContactShortLinkRestart :: HasCallStack => (ATransport, AStoreType) -> IO ()
+testAddContactShortLinkRestart ps = withAgentClients2 $ \a b -> do
+  let userData = "some user data"
+  ((contactId, CCLink connReq0 Nothing), shortLink) <- withSmpServer ps $ runRight $ do
+    r@(contactId, _) <- A.createConnection a 1 True SCMContact Nothing Nothing CR.IKPQOn SMOnlyCreate
+    (r,) <$> setContactShortLink a contactId userData
+  Right connReq <- pure $ smpDecode (smpEncode connReq0)
+  let updatedData = "updated user data"
+  withSmpServer ps $ do
+    (connReq', connData') <- runRight $ getConnShortLink b 1 shortLink
+    strDecode (strEncode shortLink) `shouldBe` Right shortLink
+    connReq' `shouldBe` connReq
+    linkUserData connData' `shouldBe` userData
+    -- update user data
+    shortLink' <- runRight $ setContactShortLink a contactId updatedData
+    shortLink' `shouldBe` shortLink
+  withSmpServer ps $ do
+    (connReq4, updatedConnData') <- runRight $ getConnShortLink b 1 shortLink
+    connReq4 `shouldBe` connReq
+    linkUserData updatedConnData' `shouldBe` updatedData
+
 testIncreaseConnAgentVersion :: HasCallStack => (ATransport, AStoreType) -> IO ()
 testIncreaseConnAgentVersion ps = do
   alice <- getSMPAgentClient' 1 agentCfg {smpAgentVRange = mkVersionRange 1 2} initAgentServers testDB
@@ -1760,7 +1993,7 @@ makeConnectionForUsers = makeConnectionForUsers_ PQSupportOn True
 
 makeConnectionForUsers_ :: HasCallStack => PQSupport -> SndQueueSecured -> AgentClient -> UserId -> AgentClient -> UserId -> ExceptT AgentErrorType IO (ConnId, ConnId)
 makeConnectionForUsers_ pqSupport sqSecured alice aliceUserId bob bobUserId = do
-  (bobId, qInfo) <- A.createConnection alice aliceUserId True SCMInvitation Nothing (CR.IKNoPQ pqSupport) SMSubscribe
+  (bobId, CCLink qInfo Nothing) <- A.createConnection alice aliceUserId True SCMInvitation Nothing Nothing (CR.IKNoPQ pqSupport) SMSubscribe
   aliceId <- A.prepareConnectionToJoin bob bobUserId True qInfo pqSupport
   sqSecured' <- A.joinConnection bob bobUserId aliceId True qInfo "bob's connInfo" pqSupport SMSubscribe
   liftIO $ sqSecured' `shouldBe` sqSecured
@@ -2360,8 +2593,8 @@ testWaitDeliveryTimeout2 ps =
 testJoinConnectionAsyncReplyErrorV8 :: HasCallStack => (ATransport, AStoreType) -> IO ()
 testJoinConnectionAsyncReplyErrorV8 ps@(t, ASType qsType _) = do
   let initAgentServersSrv2 = initAgentServers {smp = userServers [testSMPServer2]}
-  withAgent 1 agentCfgVPrevPQ initAgentServers testDB $ \a ->
-    withAgent 2 agentCfgVPrevPQ initAgentServersSrv2 testDB2 $ \b -> do
+  withAgent 1 cfg' initAgentServers testDB $ \a ->
+    withAgent 2 cfg' initAgentServersSrv2 testDB2 $ \b -> do
       (aId, bId) <- withSmpServerStoreLogOn ps testPort $ \_ -> runRight $ do
         bId <- createConnectionAsync a 1 "1" True SCMInvitation (IKNoPQ PQSupportOn) SMSubscribe
         ("1", bId', INV (ACR _ qInfo)) <- get a
@@ -2395,6 +2628,12 @@ testJoinConnectionAsyncReplyErrorV8 ps@(t, ASType qsType _) = do
           get b ##> ("", aId, INFO "alice's connInfo")
           get b ##> ("", aId, CON)
           exchangeGreetingsMsgId 4 a bId b aId
+  where
+    cfg' =
+      agentCfgVPrevPQ
+        { smpClientVRange = V.mkVersionRange initialSMPClientVersion srvHostnamesSMPClientVersion, -- before SKEY
+          smpCfg = smpCfgVPrev {serverVRange = V.mkVersionRange minServerSMPRelayVersion sendingProxySMPVersion}  -- before SKEY
+        }
 
 testJoinConnectionAsyncReplyError :: HasCallStack => (ATransport, AStoreType) -> IO ()
 testJoinConnectionAsyncReplyError ps@(t, ASType qsType _) = do
@@ -3335,16 +3574,22 @@ exchangeGreetingsMsgId :: HasCallStack => Int64 -> AgentClient -> ConnId -> Agen
 exchangeGreetingsMsgId = exchangeGreetingsMsgId_ PQEncOn
 
 exchangeGreetingsMsgId_ :: HasCallStack => PQEncryption -> Int64 -> AgentClient -> ConnId -> AgentClient -> ConnId -> ExceptT AgentErrorType IO ()
-exchangeGreetingsMsgId_ pqEnc msgId alice bobId bob aliceId = do
+exchangeGreetingsMsgId_ = exchangeGreetingsViaProxyMsgId_ False
+
+exchangeGreetingsViaProxy :: HasCallStack => Bool -> AgentClient -> ConnId -> AgentClient -> ConnId -> ExceptT AgentErrorType IO ()
+exchangeGreetingsViaProxy viaProxy = exchangeGreetingsViaProxyMsgId_ viaProxy PQEncOn 2 
+
+exchangeGreetingsViaProxyMsgId_ :: HasCallStack => Bool -> PQEncryption -> Int64 -> AgentClient -> ConnId -> AgentClient -> ConnId -> ExceptT AgentErrorType IO ()
+exchangeGreetingsViaProxyMsgId_ viaProxy pqEnc msgId alice bobId bob aliceId = do
   msgId1 <- A.sendMessage alice bobId pqEnc SMP.noMsgFlags "hello"
   liftIO $ msgId1 `shouldBe` (msgId, pqEnc)
-  get alice ##> ("", bobId, SENT msgId)
+  get alice =##> \case ("", c, A.SENT mId srv_) -> c == bobId && mId == msgId && viaProxy == isJust srv_; _ -> False
   get bob =##> \case ("", c, Msg' mId pq "hello") -> c == aliceId && mId == msgId && pq == pqEnc; _ -> False
   ackMessage bob aliceId msgId Nothing
   msgId2 <- A.sendMessage bob aliceId pqEnc SMP.noMsgFlags "hello too"
   let msgId' = msgId + 1
   liftIO $ msgId2 `shouldBe` (msgId', pqEnc)
-  get bob ##> ("", aliceId, SENT msgId')
+  get bob =##> \case ("", c, A.SENT mId srv_) -> c == aliceId && mId == msgId' && viaProxy == isJust srv_; _ -> False
   get alice =##> \case ("", c, Msg' mId pq "hello too") -> c == bobId && mId == msgId' && pq == pqEnc; _ -> False
   ackMessage alice bobId msgId' Nothing
 
diff --git a/tests/AgentTests/NotificationTests.hs b/tests/AgentTests/NotificationTests.hs
index da85d25aab..ea0ebd29b4 100644
--- a/tests/AgentTests/NotificationTests.hs
+++ b/tests/AgentTests/NotificationTests.hs
@@ -175,15 +175,15 @@ testNtfMatrix :: HasCallStack => (ATransport, AStoreType) -> (APNSMockServer ->
 testNtfMatrix ps@(_, msType) runTest = do
   describe "next and current" $ do
     it "curr servers; curr clients" $ runNtfTestCfg ps 1 cfg' ntfServerCfg agentCfg agentCfg runTest
-    it "curr servers; prev clients" $ runNtfTestCfg ps 3 cfg' ntfServerCfg agentCfgVPrevPQ agentCfgVPrevPQ runTest
-    it "prev servers; prev clients" $ runNtfTestCfg ps 3 cfgVPrev' ntfServerCfgVPrev agentCfgVPrevPQ agentCfgVPrevPQ runTest
+    it "curr servers; prev clients" $ runNtfTestCfg ps 1 cfg' ntfServerCfg agentCfgVPrevPQ agentCfgVPrevPQ runTest
+    it "prev servers; prev clients" $ runNtfTestCfg ps 1 cfgVPrev' ntfServerCfgVPrev agentCfgVPrevPQ agentCfgVPrevPQ runTest
     it "prev servers; curr clients" $ runNtfTestCfg ps 1 cfgVPrev' ntfServerCfgVPrev agentCfg agentCfg runTest
     -- servers can be upgraded in any order
-    it "servers: curr SMP, prev NTF; prev clients" $ runNtfTestCfg ps 3 cfg' ntfServerCfgVPrev agentCfgVPrevPQ agentCfgVPrevPQ runTest
-    it "servers: prev SMP, curr NTF; prev clients" $ runNtfTestCfg ps 3 cfgVPrev' ntfServerCfg agentCfgVPrevPQ agentCfgVPrevPQ runTest
+    it "servers: curr SMP, prev NTF; prev clients" $ runNtfTestCfg ps 1 cfg' ntfServerCfgVPrev agentCfgVPrevPQ agentCfgVPrevPQ runTest
+    it "servers: prev SMP, curr NTF; prev clients" $ runNtfTestCfg ps 1 cfgVPrev' ntfServerCfg agentCfgVPrevPQ agentCfgVPrevPQ runTest
     -- one of two clients can be upgraded
-    it "servers: curr SMP, curr NTF; clients: curr/prev" $ runNtfTestCfg ps 3 cfg' ntfServerCfg agentCfg agentCfgVPrevPQ runTest
-    it "servers: curr SMP, curr NTF; clients: prev/curr" $ runNtfTestCfg ps 3 cfg' ntfServerCfg agentCfgVPrevPQ agentCfg runTest
+    it "servers: curr SMP, curr NTF; clients: curr/prev" $ runNtfTestCfg ps 1 cfg' ntfServerCfg agentCfg agentCfgVPrevPQ runTest
+    it "servers: curr SMP, curr NTF; clients: prev/curr" $ runNtfTestCfg ps 1 cfg' ntfServerCfg agentCfgVPrevPQ agentCfg runTest
   where
     cfg' = cfgMS msType
     cfgVPrev' = cfgVPrev msType
diff --git a/tests/AgentTests/SQLiteTests.hs b/tests/AgentTests/SQLiteTests.hs
index 5ead816130..fb6c72996b 100644
--- a/tests/AgentTests/SQLiteTests.hs
+++ b/tests/AgentTests/SQLiteTests.hs
@@ -52,7 +52,7 @@ import Simplex.Messaging.Crypto.File (CryptoFile (..))
 import Simplex.Messaging.Crypto.Ratchet (InitialKeys (..), pattern PQSupportOn)
 import qualified Simplex.Messaging.Crypto.Ratchet as CR
 import Simplex.Messaging.Encoding.String (StrEncoding (..))
-import Simplex.Messaging.Protocol (EntityId (..), SubscriptionMode (..), pattern VersionSMPC)
+import Simplex.Messaging.Protocol (EntityId (..), SubscriptionMode (..), QueueMode (..), pattern VersionSMPC)
 import qualified Simplex.Messaging.Protocol as SMP
 import System.Random
 import Test.Hspec
@@ -226,7 +226,8 @@ rcvQueue1 =
       e2ePrivKey = testPrivDhKey,
       e2eDhSecret = Nothing,
       sndId = EntityId "2345",
-      sndSecure = True,
+      queueMode = Just QMMessaging,
+      shortLink = Nothing,
       status = New,
       dbQueueId = DBNewQueue,
       primary = True,
@@ -244,7 +245,7 @@ sndQueue1 =
       connId = "conn1",
       server = smpServer1,
       sndId = EntityId "3456",
-      sndSecure = True,
+      queueMode = Just QMMessaging,
       sndPublicKey = testPublicAuthKey,
       sndPrivateKey = testPrivateAuthKey,
       e2ePubKey = Nothing,
@@ -404,7 +405,7 @@ testUpgradeRcvConnToDuplex =
               connId = "conn1",
               server = SMPServer "smp.simplex.im" "5223" testKeyHash,
               sndId = EntityId "2345",
-              sndSecure = True,
+              queueMode = Just QMMessaging,
               sndPublicKey = testPublicAuthKey,
               sndPrivateKey = testPrivateAuthKey,
               e2ePubKey = Nothing,
@@ -438,7 +439,8 @@ testUpgradeSndConnToDuplex =
               e2ePrivKey = testPrivDhKey,
               e2eDhSecret = Nothing,
               sndId = EntityId "4567",
-              sndSecure = True,
+              queueMode = Just QMMessaging,
+              shortLink = Nothing,
               status = New,
               dbQueueId = DBNewQueue,
               rcvSwchStatus = Nothing,
diff --git a/tests/AgentTests/SchemaDump.hs b/tests/AgentTests/SchemaDump.hs
index 0b6f4ebc1f..736863364c 100644
--- a/tests/AgentTests/SchemaDump.hs
+++ b/tests/AgentTests/SchemaDump.hs
@@ -4,7 +4,6 @@
 module AgentTests.SchemaDump where
 
