feat(appstore): sign the catalogue and verify it fail-closed

Replace the placeholder catalogue trust anchor with a real embedded
ed25519 key (internal/catalogtrust, ldflags-overridable for rotation):

- pilotctl loadCatalogue fetches a detached <url>.sig and verifies it
  against the embedded key before trusting any entry; unsigned, missing,
  or tampered catalogues are refused.
- New 'pilotctl appstore sign-catalogue' writes the detached signature and
  refuses to sign with a key that doesn't match the embedded public key.
- cmd/daemon passes the embedded key into appstore.Config.CatalogPubkey,
  retiring the all-zeros placeholder at the wire-up point.
- Sign catalogue.json; document signing + key rotation in catalogue README.

Tests: catalogtrust verify (happy/tamper/short/no-key), signed-catalogue
load + fail-closed (missing sig, tamper).

Author: teovl

catalogue/README.md

@@ -59,16 +59,49 @@ from a remote — operators relying on a catalogue do so over `https` only).
    equivalent — GitHub releases, Cloudflare R2, anywhere reachable over
    HTTPS).
 5. Update this `catalogue.json` with the new `version`, `bundle_url`, and
-   `bundle_sha256`. Commit. The change goes live the moment the commit
-   lands on `main` and the raw URL serves the new bytes — no daemon
-   restart, no pilotctl release.
+   `bundle_sha256`.
+6. **Re-sign the catalogue** (the signature covers the exact bytes, so it
+   must be regenerated on every edit):
+   ```bash
+   pilotctl appstore sign-catalogue --key /secure/path/catalog-signing.key \
+     catalogue/catalogue.json
+   ```
+   This writes `catalogue.json.sig` (detached, base64 ed25519). Commit
+   **both** `catalogue.json` and `catalogue.json.sig` together. The change
+   goes live the moment they land on `main` and the raw URLs serve the new
+   bytes — no daemon restart, no pilotctl release.
+
+`pilotctl` fetches `catalogue.json` **and** `catalogue.json.sig` and
+verifies the signature against the embedded catalogue public key before
+trusting any entry. An unsigned, missing-signature, or tampered catalogue
+is refused (fail-closed).
+
+## Catalogue signing key
+
+The catalogue is signed with a dedicated ed25519 key, separate from any
+app-publisher key. The **private** key is held by the release pipeline and
+is never committed. The **public** key is compiled into pilotctl and the
+daemon at `internal/catalogtrust` (`publicKeyB64`) and can be rotated at
+build time without a code change:
+
+```bash
+go build -ldflags \
+  "-X github.com/TeoSlayer/pilotprotocol/internal/catalogtrust.publicKeyB64=<new-b64-pubkey>" \
+  ./cmd/pilotctl ./cmd/daemon
+```
+
+To rotate: generate a new keypair, store the private key securely, update
+the embedded public key (source default or `-ldflags`), and re-sign the
+catalogue. `sign-catalogue` refuses to sign with a key that doesn't match
+the embedded public key, so a mismatch is caught before publishing a dead
+signature.
 
 ## Trust model
 
 | Layer | Trust anchor | Verifies |
 |---|---|---|
 | User trusts pilotctl | Project release pipeline (signed pilotctl binary) | The catalogue URL is correct |
-| pilotctl trusts the catalogue | Future: signed against `EmbeddedCatalogPubkey`; today: the raw URL itself | App IDs map to specific bundle URLs + SHAs |
+| pilotctl trusts the catalogue | Detached ed25519 signature against the embedded catalogue key (`internal/catalogtrust`) | The app list (IDs → bundle URLs + SHAs) is authentic; a substituted catalogue is rejected |
 | pilotctl trusts the bundle | Embedded `bundle_sha256` matches downloaded bytes | A CDN substitute is rejected |
 | Daemon trusts the manifest | Embedded ed25519 publisher pubkey verifies the signature | The bundle's manifest hasn't been tampered with |
 

catalogue/catalogue.json.sig

@@ -0,0 +1 @@
+CD3TrFKmG4MxgX0eK85z6jPgqpH3gb6+8px87iVALCYF7x7//FqByN3CCkBtHIgxgDUE5afGKJptWNpddw6SCw==

cmd/daemon/main.go

@@ -33,6 +33,8 @@ import (
 	"github.com/pilot-protocol/skillinject"
 	"github.com/pilot-protocol/trustedagents"
 	"github.com/pilot-protocol/webhook"
+
+	"github.com/TeoSlayer/pilotprotocol/internal/catalogtrust"
 )
 