 import Control.DeepSeq
-import Control.Exception (bracket_)
 import Control.Monad (unless, void)
 import Data.List (dropWhileEnd)
 import Data.Maybe (fromJust, isJust)
@@ -17,7 +16,7 @@ import Simplex.Messaging.Agent.Store.SQLite.DB (TrackQueries (..))
 import qualified Simplex.Messaging.Agent.Store.SQLite.Migrations as Migrations
 import Simplex.Messaging.Agent.Store.Shared (Migration (..), MigrationConfirmation (..), MigrationsToRun (..), toDownMigration)
 import Simplex.Messaging.Util (ifM)
-import System.Directory (createDirectoryIfMissing, doesFileExist, removeDirectoryRecursive, removeFile)
+import System.Directory (doesFileExist, removeFile)
 import System.Process (readCreateProcess, shell)
 import Test.Hspec
 
@@ -63,12 +62,6 @@ testVerifyLintFKeyIndexes = do
   getLintFKeyIndexes testDB "tests/tmp/agent_lint.sql" `shouldReturn` savedLint
   removeFile testDB
 
-withTmpFiles :: IO () -> IO ()
-withTmpFiles =
-  bracket_
-    (createDirectoryIfMissing False "tests/tmp")
-    (removeDirectoryRecursive "tests/tmp")
-
 testSchemaMigrations :: IO ()
 testSchemaMigrations = do
   let noDownMigrations = dropWhileEnd (\Migration {down} -> isJust down) appMigrations
@@ -115,7 +108,9 @@ testUsersMigrationOld = do
 skipComparisonForDownMigrations :: [String]
 skipComparisonForDownMigrations =
   [ -- on down migration idx_messages_internal_snd_id_ts index moves down to the end of the file
-    "m20230814_indexes"
+    "m20230814_indexes",
+    -- snd_secure and last_broker_ts columns swap order on down migration
+    "m20250322_short_links"
   ]
 
 getSchema :: FilePath -> FilePath -> IO String
diff --git a/tests/AgentTests/ShortLinkTests.hs b/tests/AgentTests/ShortLinkTests.hs
new file mode 100644
index 0000000000..e91472f997
--- /dev/null
+++ b/tests/AgentTests/ShortLinkTests.hs
@@ -0,0 +1,120 @@
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE TypeApplications #-}
+
+module AgentTests.ShortLinkTests (shortLinkTests) where
+
+import AgentTests.ConnectionRequestTests (contactConnRequest, invConnRequest)
+import AgentTests.EqInstances ()
+import Control.Concurrent.STM
+import Control.Monad.Except
+import Simplex.Messaging.Agent.Protocol (AgentErrorType (..), ConnectionMode (..), LinkKey (..), SMPAgentError (..), linkUserData, supportedSMPAgentVRange)
+import qualified Simplex.Messaging.Crypto as C
+import qualified Simplex.Messaging.Crypto.ShortLink as SL
+import Test.Hspec
+
+shortLinkTests :: Spec
+shortLinkTests = do
+  describe "invitation short link" $ do
+    it "should encrypt and decrypt link data" testInvShortLink
+    it "should fail to decrypt invitation data with bad hash" testInvShortLinkBadDataHash
+  describe "contact short link" $ do
+    it "should encrypt and decrypt data" testContactShortLink
+    it "should encrypt updated user data" testUpdateContactShortLink    
+    it "should fail to decrypt contact data with bad hash" testContactShortLinkBadDataHash
+    it "should fail to decrypt contact data with bad signature" testContactShortLinkBadSignature
+
+testInvShortLink :: IO ()
+testInvShortLink = do
+  -- encrypt
+  g <- C.newRandom
+  sigKeys <- atomically $ C.generateKeyPair @'C.Ed25519 g
+  let userData = "some user data"
+      (linkKey, linkData) = SL.encodeSignLinkData sigKeys supportedSMPAgentVRange invConnRequest userData
+      k = SL.invShortLinkKdf linkKey
+  Right srvData <- runExceptT $ SL.encryptLinkData g k linkData
+  -- decrypt
+  Right (connReq, connData') <- pure $ SL.decryptLinkData linkKey k srvData
+  connReq `shouldBe` invConnRequest
+  linkUserData connData' `shouldBe` userData
+
+testInvShortLinkBadDataHash :: IO ()
+testInvShortLinkBadDataHash = do
+  -- encrypt
+  g <- C.newRandom
+  sigKeys <- atomically $ C.generateKeyPair @'C.Ed25519 g
+  let userData = "some user data"
+      (_linkKey, linkData) = SL.encodeSignLinkData sigKeys supportedSMPAgentVRange invConnRequest userData
+  -- different key
+  linkKey <- LinkKey <$> atomically (C.randomBytes 32 g)
+  let k = SL.invShortLinkKdf linkKey
+  Right srvData <- runExceptT $ SL.encryptLinkData g k linkData
+  -- decryption fails
+  SL.decryptLinkData @'CMInvitation linkKey k srvData
+    `shouldBe` Left (AGENT (A_LINK "link data hash"))
+
+testContactShortLink :: IO ()
+testContactShortLink = do
+  -- encrypt
+  g <- C.newRandom
+  sigKeys <- atomically $ C.generateKeyPair @'C.Ed25519 g
+  let userData = "some user data"
+      (linkKey, linkData) = SL.encodeSignLinkData sigKeys supportedSMPAgentVRange contactConnRequest userData
+      (_linkId, k) = SL.contactShortLinkKdf linkKey
+  Right srvData <- runExceptT $ SL.encryptLinkData g k linkData
+  -- decrypt
+  Right (connReq, connData') <- pure $ SL.decryptLinkData linkKey k srvData
+  connReq `shouldBe` contactConnRequest
+  linkUserData connData' `shouldBe` userData
+
+testUpdateContactShortLink :: IO ()
+testUpdateContactShortLink = do
+  -- encrypt
+  g <- C.newRandom
+  sigKeys <- atomically $ C.generateKeyPair @'C.Ed25519 g
+  let userData = "some user data"
+      (linkKey, linkData) = SL.encodeSignLinkData sigKeys supportedSMPAgentVRange contactConnRequest userData
+      (_linkId, k) = SL.contactShortLinkKdf linkKey
+  Right (fd, _ud) <- runExceptT $ SL.encryptLinkData g k linkData
+  -- encrypt updated user data
+  let updatedUserData = "updated user data"
+      signed = SL.encodeSignUserData (snd sigKeys) supportedSMPAgentVRange updatedUserData
+  Right ud' <- runExceptT $ SL.encryptUserData g k signed
+  -- decrypt
+  Right (connReq, connData') <- pure $ SL.decryptLinkData linkKey k (fd, ud')
+  connReq `shouldBe` contactConnRequest
+  linkUserData connData' `shouldBe` updatedUserData
+
+testContactShortLinkBadDataHash :: IO ()
+testContactShortLinkBadDataHash = do
+  -- encrypt
+  g <- C.newRandom
+  sigKeys <- atomically $ C.generateKeyPair @'C.Ed25519 g
+  let userData = "some user data"
+      (_linkKey, linkData) = SL.encodeSignLinkData sigKeys supportedSMPAgentVRange contactConnRequest userData
+  -- different key
+  linkKey <- LinkKey <$> atomically (C.randomBytes 32 g)
+  let (_linkId, k) = SL.contactShortLinkKdf linkKey
+  Right srvData <- runExceptT $ SL.encryptLinkData g k linkData
+  -- decryption fails
+  SL.decryptLinkData @'CMContact linkKey k srvData
+    `shouldBe` Left (AGENT (A_LINK "link data hash"))
+
+testContactShortLinkBadSignature :: IO ()
+testContactShortLinkBadSignature = do
+  -- encrypt
+  g <- C.newRandom
+  sigKeys <- atomically $ C.generateKeyPair @'C.Ed25519 g
+  let userData = "some user data"
+      (linkKey, linkData) = SL.encodeSignLinkData sigKeys supportedSMPAgentVRange contactConnRequest userData
+      (_linkId, k) = SL.contactShortLinkKdf linkKey
+  Right (fd, _ud) <- runExceptT $ SL.encryptLinkData g k linkData
+  -- encrypt updated user data
+  let updatedUserData = "updated user data"
+  -- another signature key
+  (_, pk) <- atomically $ C.generateKeyPair @'C.Ed25519 g
+  let signed = SL.encodeSignUserData pk supportedSMPAgentVRange updatedUserData
+  Right ud' <- runExceptT $ SL.encryptUserData g k signed
+  -- decryption fails
+  SL.decryptLinkData @'CMContact linkKey k (fd, ud')
+    `shouldBe` Left (AGENT (A_LINK "user data signature"))
diff --git a/tests/CoreTests/MsgStoreTests.hs b/tests/CoreTests/MsgStoreTests.hs
index 0ec1031be2..5c0e7f95ba 100644
--- a/tests/CoreTests/MsgStoreTests.hs
+++ b/tests/CoreTests/MsgStoreTests.hs
@@ -3,6 +3,7 @@
 {-# LANGUAGE FlexibleContexts #-}
 {-# LANGUAGE GADTs #-}
 {-# LANGUAGE NamedFieldPuns #-}
+{-# LANGUAGE OverloadedLists #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE PatternSynonyms #-}
 {-# LANGUAGE RankNTypes #-}
@@ -31,7 +32,7 @@ import Data.Time.Clock (addUTCTime)
 import Data.Time.Clock.System (SystemTime (..), getSystemTime)
 import Simplex.Messaging.Crypto (pattern MaxLenBS)
 import qualified Simplex.Messaging.Crypto as C
-import Simplex.Messaging.Protocol (EntityId (..), Message (..), RecipientId, SParty (..), noMsgFlags)
+import Simplex.Messaging.Protocol (EntityId (..), LinkId, Message (..), QueueLinkData, RecipientId, SParty (..), noMsgFlags)
 import Simplex.Messaging.Server (exportMessages, importMessages, printMessageStats)
 import Simplex.Messaging.Server.Env.STM (journalMsgStoreDepth, readWriteQueueStore)
 import Simplex.Messaging.Server.Expiration (ExpirationConfig (..), expireBeforeEpoch)
@@ -39,6 +40,7 @@ import Simplex.Messaging.Server.MsgStore.Journal
 import Simplex.Messaging.Server.MsgStore.STM
 import Simplex.Messaging.Server.MsgStore.Types
 import Simplex.Messaging.Server.QueueStore
+import Simplex.Messaging.Server.QueueStore.QueueInfo
 import Simplex.Messaging.Server.QueueStore.Types
 import Simplex.Messaging.Server.StoreLog (closeStoreLog, logCreateQueue)
 import SMPClient (testStoreLogFile, testStoreMsgsDir, testStoreMsgsDir2, testStoreMsgsFile, testStoreMsgsFile2)
@@ -109,30 +111,36 @@ deriving instance Eq (JournalState t)
 
 deriving instance Eq (SJournalType t)
 
-testNewQueueRec :: TVar ChaChaDRG -> Bool -> IO (RecipientId, QueueRec)
-testNewQueueRec g sndSecure = do
-  rId <- atomically $ EntityId <$> C.randomBytes 24 g
-  senderId <- atomically $ EntityId <$> C.randomBytes 24 g
-  (recipientKey, _) <- atomically $ C.generateAuthKeyPair C.SX25519 g
+testNewQueueRec :: TVar ChaChaDRG -> QueueMode -> IO (RecipientId, QueueRec)
+testNewQueueRec g qm = testNewQueueRecData g qm Nothing
+
+testNewQueueRecData :: TVar ChaChaDRG -> QueueMode -> Maybe (LinkId, QueueLinkData) -> IO (RecipientId, QueueRec)
+testNewQueueRecData g qm queueData = do
+  rId <- rndId
+  senderId <- rndId
+  (rKey, _) <- atomically $ C.generateAuthKeyPair C.SEd25519 g
   (k, pk) <- atomically $ C.generateKeyPair @'C.X25519 g
   let qr =
         QueueRec
-          { recipientKey,
+          { recipientKeys = [rKey],
             rcvDhSecret = C.dh' k pk,
             senderId,
             senderKey = Nothing,
-            sndSecure,
+            queueMode = Just qm,
+            queueData,
             notifier = Nothing,
             status = EntityActive,
             updatedAt = Nothing
           }
   pure (rId, qr)
+  where
+    rndId = atomically $ EntityId <$> C.randomBytes 24 g
 
 -- TODO constrain to STM stores
 testGetQueue :: MsgStoreClass s => s -> IO ()
 testGetQueue ms = do
   g <- C.newRandom
-  (rId, qr) <- testNewQueueRec g True
+  (rId, qr) <- testNewQueueRec g QMMessaging
   runRight_ $ do
     q <- ExceptT $ addQueue ms rId qr
     let write s = writeMsg ms q True =<< mkMessage s
@@ -175,7 +183,7 @@ testGetQueue ms = do
 testChangeReadJournal :: MsgStoreClass s => s -> IO ()
 testChangeReadJournal ms = do
   g <- C.newRandom
-  (rId, qr) <- testNewQueueRec g True
+  (rId, qr) <- testNewQueueRec g QMMessaging
   runRight_ $ do
     q <- ExceptT $ addQueue ms rId qr
     let write s = writeMsg ms q True =<< mkMessage s
@@ -194,8 +202,8 @@ testChangeReadJournal ms = do
 testExportImportStore :: JournalMsgStore 'QSMemory -> IO ()
 testExportImportStore ms = do
   g <- C.newRandom
-  (rId1, qr1) <- testNewQueueRec g True
-  (rId2, qr2) <- testNewQueueRec g True
+  (rId1, qr1) <- testNewQueueRec g QMMessaging
+  (rId2, qr2) <- testNewQueueRec g QMMessaging
   sl <- readWriteQueueStore True (mkQueue ms True) testStoreLogFile $ queueStore ms
   runRight_ $ do
     let write q s = writeMsg ms q True =<< mkMessage s
@@ -302,7 +310,7 @@ testQueueState ms = do
 testMessageState :: JournalMsgStore s -> IO ()
 testMessageState ms = do
   g <- C.newRandom
-  (rId, qr) <- testNewQueueRec g True
+  (rId, qr) <- testNewQueueRec g QMMessaging
   let dir = msgQueueDirectory ms rId
       statePath = msgQueueStatePath dir $ B.unpack (B64.encode $ unEntityId rId)
       write q s = writeMsg ms q True =<< mkMessage s
@@ -327,7 +335,7 @@ testMessageState ms = do
 testRemoveJournals :: JournalMsgStore s -> IO ()
 testRemoveJournals ms = do
   g <- C.newRandom
-  (rId, qr) <- testNewQueueRec g True
+  (rId, qr) <- testNewQueueRec g QMMessaging
   let dir = msgQueueDirectory ms rId
       statePath = msgQueueStatePath dir $ B.unpack (B64.encode $ unEntityId rId)
       write q s = writeMsg ms q True =<< mkMessage s
@@ -393,7 +401,7 @@ testRemoveJournals ms = do
 testRemoveQueueStateBackups :: IO ()
 testRemoveQueueStateBackups = do
   g <- C.newRandom
-  (rId, qr) <- testNewQueueRec g True
+  (rId, qr) <- testNewQueueRec g QMMessaging
 
   ms' <- newMsgStore (testJournalStoreCfg MQStoreCfg) {maxStateLines = 1, expireBackupsAfter = 0, keepMinBackups = 0}
   -- set expiration time 1 second ahead
@@ -429,7 +437,7 @@ testRemoveQueueStateBackups = do
 testExpireIdleQueues :: IO ()
 testExpireIdleQueues = do
   g <- C.newRandom
-  (rId, qr) <- testNewQueueRec g True
+  (rId, qr) <- testNewQueueRec g QMMessaging
 
   ms <- newMsgStore (testJournalStoreCfg MQStoreCfg) {idleInterval = 0}
 
@@ -462,7 +470,7 @@ testExpireIdleQueues = do
 testReadFileMissing :: JournalMsgStore s -> IO ()
 testReadFileMissing ms = do
   g <- C.newRandom
-  (rId, qr) <- testNewQueueRec g True
+  (rId, qr) <- testNewQueueRec g QMMessaging
   let write q s = writeMsg ms q True =<< mkMessage s
   q <- runRight $ do
     q <- ExceptT $ addQueue ms rId qr
@@ -486,7 +494,7 @@ testReadFileMissing ms = do
 testReadFileMissingSwitch :: JournalMsgStore s -> IO ()
 testReadFileMissingSwitch ms = do
   g <- C.newRandom
-  (rId, qr) <- testNewQueueRec g True
+  (rId, qr) <- testNewQueueRec g QMMessaging
   q <- writeMessages ms rId qr
 
   mq <- fromJust <$> readTVarIO (msgQueue q)
@@ -504,7 +512,7 @@ testReadFileMissingSwitch ms = do
 testWriteFileMissing :: JournalMsgStore s -> IO ()
 testWriteFileMissing ms = do
   g <- C.newRandom
-  (rId, qr) <- testNewQueueRec g True
+  (rId, qr) <- testNewQueueRec g QMMessaging
   q <- writeMessages ms rId qr
 
   mq <- fromJust <$> readTVarIO (msgQueue q)
@@ -527,7 +535,7 @@ testWriteFileMissing ms = do
 testReadAndWriteFilesMissing :: JournalMsgStore s -> IO ()
 testReadAndWriteFilesMissing ms = do
   g <- C.newRandom
-  (rId, qr) <- testNewQueueRec g True
+  (rId, qr) <- testNewQueueRec g QMMessaging
   q <- writeMessages ms rId qr
 
   mq <- fromJust <$> readTVarIO (msgQueue q)
diff --git a/tests/CoreTests/StoreLogTests.hs b/tests/CoreTests/StoreLogTests.hs
index 5fa36559eb..9556c67883 100644
--- a/tests/CoreTests/StoreLogTests.hs
+++ b/tests/CoreTests/StoreLogTests.hs
@@ -14,6 +14,7 @@ import CoreTests.MsgStoreTests
 import Crypto.Random (ChaChaDRG)
 import qualified Data.ByteString.Char8 as B
 import Data.Either (partitionEithers)
+import qualified Data.List.NonEmpty as L
 import qualified Data.Map.Strict as M
 import SMPClient
 import qualified Simplex.Messaging.Crypto as C
@@ -52,20 +53,46 @@ deriving instance Eq StoreLogRecord
 