 var version = "dev"
@@ -279,6 +281,9 @@ func main() {
 	if err := rt.Register(&appstoreAdapter{svc: appstore.NewService(appstore.Config{
 		InstallRoot:    appstoreInstallRoot,
 		RescanInterval: 2 * time.Second,
+		// Real catalogue trust anchor (replaces the all-zeros
+		// placeholder default): the embedded ed25519 catalogue key.
+		CatalogPubkey: []byte(catalogtrust.PublicKey()),
 	})}); err != nil {
 		log.Fatalf("register appstore: %v", err)
 	}

cmd/pilotctl/appstore.go

@@ -67,6 +67,8 @@ func cmdAppStore(args []string) {
 		cmdAppStoreGenKey(args[1:])
 	case "sign":
 		cmdAppStoreSign(args[1:])
+	case "sign-catalogue", "sign-catalog":
+		cmdAppStoreSignCatalogue(args[1:])
 	case "catalogue", "catalog":
 		cmdAppStoreCatalogue(args[1:])
 	case "restart":
@@ -79,7 +81,7 @@ func cmdAppStore(args []string) {
 		appStoreHelp()
 	default:
 		fatalHint("invalid_argument",
-			"available: list, status, audit, uninstall, verify, install, gen-key, sign, catalogue, restart, caps, actions, call",
+			"available: list, status, audit, uninstall, verify, install, gen-key, sign, sign-catalogue, catalogue, restart, caps, actions, call",
 			"unknown appstore subcommand: %s", args[0])
 	}
 }
@@ -110,6 +112,8 @@ Usage:
   pilotctl appstore gen-key <key-file>       generate a fresh ed25519 publisher keypair; prints the public side
   pilotctl appstore sign --key <key-file> <manifest>
                                              sign (or re-sign) a manifest's store.signature so the supervisor accepts it
+  pilotctl appstore sign-catalogue --key <key-file> <catalogue.json>
+                                             sign the catalogue, writing a detached <catalogue>.sig pilotctl verifies on load
   pilotctl appstore restart <id>             ask the daemon to clear crash-loop suspension and respawn this app
   pilotctl appstore caps <id>                show the manifest's spend caps and current rolling-window usage
   pilotctl appstore actions [--tail N] [--event NAME]

cmd/pilotctl/appstore_catalogue.go

@@ -33,8 +33,11 @@ package main
 
 import (
 	"archive/tar"
+	"bytes"
 	"compress/gzip"
+	"crypto/ed25519"
 	"crypto/sha256"
+	"encoding/base64"
 	"encoding/hex"
 	"encoding/json"
 	"errors"
@@ -46,6 +49,8 @@ import (
 	"path/filepath"
 	"strings"
 	"time"
+
+	"github.com/TeoSlayer/pilotprotocol/internal/catalogtrust"
 )
 
 // defaultCatalogueURL points at the canonical catalogue.json on main.
@@ -90,14 +95,25 @@ func catalogueURL() string {
 // garbage.
 func loadCatalogue() (*catalogue, error) {
 	u := catalogueURL()
-	body, err := openURL(u)
+	data, err := fetchAll(u)
 	if err != nil {
 		return nil, fmt.Errorf("fetch catalogue from %s: %w", u, err)
 	}
-	defer body.Close()
-	data, err := io.ReadAll(io.LimitReader(body, 1<<20)) // 1 MiB cap
+	// Fail-closed signature gate: the catalogue must carry a detached
+	// ed25519 signature (at <url>.sig) that verifies against the embedded
+	// catalogue public key. A compromised CDN/host can't substitute a
+	// different app list (pointing installs at hostile bundle URLs)
+	// without also forging this signature.
+	sigRaw, err := fetchAll(u + ".sig")
+	if err != nil {
+		return nil, fmt.Errorf("fetch catalogue signature %s.sig: %w (the catalogue must be signed; see catalogue/README.md)", u, err)
+	}
+	sig, err := base64.StdEncoding.DecodeString(strings.TrimSpace(string(sigRaw)))
 	if err != nil {
-		return nil, fmt.Errorf("read catalogue body: %w", err)
+		return nil, fmt.Errorf("decode catalogue signature: %w", err)
+	}
+	if err := catalogtrust.Verify(data, sig); err != nil {
+		return nil, fmt.Errorf("catalogue signature: %w", err)
 	}
 	var c catalogue
 	if err := json.Unmarshal(data, &c); err != nil {
@@ -109,6 +125,87 @@ func loadCatalogue() (*catalogue, error) {
 	return &c, nil
 }
 