 deriving instance Eq NtfCreds
 
+-- TODO [short links] test store log with queue data
 storeLogTests :: Spec
 storeLogTests =
-  forM_ [False, True] $ \sndSecure -> do
-    ((rId, qr), ntfCreds, date) <- runIO $ do
-      g <- C.newRandom
-      (,,) <$> testNewQueueRec g sndSecure <*> testNtfCreds g <*> getSystemDate
+  forM_ [QMMessaging, QMContact] $ \qm -> do
+    g <- runIO C.newRandom
+    ((rId, qr), ntfCreds, date) <- runIO $
+      (,,) <$> testNewQueueRec g qm <*> testNtfCreds g <*> getSystemDate
+    ((rId', qr'), lnkId, qd) <- runIO $ do
+      lnkId <- atomically $ EntityId <$> C.randomBytes 24 g
+      let qd = (EncDataBytes "fixed data", EncDataBytes "user data")
+      q <- testNewQueueRecData g qm (Just (lnkId, qd))
+      pure (q, lnkId, qd)
+    let pubKey = fst <$> atomically (C.generateAuthKeyPair C.SEd25519 g)
+    newKeys <- runIO $ L.fromList <$> sequence [pubKey, pubKey]
     testSMPStoreLog
-      ("SMP server store log, sndSecure = " <> show sndSecure)
+      ("SMP server store log, queueMode = " <> show qm)
       [ SLTC
           { name = "create new queue",
             saved = [CreateQueue rId qr],
             compacted = [CreateQueue rId qr],
             state = M.fromList [(rId, qr)]
           },
+        SLTC
+          { name = "create new queue with link data",
+            saved = [CreateQueue rId' qr'],
+            compacted = [CreateQueue rId' qr'],
+            state = M.fromList [(rId', qr')]
+          },          
+        SLTC
+          { name = "create new queue, add link data",
+            saved = [CreateQueue rId' qr' {queueData = Nothing}, CreateLink rId' lnkId qd],
+            compacted = [CreateQueue rId' qr'],
+            state = M.fromList [(rId', qr')]
+          },          
+        SLTC
+          { name = "create new queue with link data, delete data",
+            saved = [CreateQueue rId' qr', DeleteLink rId'],
+            compacted = [CreateQueue rId' qr' {queueData = Nothing}],
+            state = M.fromList [(rId', qr' {queueData = Nothing})]
+          },          
         SLTC
           { name = "secure queue",
             saved = [CreateQueue rId qr, SecureQueue rId testPublicAuthKey],
@@ -95,6 +122,12 @@ storeLogTests =
             saved = [CreateQueue rId qr, UpdateTime rId date],
             compacted = [CreateQueue rId qr {updatedAt = Just date}],
             state = M.fromList [(rId, qr {updatedAt = Just date})]
+          },
+        SLTC
+          { name = "update recipient keys",
+            saved = [CreateQueue rId qr, UpdateKeys rId newKeys],
+            compacted = [CreateQueue rId qr {recipientKeys = newKeys}],
+            state = M.fromList [(rId, qr {recipientKeys = newKeys})]
           }
       ]
 
diff --git a/tests/CoreTests/TRcvQueuesTests.hs b/tests/CoreTests/TRcvQueuesTests.hs
index 5b66bb8448..4098fd0f4c 100644
--- a/tests/CoreTests/TRcvQueuesTests.hs
+++ b/tests/CoreTests/TRcvQueuesTests.hs
@@ -17,7 +17,7 @@ import Simplex.Messaging.Agent.Protocol (ConnId, QueueStatus (..), UserId)
 import Simplex.Messaging.Agent.Store (DBQueueId (..), RcvQueue, StoredRcvQueue (..))
 import qualified Simplex.Messaging.Agent.TRcvQueues as RQ
 import qualified Simplex.Messaging.Crypto as C
-import Simplex.Messaging.Protocol (EntityId (..), RecipientId, SMPServer, pattern NoEntity, pattern VersionSMPC)
+import Simplex.Messaging.Protocol (EntityId (..), RecipientId, SMPServer, QueueMode (..), pattern NoEntity, pattern VersionSMPC)
 import Test.Hspec
 import UnliftIO
 
@@ -197,7 +197,8 @@ dummyRQ userId server connId rcvId =
       e2ePrivKey = "MC4CAQAwBQYDK2VuBCIEINCzbVFaCiYHoYncxNY8tSIfn0pXcIAhLBfFc0m+gOpk",
       e2eDhSecret = Nothing,
       sndId = NoEntity,
-      sndSecure = True,
+      queueMode = Just QMMessaging,
+      shortLink = Nothing,
       status = New,
       dbQueueId = DBQueueId 0,
       primary = True,
diff --git a/tests/NtfServerTests.hs b/tests/NtfServerTests.hs
index 25e2943ef6..b2e868cc20 100644
--- a/tests/NtfServerTests.hs
+++ b/tests/NtfServerTests.hs
@@ -4,6 +4,7 @@
 {-# LANGUAGE NamedFieldPuns #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE PatternSynonyms #-}
+{-# LANGUAGE RankNTypes #-}
 {-# LANGUAGE ScopedTypeVariables #-}
 {-# LANGUAGE StandaloneDeriving #-}
 {-# OPTIONS_GHC -Wno-orphans #-}
@@ -48,7 +49,8 @@ import UnliftIO.STM
 ntfServerTests :: ATransport -> Spec
 ntfServerTests t = do
   describe "Notifications server protocol syntax" $ ntfSyntaxTests t
-  describe "Notification subscriptions" $ testNotificationSubscription t
+  describe "Notification subscriptions (NKEY)" $ testNotificationSubscription t createNtfQueueNKEY
+  -- describe "Notification subscriptions (NEW with ntf creds)" $ testNotificationSubscription t createNtfQueueNEW
 
 ntfSyntaxTests :: ATransport -> Spec
 ntfSyntaxTests (ATransport t) = do
@@ -93,10 +95,9 @@ v .-> key =
   let J.Object o = v
    in U.decodeLenient . encodeUtf8 <$> JT.parseEither (J..: key) o
 
-testNotificationSubscription :: ATransport -> Spec
-testNotificationSubscription (ATransport t) =
-  -- hangs on Ubuntu 20/22
-  xit' "should create notification subscription and notify when message is received" $ do
+testNotificationSubscription :: ATransport -> CreateQueueFunc -> Spec
+testNotificationSubscription (ATransport t) createQueue =
+  it "should create notification subscription and notify when message is received" $ do
     g <- C.newRandom
     (sPub, sKey) <- atomically $ C.generateAuthKeyPair C.SEd25519 g
     (nPub, nKey) <- atomically $ C.generateAuthKeyPair C.SEd25519 g
@@ -106,8 +107,7 @@ testNotificationSubscription (ATransport t) =
     withAPNSMockServer $ \apns ->
       smpTest2' t $ \rh sh ->
         ntfTest t $ \nh -> do
-          -- create queue
-          (sId, rId, rKey, rcvDhSecret) <- createAndSecureQueue rh sPub
+          ((sId, rId, rKey, rcvDhSecret), nId, rcvNtfDhSecret) <- createQueue rh sPub nPub
           -- register and verify token
           RespNtf "1" NoEntity (NRTknId tId ntfDh) <- signSendRecvNtf nh tknKey ("1", NoEntity, TNEW $ NewNtfTkn tkn tknPub dhPub)
           APNSMockRequest {notification = APNSNotification {aps = APNSBackground _, notificationData = Just ntfData}} <-
@@ -118,12 +118,9 @@ testNotificationSubscription (ATransport t) =
               Right code = NtfRegCode <$> C.cbDecrypt dhSecret nonce verification
           RespNtf "2" _ NROk <- signSendRecvNtf nh tknKey ("2", tId, TVFY code)
           RespNtf "2a" _ (NRTkn NTActive) <- signSendRecvNtf nh tknKey ("2a", tId, TCHK)
-          -- enable queue notifications
-          (rcvNtfPubDhKey, rcvNtfPrivDhKey) <- atomically $ C.generateKeyPair g
-          Resp "3" _ (NID nId rcvNtfSrvPubDhKey) <- signSendRecv rh rKey ("3", rId, NKEY nPub rcvNtfPubDhKey)
+          -- ntf server subscribes to queue notifications
           let srv = SMPServer SMP.testHost SMP.testPort SMP.testKeyHash
               q = SMPQueueNtf srv nId
-              rcvNtfDhSecret = C.dh' rcvNtfSrvPubDhKey rcvNtfPrivDhKey
           RespNtf "4" _ (NRSubId _subId) <- signSendRecvNtf nh tknKey ("4", NoEntity, SNEW $ NewNtfSub tId q nKey)
           -- send message
           threadDelay 50000
@@ -169,3 +166,37 @@ testNotificationSubscription (ATransport t) =
               PNMessageData {smpQueue = SMPQueueNtf {smpServer = smpServer3, notifierId = notifierId3}} = L.last pnMsgs2
           smpServer3 `shouldBe` srv
           notifierId3 `shouldBe` nId
+
+type CreateQueueFunc =
+  forall c.
+  Transport c =>
+  THandleSMP c 'TClient ->
+  SndPublicAuthKey ->
+  NtfPublicAuthKey ->
+  IO ((SenderId, RecipientId, RcvPrivateAuthKey, RcvDhSecret), NotifierId, C.DhSecret 'C.X25519)
+
+createNtfQueueNKEY :: CreateQueueFunc
+createNtfQueueNKEY h sPub nPub = do
+  g <- C.newRandom
+  (sId, rId, rKey, rcvDhSecret) <- createAndSecureQueue h sPub
+  -- enable queue notifications
+  (rcvNtfPubDhKey, rcvNtfPrivDhKey) <- atomically $ C.generateKeyPair g
+  Resp "3" _ (NID nId rcvNtfSrvPubDhKey) <- signSendRecv h rKey ("3", rId, NKEY nPub rcvNtfPubDhKey)
+  let rcvNtfDhSecret = C.dh' rcvNtfSrvPubDhKey rcvNtfPrivDhKey
+  pure ((sId, rId, rKey, rcvDhSecret), nId, rcvNtfDhSecret)
+
+-- TODO [notifications]
+-- createNtfQueueNEW :: CreateQueueFunc
+-- createNtfQueueNEW h sPub nPub = do
+--   g <- C.newRandom
+--   (rPub, rKey) <- atomically $ C.generateAuthKeyPair C.SEd448 g
+--   (dhPub, dhPriv :: C.PrivateKeyX25519) <- atomically $ C.generateKeyPair g
+--   (rcvNtfPubDhKey, rcvNtfPrivDhKey) <- atomically $ C.generateKeyPair g
+--   let cmd = NEW (NewQueueReq rPub dhPub Nothing SMSubscribe (Just (QRMessaging Nothing)) (Just (NewNtfCreds nPub rcvNtfPubDhKey)))
+--   Resp "abcd" NoEntity (IDS (QIK rId sId srvDh _sndSecure _linkId (Just (ServerNtfCreds nId rcvNtfSrvPubDhKey)))) <-
+--     signSendRecv h rKey ("abcd", NoEntity, cmd)
+--   let dhShared = C.dh' srvDh dhPriv
+--   Resp "dabc" rId' OK <- signSendRecv h rKey ("dabc", rId, KEY sPub)
+--   (rId', rId) #== "same queue ID"
+--   let rcvNtfDhSecret = C.dh' rcvNtfSrvPubDhKey rcvNtfPrivDhKey
+--   pure ((sId, rId, rKey, dhShared), nId, rcvNtfDhSecret)
diff --git a/tests/SMPAgentClient.hs b/tests/SMPAgentClient.hs
index fc66f2ab1b..2903de05ca 100644
--- a/tests/SMPAgentClient.hs
+++ b/tests/SMPAgentClient.hs
@@ -20,7 +20,7 @@ import SMPClient (proxyVRangeV8, testPort)
 import Simplex.Messaging.Agent.Env.SQLite
 import Simplex.Messaging.Agent.Protocol
 import Simplex.Messaging.Agent.RetryInterval
-import Simplex.Messaging.Client (ProtocolClientConfig (..), SMPProxyFallback, SMPProxyMode, defaultNetworkConfig, defaultSMPClientConfig)
+import Simplex.Messaging.Client (ProtocolClientConfig (..), SMPProxyFallback (..), SMPProxyMode (..), defaultNetworkConfig, defaultSMPClientConfig)
 import Simplex.Messaging.Notifications.Client (defaultNTFClientConfig)
 import Simplex.Messaging.Protocol (NtfServer, ProtoServerWithAuth (..), ProtocolServer)
 import Simplex.Messaging.Transport
@@ -71,10 +71,16 @@ initAgentServers =
 initAgentServers2 :: InitialAgentServers
 initAgentServers2 = initAgentServers {smp = userServers [testSMPServer, testSMPServer2]}
 
-initAgentServersProxy :: SMPProxyMode -> SMPProxyFallback -> InitialAgentServers
-initAgentServersProxy smpProxyMode smpProxyFallback =
+initAgentServersProxy :: InitialAgentServers
+initAgentServersProxy = initAgentServersProxy_ SPMAlways SPFProhibit
+
+initAgentServersProxy_ :: SMPProxyMode -> SMPProxyFallback -> InitialAgentServers
+initAgentServersProxy_ smpProxyMode smpProxyFallback =
   initAgentServers {netCfg = (netCfg initAgentServers) {smpProxyMode, smpProxyFallback}}
 
+initAgentServersProxy2 :: InitialAgentServers
+initAgentServersProxy2 = initAgentServersProxy {smp = userServers [testSMPServer2]}
+
 agentCfg :: AgentConfig
 agentCfg =
   defaultAgentConfig
diff --git a/tests/SMPClient.hs b/tests/SMPClient.hs
index 6ee05c27b0..07dc607230 100644
--- a/tests/SMPClient.hs
+++ b/tests/SMPClient.hs
@@ -259,6 +259,11 @@ proxyCfgMS msType =
 proxyCfgJ2 :: ServerConfig
 proxyCfgJ2 = journalCfg proxyCfg testStoreLogFile2 testStoreMsgsDir2
 
+proxyCfgJ2QS :: SQSType s -> ServerConfig
+proxyCfgJ2QS = \case
+  SQSMemory -> journalCfg (proxyCfgMS $ ASType SQSMemory SMSJournal) testStoreLogFile2 testStoreMsgsDir2
+  SQSPostgres -> journalCfgDB (proxyCfgMS $ ASType SQSPostgres SMSJournal) testStoreDBOpts2 testStoreMsgsDir2
+
 proxyVRangeV8 :: VersionRangeSMP
 proxyVRangeV8 = mkVersionRange minServerSMPRelayVersion sendingProxySMPVersion
 
@@ -305,6 +310,12 @@ withSmpServer ps = withSmpServerOn ps testPort
 withSmpServerProxy :: HasCallStack => (ATransport, AStoreType) -> IO a -> IO a
 withSmpServerProxy (t, msType) = withSmpServerConfigOn t (proxyCfgMS msType) testPort . const
 
+withSmpServers2 :: HasCallStack => (ATransport, AStoreType) -> IO a -> IO a
+withSmpServers2 ps@(t, ASType qs _ms) = withSmpServer ps . withSmpServerConfigOn t (cfgJ2QS qs) testPort2 . const
+
+withSmpServersProxy2 :: HasCallStack => (ATransport, AStoreType) -> IO a -> IO a
+withSmpServersProxy2 ps@(t, ASType qs _ms) = withSmpServerProxy ps . withSmpServerConfigOn t (proxyCfgJ2QS qs) testPort2 . const
+
 runSmpTest :: forall c a. (HasCallStack, Transport c) => AStoreType -> (HasCallStack => THandleSMP c 'TClient -> IO a) -> IO a
 runSmpTest msType test = withSmpServerConfigOn (transport @c) (cfgMS msType) testPort $ \_ -> testSMPClient test
 
diff --git a/tests/SMPProxyTests.hs b/tests/SMPProxyTests.hs
index 4be81aedc1..7ef66544ef 100644
--- a/tests/SMPProxyTests.hs
+++ b/tests/SMPProxyTests.hs
@@ -36,7 +36,7 @@ import Simplex.Messaging.Client
 import qualified Simplex.Messaging.Crypto as C
 import Simplex.Messaging.Crypto.Ratchet (pattern PQSupportOn)
 import qualified Simplex.Messaging.Crypto.Ratchet as CR
-import Simplex.Messaging.Protocol (EncRcvMsgBody (..), MsgBody, RcvMessage (..), SubscriptionMode (..), maxMessageLength, noMsgFlags, pattern NoEntity)
+import Simplex.Messaging.Protocol (EncRcvMsgBody (..), MsgBody, QueueReqData (..), RcvMessage (..), SubscriptionMode (..), maxMessageLength, noMsgFlags, pattern NoEntity)
 import qualified Simplex.Messaging.Protocol as SMP
 import Simplex.Messaging.Server.Env.STM (AStoreType (..), ServerConfig (..))
 import Simplex.Messaging.Server.MsgStore.Types (SQSType (..))
@@ -177,7 +177,7 @@ deliverMessagesViaProxy proxyServ relayServ alg unsecuredMsgs securedMsgs = do
   -- prepare receiving queue
   (rPub, rPriv) <- atomically $ C.generateAuthKeyPair alg g
   (rdhPub, rdhPriv :: C.PrivateKeyX25519) <- atomically $ C.generateKeyPair g
-  SMP.QIK {rcvId, sndId, rcvPublicDhKey = srvDh} <- runExceptT' $ createSMPQueue rc (rPub, rPriv) rdhPub (Just "correct") SMSubscribe False
+  SMP.QIK {rcvId, sndId, rcvPublicDhKey = srvDh} <- runExceptT' $ createSMPQueue rc Nothing (rPub, rPriv) rdhPub (Just "correct") SMSubscribe (QRMessaging Nothing)
   let dec = decryptMsgV3 $ C.dh' srvDh rdhPriv
   -- get proxy session
   sess0 <- runExceptT' $ connectSMPProxiedRelay pc relayServ (Just "correct")
@@ -224,7 +224,7 @@ agentDeliverMessageViaProxy :: (C.AlgorithmI a, C.AuthAlgorithm a) => (NonEmpty
 agentDeliverMessageViaProxy aTestCfg@(aSrvs, _, aViaProxy) bTestCfg@(bSrvs, _, bViaProxy) alg msg1 msg2 baseId =
   withAgent 1 aCfg (servers aTestCfg) testDB $ \alice ->
     withAgent 2 aCfg (servers bTestCfg) testDB2 $ \bob -> runRight_ $ do
-      (bobId, qInfo) <- A.createConnection alice 1 True SCMInvitation Nothing (CR.IKNoPQ PQSupportOn) SMSubscribe
+      (bobId, CCLink qInfo Nothing) <- A.createConnection alice 1 True SCMInvitation Nothing Nothing (CR.IKNoPQ PQSupportOn) SMSubscribe
       aliceId <- A.prepareConnectionToJoin bob 1 True qInfo PQSupportOn
       sqSecured <- A.joinConnection bob 1 aliceId True qInfo "bob's connInfo" PQSupportOn SMSubscribe
       liftIO $ sqSecured `shouldBe` True
@@ -257,7 +257,7 @@ agentDeliverMessageViaProxy aTestCfg@(aSrvs, _, aViaProxy) bTestCfg@(bSrvs, _, b
   where
     msgId = subtract baseId . fst
     aCfg = agentCfg {sndAuthAlg = C.AuthAlg alg, rcvAuthAlg = C.AuthAlg alg}
-    servers (srvs, smpProxyMode, _) = (initAgentServersProxy smpProxyMode SPFAllow) {smp = userServers srvs}
+    servers (srvs, smpProxyMode, _) = (initAgentServersProxy_ smpProxyMode SPFAllow) {smp = userServers srvs}
 
 agentDeliverMessagesViaProxyConc :: [NonEmpty SMPServer] -> [MsgBody] -> IO ()
 agentDeliverMessagesViaProxyConc agentServers msgs =
@@ -280,7 +280,7 @@ agentDeliverMessagesViaProxyConc agentServers msgs =
     -- agent connections have to be set up in advance
     -- otherwise the CONF messages would get mixed with MSG
     prePair alice bob = do
-      (bobId, qInfo) <- runExceptT' $ A.createConnection alice 1 True SCMInvitation Nothing (CR.IKNoPQ PQSupportOn) SMSubscribe
+      (bobId, CCLink qInfo Nothing) <- runExceptT' $ A.createConnection alice 1 True SCMInvitation Nothing Nothing (CR.IKNoPQ PQSupportOn) SMSubscribe
       aliceId <- runExceptT' $ A.prepareConnectionToJoin bob 1 True qInfo PQSupportOn
       sqSecured <- runExceptT' $ A.joinConnection bob 1 aliceId True qInfo "bob's connInfo" PQSupportOn SMSubscribe
       liftIO $ sqSecured `shouldBe` True
@@ -324,19 +324,19 @@ agentDeliverMessagesViaProxyConc agentServers msgs =
       logDebug "run finished"
     pqEnc = CR.PQEncOn
     aCfg = agentCfg {sndAuthAlg = C.AuthAlg C.SEd448, rcvAuthAlg = C.AuthAlg C.SEd448}
-    servers srvs = (initAgentServersProxy SPMAlways SPFAllow) {smp = userServers srvs}
+    servers srvs = (initAgentServersProxy_ SPMAlways SPFAllow) {smp = userServers srvs}
 
 agentViaProxyVersionError :: IO ()
 agentViaProxyVersionError =
   withAgent 1 agentCfg (servers [SMPServer testHost testPort testKeyHash]) testDB $ \alice -> do
     Left (A.BROKER _ (TRANSPORT TEVersion)) <-
       withAgent 2 agentCfg (servers [SMPServer testHost2 testPort2 testKeyHash]) testDB2 $ \bob -> runExceptT $ do
-        (_bobId, qInfo) <- A.createConnection alice 1 True SCMInvitation Nothing (CR.IKNoPQ PQSupportOn) SMSubscribe
+        (_bobId, CCLink qInfo Nothing) <- A.createConnection alice 1 True SCMInvitation Nothing Nothing (CR.IKNoPQ PQSupportOn) SMSubscribe
         aliceId <- A.prepareConnectionToJoin bob 1 True qInfo PQSupportOn
         A.joinConnection bob 1 aliceId True qInfo "bob's connInfo" PQSupportOn SMSubscribe
     pure ()
   where
-    servers srvs = (initAgentServersProxy SPMUnknown SPFProhibit) {smp = userServers srvs}
+    servers srvs = (initAgentServersProxy_ SPMUnknown SPFProhibit) {smp = userServers srvs}
 
 agentViaProxyRetryOffline :: IO ()
 agentViaProxyRetryOffline = do
@@ -351,7 +351,7 @@ agentViaProxyRetryOffline = do
       let pqEnc = CR.PQEncOn
       withServer $ \_ -> do
         (aliceId, bobId) <- withServer2 $ \_ -> runRight $ do
-          (bobId, qInfo) <- A.createConnection alice 1 True SCMInvitation Nothing (CR.IKNoPQ PQSupportOn) SMSubscribe
+          (bobId, CCLink qInfo Nothing) <- A.createConnection alice 1 True SCMInvitation Nothing Nothing (CR.IKNoPQ PQSupportOn) SMSubscribe
           aliceId <- A.prepareConnectionToJoin bob 1 True qInfo PQSupportOn
           sqSecured <- A.joinConnection bob 1 aliceId True qInfo "bob's connInfo" PQSupportOn SMSubscribe
           liftIO $ sqSecured `shouldBe` True
@@ -408,7 +408,7 @@ agentViaProxyRetryOffline = do
     aCfg = agentCfg {messageRetryInterval = fastMessageRetryInterval}
     baseId = 1
     msgId = subtract baseId . fst
-    servers srv = (initAgentServersProxy SPMAlways SPFProhibit) {smp = userServers [srv]}
+    servers srv = initAgentServersProxy {smp = userServers [srv]}
 
 agentViaProxyRetryNoSession :: IO ()
 agentViaProxyRetryNoSession = do
@@ -428,7 +428,7 @@ agentViaProxyRetryNoSession = do
           pure ()
   where
     withServer2 = withSmpServerConfigOn (transport @TLS) proxyCfgJ2 testPort2
-    servers srv = (initAgentServersProxy SPMAlways SPFProhibit) {smp = userServers [srv]}
+    servers srv = initAgentServersProxy {smp = userServers [srv]}
 
 testNoProxy :: AStoreType -> IO ()
 testNoProxy msType = do
diff --git a/tests/ServerTests.hs b/tests/ServerTests.hs
index 8255b898ae..df633b570b 100644
--- a/tests/ServerTests.hs
+++ b/tests/ServerTests.hs
@@ -60,6 +60,8 @@ serverTests = do
     describe "NEW and SKEY commands" $ do
       testCreateSndSecure
       testSndSecureProhibited
+    describe "RKEY command to add additional recipient keys" $
+      testCreateUpdateKeys
     describe "NEW, OFF and DEL commands, SEND messages" testCreateDelete
     describe "Stress test" stressTest
     describe "allowNewQueues setting" testAllowNewQueues
@@ -80,12 +82,18 @@ serverTests = do
     testMsgExpireOnInterval
     testMsgNOTExpireOnInterval
   describe "Blocking queues" $ testBlockMessageQueue
+  describe "Short links" $ do
+    testInvQueueLinkData
+    testContactQueueLinkData
 
 pattern Resp :: CorrId -> QueueId -> BrokerMsg -> SignedTransmission ErrorType BrokerMsg
 pattern Resp corrId queueId command <- (_, _, (corrId, queueId, Right command))
 
+pattern New :: RcvPublicAuthKey -> RcvPublicDhKey -> Command 'Recipient
+pattern New rPub dhPub = NEW (NewQueueReq rPub dhPub Nothing SMSubscribe (Just (QRMessaging Nothing)))
+
 pattern Ids :: RecipientId -> SenderId -> RcvPublicDhKey -> BrokerMsg
-pattern Ids rId sId srvDh <- IDS (QIK rId sId srvDh _sndSecure)
+pattern Ids rId sId srvDh <- IDS (QIK rId sId srvDh _sndSecure _linkId)
 
 pattern Msg :: MsgId -> MsgBody -> BrokerMsg
 pattern Msg msgId body <- MSG RcvMessage {msgId, msgBody = EncRcvMsgBody body}
@@ -146,7 +154,7 @@ testCreateSecure =
       g <- C.newRandom
       (rPub, rKey) <- atomically $ C.generateAuthKeyPair C.SEd448 g
       (dhPub, dhPriv :: C.PrivateKeyX25519) <- atomically $ C.generateKeyPair g
-      Resp "abcd" rId1 (Ids rId sId srvDh) <- signSendRecv r rKey ("abcd", NoEntity, NEW rPub dhPub Nothing SMSubscribe False)
+      Resp "abcd" rId1 (Ids rId sId srvDh) <- signSendRecv r rKey ("abcd", NoEntity, New rPub dhPub)
       let dec = decryptMsgV3 $ C.dh' srvDh dhPriv
       (rId1, NoEntity) #== "creates queue"
 
@@ -211,7 +219,7 @@ testCreateSndSecure =
       g <- C.newRandom
       (rPub, rKey) <- atomically $ C.generateAuthKeyPair C.SEd448 g
       (dhPub, dhPriv :: C.PrivateKeyX25519) <- atomically $ C.generateKeyPair g
-      Resp "abcd" rId1 (Ids rId sId srvDh) <- signSendRecv r rKey ("abcd", NoEntity, NEW rPub dhPub Nothing SMSubscribe True)
+      Resp "abcd" rId1 (Ids rId sId srvDh) <- signSendRecv r rKey ("abcd", NoEntity, New rPub dhPub)
       let dec = decryptMsgV3 $ C.dh' srvDh dhPriv
       (rId1, NoEntity) #== "creates queue"
 
@@ -225,8 +233,8 @@ testCreateSndSecure =
       Resp "dabc" sId2 OK <- signSendRecv s sKey ("dabc", sId, SKEY sPub)
       (sId2, sId) #== "secures queue, same queue ID in response"
 
-      (sPub', _) <- atomically $ C.generateAuthKeyPair C.SEd448 g
-      Resp "abcd" _ err4 <- signSendRecv s sKey ("abcd", sId, SKEY sPub')
+      (sPub', sKey') <- atomically $ C.generateAuthKeyPair C.SEd448 g
+      Resp "abcd" _ err4 <- signSendRecv s sKey' ("abcd", sId, SKEY sPub')
       (err4, ERR AUTH) #== "rejects if secured with different key"
       Resp "abcd" _ OK <- signSendRecv s sKey ("abcd", sId, SKEY sPub)
 
@@ -258,7 +266,7 @@ testSndSecureProhibited =
       g <- C.newRandom
       (rPub, rKey) <- atomically $ C.generateAuthKeyPair C.SEd448 g
       (dhPub, _dhPriv :: C.PrivateKeyX25519) <- atomically $ C.generateKeyPair g
-      Resp "abcd" rId1 (Ids _rId sId _srvDh) <- signSendRecv r rKey ("abcd", NoEntity, NEW rPub dhPub Nothing SMSubscribe False)
+      Resp "abcd" rId1 (Ids _rId sId _srvDh) <- signSendRecv r rKey ("abcd", NoEntity, NEW (NewQueueReq rPub dhPub Nothing SMSubscribe (Just (QRContact Nothing))))
       (rId1, NoEntity) #== "creates queue"
 
       (sPub, sKey) <- atomically $ C.generateAuthKeyPair C.SEd448 g
@@ -266,6 +274,38 @@ testSndSecureProhibited =
       (sId2, sId) #== "secures queue, same queue ID in response"
       (err, ERR AUTH) #== "rejects SKEY when not allowed in NEW command"
 
+testCreateUpdateKeys :: SpecWith (ATransport, AStoreType)
+testCreateUpdateKeys =
+  it "should create (NEW) and updated recipient keys (RKEY)" $ \(ATransport t, msType) ->
+    smpTest t msType $ \h -> do
+      g <- C.newRandom
+      (rPub, rKey) <- atomically $ C.generateAuthKeyPair C.SEd25519 g
+      (dhPub, _dhPriv :: C.PrivateKeyX25519) <- atomically $ C.generateKeyPair g
+      Resp "1" NoEntity (Ids rId _sId _srvDh) <- signSendRecv h rKey ("1", NoEntity, NEW (NewQueueReq rPub dhPub Nothing SMSubscribe (Just (QRContact Nothing))))
+      (rPub', rKey') <- atomically $ C.generateAuthKeyPair C.SEd25519 g
+      Resp "2" rId1 OK <- signSendRecv h rKey ("2", rId, RKEY [rPub, rPub'])
+      rId1 `shouldBe` rId
+      -- old key still works
+      Resp "3" rId2 (INFO _) <- signSendRecv h rKey ("3", rId, QUE)
+      rId2 `shouldBe` rId
+      -- new key works too
+      Resp "4" _ (INFO _) <- signSendRecv h rKey ("4", rId, QUE)
+      -- remove old key, only keep the new one
+      Resp "5" _ OK <- signSendRecv h rKey' ("5", rId, RKEY [rPub'])
+      -- old key no longer works
+      Resp "6" _ (ERR AUTH) <- signSendRecv h rKey ("6", rId, QUE)
+      -- add old key back
+      Resp "7" _ OK <- signSendRecv h rKey' ("7", rId, RKEY [rPub, rPub'])
+      -- old key works again
+      Resp "8" _ (INFO _) <- signSendRecv h rKey ("8", rId, QUE)
+      -- key can remove itself
+      Resp "9" _ OK <- signSendRecv h rKey ("9", rId, RKEY [rPub'])
+      -- old key does not work
+      Resp "10" _ (ERR AUTH) <- signSendRecv h rKey ("10", rId, QUE)
+      -- new key works
+      Resp "11" _ (INFO _) <- signSendRecv h rKey' ("11", rId, QUE)
+      pure ()
+
 testCreateDelete :: SpecWith (ATransport, AStoreType)
 testCreateDelete =
   it "should create (NEW), suspend (OFF) and delete (DEL) queue" $ \(ATransport t, msType) ->
@@ -273,7 +313,7 @@ testCreateDelete =
       g <- C.newRandom
       (rPub, rKey) <- atomically $ C.generateAuthKeyPair C.SEd25519 g
       (dhPub, dhPriv :: C.PrivateKeyX25519) <- atomically $ C.generateKeyPair g
-      Resp "abcd" rId1 (Ids rId sId srvDh) <- signSendRecv rh rKey ("abcd", NoEntity, NEW rPub dhPub Nothing SMSubscribe False)
+      Resp "abcd" rId1 (Ids rId sId srvDh) <- signSendRecv rh rKey ("abcd", NoEntity, New rPub dhPub)
       let dec = decryptMsgV3 $ C.dh' srvDh dhPriv
       (rId1, NoEntity) #== "creates queue"
 
@@ -345,7 +385,7 @@ stressTest =
       (rPub, rKey) <- atomically $ C.generateAuthKeyPair C.SEd25519 g
       (dhPub, _ :: C.PrivateKeyX25519) <- atomically $ C.generateKeyPair g
       rIds <- forM ([1 .. 50] :: [Int]) . const $ do
-        Resp "" NoEntity (Ids rId _ _) <- signSendRecv h1 rKey ("", NoEntity, NEW rPub dhPub Nothing SMSubscribe False)
+        Resp "" NoEntity (Ids rId _ _) <- signSendRecv h1 rKey ("", NoEntity, New rPub dhPub)
         pure rId
       let subscribeQueues h = forM_ rIds $ \rId -> do
             Resp "" rId' OK <- signSendRecv h rKey ("", rId, SUB)
@@ -363,7 +403,7 @@ testAllowNewQueues =
         g <- C.newRandom
         (rPub, rKey) <- atomically $ C.generateAuthKeyPair C.SEd448 g
         (dhPub, _ :: C.PrivateKeyX25519) <- atomically $ C.generateKeyPair g
-        Resp "abcd" NoEntity (ERR AUTH) <- signSendRecv h rKey ("abcd", NoEntity, NEW rPub dhPub Nothing SMSubscribe False)
+        Resp "abcd" NoEntity (ERR AUTH) <- signSendRecv h rKey ("abcd", NoEntity, New rPub dhPub)
         pure ()
 
 testDuplex :: SpecWith (ATransport, AStoreType)
@@ -373,7 +413,7 @@ testDuplex =
       g <- C.newRandom
       (arPub, arKey) <- atomically $ C.generateAuthKeyPair C.SEd448 g
       (aDhPub, aDhPriv :: C.PrivateKeyX25519) <- atomically $ C.generateKeyPair g
-      Resp "abcd" _ (Ids aRcv aSnd aSrvDh) <- signSendRecv alice arKey ("abcd", NoEntity, NEW arPub aDhPub Nothing SMSubscribe False)
+      Resp "abcd" _ (Ids aRcv aSnd aSrvDh) <- signSendRecv alice arKey ("abcd", NoEntity, New arPub aDhPub)
       let aDec = decryptMsgV3 $ C.dh' aSrvDh aDhPriv
       -- aSnd ID is passed to Bob out-of-band
 
@@ -389,7 +429,7 @@ testDuplex =
 
       (brPub, brKey) <- atomically $ C.generateAuthKeyPair C.SEd448 g
       (bDhPub, bDhPriv :: C.PrivateKeyX25519) <- atomically $ C.generateKeyPair g
-      Resp "abcd" _ (Ids bRcv bSnd bSrvDh) <- signSendRecv bob brKey ("abcd", NoEntity, NEW brPub bDhPub Nothing SMSubscribe False)
+      Resp "abcd" _ (Ids bRcv bSnd bSrvDh) <- signSendRecv bob brKey ("abcd", NoEntity, New brPub bDhPub)
       let bDec = decryptMsgV3 $ C.dh' bSrvDh bDhPriv
       Resp "bcda" _ OK <- signSendRecv bob bsKey ("bcda", aSnd, _SEND $ "reply_id " <> encode (unEntityId bSnd))
       -- "reply_id ..." is ad-hoc, not a part of SMP protocol
@@ -428,7 +468,7 @@ testSwitchSub =
       g <- C.newRandom
       (rPub, rKey) <- atomically $ C.generateAuthKeyPair C.SEd448 g
       (dhPub, dhPriv :: C.PrivateKeyX25519) <- atomically $ C.generateKeyPair g
-      Resp "abcd" _ (Ids rId sId srvDh) <- signSendRecv rh1 rKey ("abcd", NoEntity, NEW rPub dhPub Nothing SMSubscribe False)
+      Resp "abcd" _ (Ids rId sId srvDh) <- signSendRecv rh1 rKey ("abcd", NoEntity, New rPub dhPub)
       let dec = decryptMsgV3 $ C.dh' srvDh dhPriv
       Resp "bcda" _ ok1 <- sendRecv sh ("", "bcda", sId, _SEND "test1")
       (ok1, OK) #== "sent test message 1"
@@ -849,7 +889,7 @@ createAndSecureQueue h sPub = do
   g <- C.newRandom
   (rPub, rKey) <- atomically $ C.generateAuthKeyPair C.SEd448 g
   (dhPub, dhPriv :: C.PrivateKeyX25519) <- atomically $ C.generateKeyPair g
-  Resp "abcd" NoEntity (Ids rId sId srvDh) <- signSendRecv h rKey ("abcd", NoEntity, NEW rPub dhPub Nothing SMSubscribe False)
+  Resp "abcd" NoEntity (Ids rId sId srvDh) <- signSendRecv h rKey ("abcd", NoEntity, New rPub dhPub)
   let dhShared = C.dh' srvDh dhPriv
   Resp "dabc" rId' OK <- signSendRecv h rKey ("dabc", rId, KEY sPub)
   (rId', rId) #== "same queue ID"
@@ -884,7 +924,7 @@ testTiming =
       g <- C.newRandom
       (rPub, rKey) <- atomically $ C.generateAuthKeyPair goodKeyAlg g
       (dhPub, dhPriv :: C.PrivateKeyX25519) <- atomically $ C.generateKeyPair g
-      Resp "abcd" NoEntity (Ids rId sId srvDh) <- signSendRecv rh rKey ("abcd", NoEntity, NEW rPub dhPub Nothing SMSubscribe False)
+      Resp "abcd" NoEntity (Ids rId sId srvDh) <- signSendRecv rh rKey ("abcd", NoEntity, New rPub dhPub)
       let dec = decryptMsgV3 $ C.dh' srvDh dhPriv
       Resp "cdab" _ OK <- signSendRecv rh rKey ("cdab", rId, SUB)
 
@@ -1032,7 +1072,7 @@ testBlockMessageQueue =
     (rId, sId) <- withSmpServerStoreLogOn ps testPort $ runTest t $ \h -> do
       (rPub, rKey) <- atomically $ C.generateAuthKeyPair C.SEd448 g
       (dhPub, _dhPriv :: C.PrivateKeyX25519) <- atomically $ C.generateKeyPair g
-      Resp "abcd" rId1 (Ids rId sId _srvDh) <- signSendRecv h rKey ("abcd", NoEntity, NEW rPub dhPub Nothing SMSubscribe True)
+      Resp "abcd" rId1 (Ids rId sId _srvDh) <- signSendRecv h rKey ("abcd", NoEntity, New rPub dhPub)
       (rId1, NoEntity) #== "creates queue"
       pure (rId, sId)
 
@@ -1050,6 +1090,119 @@ testBlockMessageQueue =
       killThread server
       pure a
 
+testInvQueueLinkData :: SpecWith (ATransport, AStoreType)
+testInvQueueLinkData = 
+  it "create and access queue short link data for 1-time invitation"  $ \(ATransport t, msType) ->
+    smpTest2 t msType $ \r s -> do
+      g <- C.newRandom
+      (rPub, rKey) <- atomically $ C.generateAuthKeyPair C.SEd25519 g
+      (dhPub, _dhPriv :: C.PrivateKeyX25519) <- atomically $ C.generateKeyPair g
+      C.CbNonce corrId <- atomically $ C.randomCbNonce g
+      let sId = EntityId $ B.take 24 $ C.sha3_384 corrId
+          ld = (EncDataBytes "fixed data", EncDataBytes "user data")
+          qrd = QRMessaging $ Just (sId, ld)
+      -- sender ID must be derived from corrId
+      Resp "1" NoEntity (ERR (CMD PROHIBITED)) <-
+        signSendRecv r rKey ("1", NoEntity, NEW (NewQueueReq rPub dhPub Nothing SMSubscribe (Just qrd)))
+      Resp corrId' NoEntity (IDS (QIK rId sId' _srvDh (Just QMMessaging) (Just lnkId))) <-
+        signSendRecv r rKey (corrId, NoEntity, NEW (NewQueueReq rPub dhPub Nothing SMSubscribe (Just qrd)))
+      (sId', sId) #== "should return the same sender ID"
+      corrId' `shouldBe` CorrId corrId
+      -- can't read link data with LGET
+      Resp "2" lnkId' (ERR AUTH) <- sendRecv s ("", "2", lnkId, LGET)
+      lnkId' `shouldBe` lnkId
+
+      (sPub, sKey) <- atomically $ C.generateAuthKeyPair C.SEd25519 g
+
+      Resp "3a" _ err2 <- sendRecv s ("", "3a", lnkId, LKEY sPub)
+      (err2, ERR (CMD NO_AUTH)) #== "rejects LKEY without signature"
+
+      Resp "3b" _ err2' <- sendRecv s (sampleSig, "3b", lnkId, LKEY sPub)
+      (err2', ERR AUTH) #== "rejects LKEY with wrong signature"
+
+      Resp "4" _ err3 <- signSendRecv s sKey ("4", rId, LKEY sPub)
+      (err3, ERR AUTH) #== "rejects LKEY with recipients's ID"
+
+      Resp "5" lnkId2 (LNK sId2 ld') <- signSendRecv s sKey ("5", lnkId, LKEY sPub)
+      (lnkId2, lnkId) #== "secures queue and returns link data, same link ID in response"
+      (sId2, sId) #== "same sender ID in response"
+      (ld', ld) #== "returns stored data"
+
+      (sPub', sKey') <- atomically $ C.generateAuthKeyPair C.SEd25519 g
+      Resp "6" _ err4 <- signSendRecv s sKey' ("6", lnkId, LKEY sPub')
+      (err4, ERR AUTH) #== "rejects if secured with different key"
+
+      Resp "7" _ (LNK sId3 ld2) <- signSendRecv s sKey ("7", lnkId, LKEY sPub)
+      sId3 `shouldBe` sId
+      ld2 `shouldBe` ld
+
+      let newLD = (EncDataBytes "fixed data", EncDataBytes "updated user data")
+      Resp "8" rId' (ERR AUTH) <- signSendRecv r rKey ("8", rId, LSET lnkId newLD)
+      rId' `shouldBe` rId
+
+      Resp "9" rId2 (ERR AUTH) <- signSendRecv r rKey ("9", rId, LDEL)
+      rId2 `shouldBe` rId
+
+testContactQueueLinkData :: SpecWith (ATransport, AStoreType)
+testContactQueueLinkData = 
+  it "create and access queue short link data for contact address"  $ \(ATransport t, msType) ->
+    smpTest2 t msType $ \r s -> do
+      g <- C.newRandom
+      (rPub, rKey) <- atomically $ C.generateAuthKeyPair C.SEd25519 g
+      (dhPub, _dhPriv :: C.PrivateKeyX25519) <- atomically $ C.generateKeyPair g
+      C.CbNonce corrId <- atomically $ C.randomCbNonce g
+      lnkId <- EntityId <$> atomically (C.randomBytes 24 g)
+      let sId = EntityId $ B.take 24 $ C.sha3_384 corrId
+          ld = (EncDataBytes "fixed data", EncDataBytes "user data")
+          qrd = QRContact $ Just (lnkId, (sId, ld))
+      -- sender ID must be derived from corrId
+      Resp "1" NoEntity (ERR (CMD PROHIBITED)) <-
+        signSendRecv r rKey ("1", NoEntity, NEW (NewQueueReq rPub dhPub Nothing SMSubscribe (Just qrd)))
+      Resp corrId' NoEntity (IDS (QIK rId sId' _srvDh (Just QMContact) (Just lnkId'))) <-
+        signSendRecv r rKey (corrId, NoEntity, NEW (NewQueueReq rPub dhPub Nothing SMSubscribe (Just qrd)))
+      (lnkId', lnkId) #== "should return the same link ID"
+      (sId', sId) #== "should return the same sender ID"
+      corrId' `shouldBe` CorrId corrId
+      -- can't secure queue and read link data with LKEY
+      (sPub, sKey) <- atomically $ C.generateAuthKeyPair C.SEd25519 g
+      Resp "2" _ (ERR AUTH) <- signSendRecv s sKey ("2", lnkId, LKEY sPub)
+
+      Resp "3" _ err2 <- sendRecv s (sampleSig, "3", lnkId, LGET)
+      (err2, ERR (CMD HAS_AUTH)) #== "rejects LGET with signature"
+
+      Resp "4" _ err3 <- sendRecv s ("", "4", rId, LGET)
+      (err3, ERR AUTH) #== "rejects LGET with recipients's ID"
+
+      Resp "5" lnkId2 (LNK sId2 ld') <- sendRecv s ("", "5", lnkId, LGET)
+      (lnkId2, lnkId) #== "returns link data, same link ID in response"
+      (sId2, sId) #== "same sender ID in response"
+      (ld', ld) #== "returns stored data"
+
+      Resp "6" _ (LNK sId3 ld2) <- sendRecv s ("", "6", lnkId, LGET)
+      sId3 `shouldBe` sId
+      ld2 `shouldBe` ld
+
+      let newLD = (EncDataBytes "fixed data", EncDataBytes "updated user data")
+      Resp "7" rId' OK <- signSendRecv r rKey ("7", rId, LSET lnkId newLD)
+      rId' `shouldBe` rId
+
+      Resp "8" _ (LNK sId4 ld3) <- sendRecv s ("", "8", lnkId, LGET)
+      sId4 `shouldBe` sId
+      ld3 `shouldBe` newLD
+
+      badLnkId <- EntityId <$> atomically (C.randomBytes 24 g)
+      Resp "9" _ (ERR AUTH) <- signSendRecv r rKey ("9", rId, LSET badLnkId newLD)
+
+      let badLD = (EncDataBytes "changed fixed data", EncDataBytes "updated user data 2")
+      Resp "10" _ (ERR AUTH) <- signSendRecv r rKey ("10", rId, LSET lnkId badLD)
+
+      Resp "11" rId2 OK <- signSendRecv r rKey ("11", rId, LDEL)
+      rId2 `shouldBe` rId
+      Resp "11a" _ OK <- signSendRecv r rKey ("11a", rId, LDEL)
+
+      Resp "12" lnkId3 (ERR AUTH) <- sendRecv s ("", "12", lnkId, LGET)
+      lnkId3 `shouldBe` lnkId
+
 samplePubKey :: C.APublicVerifyKey
 samplePubKey = C.APublicVerifyKey C.SEd25519 "MCowBQYDK2VwAyEAfAOflyvbJv1fszgzkQ6buiZJVgSpQWsucXq7U6zjMgY="
 
@@ -1075,8 +1228,8 @@ serverSyntaxTests (ATransport t) = do
   describe "NEW" $ do
     it "no parameters" $ (sampleSig, "bcda", "", NEW_) >#> ("", "bcda", "", ERR $ CMD SYNTAX)
     it "many parameters" $ (sampleSig, "cdab", "", (NEW_, ' ', ('\x01', 'A'), samplePubKey, sampleDhPubKey)) >#> ("", "cdab", "", ERR $ CMD SYNTAX)
-    it "no signature" $ ("", "dabc", "", (NEW_, ' ', samplePubKey, sampleDhPubKey, '0', SMSubscribe, False)) >#> ("", "dabc", "", ERR $ CMD NO_AUTH)
-    it "queue ID" $ (sampleSig, "abcd", "12345678", (NEW_, ' ', samplePubKey, sampleDhPubKey, '0', SMSubscribe, False)) >#> ("", "abcd", "12345678", ERR $ CMD HAS_AUTH)
+    it "no signature" $ ("", "dabc", "", ((NEW_, ' ', samplePubKey, sampleDhPubKey), ('0', SMSubscribe, Just (QRMessaging Nothing)))) >#> ("", "dabc", "", ERR $ CMD NO_AUTH)
+    it "queue ID" $ (sampleSig, "abcd", "12345678", ((NEW_, ' ', samplePubKey, sampleDhPubKey), ('0', SMSubscribe, Just (QRMessaging Nothing)))) >#> ("", "abcd", "12345678", ERR $ CMD HAS_AUTH)
   describe "KEY" $ do
     it "valid syntax" $ (sampleSig, "bcda", "12345678", (KEY_, ' ', samplePubKey)) >#> ("", "bcda", "12345678", ERR AUTH)
     it "no parameters" $ (sampleSig, "cdab", "12345678", KEY_) >#> ("", "cdab", "12345678", ERR $ CMD SYNTAX)
diff --git a/tests/ServerTests/SchemaDump.hs b/tests/ServerTests/SchemaDump.hs
new file mode 100644
index 0000000000..e3ffdb5cba
--- /dev/null
+++ b/tests/ServerTests/SchemaDump.hs
@@ -0,0 +1,98 @@
+{-# LANGUAGE NamedFieldPuns #-}
+{-# LANGUAGE OverloadedStrings #-}
+
+module ServerTests.SchemaDump where
+
+import Control.Concurrent (threadDelay)
+import Control.DeepSeq
+import Control.Monad (unless, void)
+import qualified Data.ByteString.Char8 as B
+import Data.List (dropWhileEnd)
+import Data.Maybe (fromJust, isJust)
+import SMPClient
+import Simplex.Messaging.Agent.Store.Postgres (closeDBStore, createDBStore)
+import Simplex.Messaging.Agent.Store.Postgres.Common (DBOpts (..))
+import qualified Simplex.Messaging.Agent.Store.Postgres.Migrations as Migrations
+import Simplex.Messaging.Agent.Store.Shared (Migration (..), MigrationConfirmation (..), MigrationsToRun (..), toDownMigration)
+import Simplex.Messaging.Server.QueueStore.Postgres.Migrations (serverMigrations)
+import Simplex.Messaging.Util (ifM)
+import System.Directory (doesFileExist, removeFile)
+import System.Environment (lookupEnv)
+import System.Process (readCreateProcess, readCreateProcessWithExitCode, shell)
+import Test.Hspec
+
+testDBSchema :: B.ByteString
+testDBSchema = "smp_server"
+
+serverSchemaPath :: FilePath
+serverSchemaPath = "src/Simplex/Messaging/Server/QueueStore/Postgres/server_schema.sql"
+
+testSchemaPath :: FilePath
+testSchemaPath = "tests/tmp/test_server_schema.sql"
+
+testServerDBOpts :: DBOpts
+testServerDBOpts = 
+  DBOpts
+    { connstr = testServerDBConnstr,
+      schema = testDBSchema,
+      poolSize = 3,
+      createSchema = True
+    }
+
+serverSchemaDumpTest :: Spec
+serverSchemaDumpTest = do
+  it "verify and overwrite schema dump" testVerifySchemaDump
+  it "verify schema down migrations" testSchemaMigrations
+
+testVerifySchemaDump :: IO ()
+testVerifySchemaDump = do
+  savedSchema <- ifM (doesFileExist serverSchemaPath) (readFile serverSchemaPath) (pure "")
+  savedSchema `deepseq` pure ()
+  void $ createDBStore testServerDBOpts serverMigrations MCConsole
+  getSchema serverSchemaPath `shouldReturn` savedSchema
+
+testSchemaMigrations :: IO ()
+testSchemaMigrations = do
+  let noDownMigrations = dropWhileEnd (\Migration {down} -> isJust down) serverMigrations
+  Right st <- createDBStore testServerDBOpts noDownMigrations MCError
+  mapM_ (testDownMigration st) $ drop (length noDownMigrations) serverMigrations
+  closeDBStore st
+  removeFile testSchemaPath
+  where
+    testDownMigration st m = do
+      putStrLn $ "down migration " <> name m
+      let downMigr = fromJust $ toDownMigration m
+      schema <- getSchema testSchemaPath
+      Migrations.run st $ MTRUp [m]
+      schema' <- getSchema testSchemaPath
+      schema' `shouldNotBe` schema
+      Migrations.run st $ MTRDown [downMigr]
+      unless (name m `elem` skipComparisonForDownMigrations) $ do
+        schema'' <- getSchema testSchemaPath
+        schema'' `shouldBe` schema
+      Migrations.run st $ MTRUp [m]
+      schema''' <- getSchema testSchemaPath
+      schema''' `shouldBe` schema'
+
+skipComparisonForDownMigrations :: [String]
+skipComparisonForDownMigrations =
+  [ -- snd_secure moves to the bottom on down migration
+    "20250320_short_links"
+  ]
+
+getSchema :: FilePath -> IO String
+getSchema schemaPath = do
+  ci <- (Just "true" ==) <$> lookupEnv "CI"
+  let cmd =
+        ("pg_dump " <> B.unpack testServerDBConnstr <> " --schema " <> B.unpack testDBSchema)
+          <> " --schema-only --no-owner --no-privileges --no-acl --no-subscriptions --no-tablespaces > "
+          <> schemaPath
+  (code, out, err) <- readCreateProcessWithExitCode (shell cmd) ""
+  print code
+  putStrLn $ "out: " <> out
+  putStrLn $ "err: " <> err
+  threadDelay 20000
+  let sed = (if ci then "sed -i" else "sed -i ''")
+  void $ readCreateProcess (shell $ sed <> " '/^--/d' " <> schemaPath) ""
+  sch <- readFile schemaPath
+  sch `deepseq` pure sch
diff --git a/tests/Test.hs b/tests/Test.hs
index 14007eed8b..674c1aa182 100644
--- a/tests/Test.hs
+++ b/tests/Test.hs
@@ -2,7 +2,7 @@
 {-# LANGUAGE NamedFieldPuns #-}
 {-# LANGUAGE TypeApplications #-}
 
-import AgentTests (agentTests)
+import AgentTests (agentCoreTests, agentTests)
 import CLITests
 import Control.Concurrent (threadDelay)
 import qualified Control.Exception as E
@@ -44,6 +44,7 @@ import AgentTests.SchemaDump (schemaDumpTest)
 
 #if defined(dbServerPostgres)
 import SMPClient (testServerDBConnectInfo)
+import ServerTests.SchemaDump
 #endif
 
 #if defined(dbPostgres) || defined(dbServerPostgres)
@@ -83,10 +84,12 @@ main = do
           describe "Store log tests" storeLogTests
           describe "TRcvQueues tests" tRcvQueuesTests
           describe "Util tests" utilTests
+          describe "Agent core tests" agentCoreTests
 #if defined(dbServerPostgres)
-        aroundAll_ (postgressBracket testServerDBConnectInfo)
-          $ describe "SMP server via TLS, postgres+jornal message store" $ do
-              describe "SMP syntax" $ serverSyntaxTests (transport @TLS)
+        around_ (postgressBracket testServerDBConnectInfo) $
+          describe "Server schema dump" serverSchemaDumpTest
+        aroundAll_ (postgressBracket testServerDBConnectInfo) $
+          describe "SMP server via TLS, postgres+jornal message store" $
               before (pure (transport @TLS, ASType SQSPostgres SMSJournal)) serverTests
 #endif
         describe "SMP server via TLS, jornal message store" $ do