+// fetchAll opens raw via openURL and reads the whole body (1 MiB cap).
+func fetchAll(raw string) ([]byte, error) {
+	body, err := openURL(raw)
+	if err != nil {
+		return nil, err
+	}
+	defer body.Close()
+	data, err := io.ReadAll(io.LimitReader(body, 1<<20)) // 1 MiB cap
+	if err != nil {
+		return nil, fmt.Errorf("read body: %w", err)
+	}
+	return data, nil
+}
+
+// cmdAppStoreSignCatalogue signs a catalogue.json with the catalogue
+// signing key, writing a detached base64 ed25519 signature to
+// <catalogue>.sig. The signing key must match the embedded catalogue
+// public key (catalogtrust.PublicKey) — otherwise pilotctl would reject
+// the signature at load, so we refuse to produce a dead signature.
+//
+//	pilotctl appstore sign-catalogue --key <key-file> <catalogue.json>
+func cmdAppStoreSignCatalogue(args []string) {
+	var keyFile string
+	rest := args
+	for len(rest) > 0 && (rest[0] == "--key" || rest[0] == "-k") {
+		if len(rest) < 2 {
+			fatalHint("invalid_argument", "--key takes a path", "missing value after %s", rest[0])
+		}
+		keyFile = rest[1]
+		rest = rest[2:]
+	}
+	if keyFile == "" || len(rest) == 0 {
+		fatalHint("invalid_argument",
+			"usage: pilotctl appstore sign-catalogue --key <key-file> <catalogue.json>",
+			"missing --key or catalogue path")
+	}
+	cataloguePath := rest[0]
+
+	keyHex, err := os.ReadFile(keyFile)
+	if err != nil {
+		fatalHint("io_error", "the key path doesn't exist or is unreadable", "read key: %v", err)
+	}
+	privBytes, err := hex.DecodeString(strings.TrimSpace(string(keyHex)))
+	if err != nil {
+		fatalHint("invalid_argument", "the file should be a single hex-encoded ed25519 private key", "decode key: %v", err)
+	}
+	if len(privBytes) != ed25519.PrivateKeySize {
+		fatalHint("invalid_argument", fmt.Sprintf("expected %d bytes; got %d", ed25519.PrivateKeySize, len(privBytes)), "key length mismatch")
+	}
+	priv := ed25519.PrivateKey(privBytes)
+	pub := priv.Public().(ed25519.PublicKey)
+
+	// Guard: refuse to sign with a key that doesn't match the embedded
+	// trust anchor — the resulting .sig would never verify in the wild.
+	embed := catalogtrust.PublicKey()
+	if embed == nil {
+		fatalHint("internal_error", "rebuild pilotctl with a valid embedded catalogue key", "embedded catalogue public key is missing/malformed")
+	}
+	if !bytes.Equal(pub, embed) {
+		fatalHint("invalid_argument",
+			"this key does not match the embedded catalogue public key; pilotctl would reject the signature. Use the release catalogue key, or rebuild pilotctl with -ldflags overriding catalogtrust.publicKeyB64",
+			"signing key pubkey %s != embedded %s",
+			base64.StdEncoding.EncodeToString(pub), base64.StdEncoding.EncodeToString(embed))
+	}
+
+	data, err := os.ReadFile(cataloguePath)
+	if err != nil {
+		fatalHint("io_error", "pass the path to a catalogue.json file", "read catalogue: %v", err)
+	}
+	sig := ed25519.Sign(priv, data)
+	if err := catalogtrust.Verify(data, sig); err != nil {
+		fatalHint("internal_error", "self-verify after signing failed — bug", "%v", err)
+	}
+	sigPath := cataloguePath + ".sig"
+	if err := os.WriteFile(sigPath, []byte(base64.StdEncoding.EncodeToString(sig)+"\n"), 0o644); err != nil {
+		fatalHint("io_error", "check the catalogue dir is writable", "write signature: %v", err)
+	}
+	fmt.Printf("signed %s\n", cataloguePath)
+	fmt.Printf("signature: %s\n", sigPath)
+}
+
 func cmdAppStoreCatalogue(_ []string) {
 	c, err := loadCatalogue()
 	if err != nil {

cmd/pilotctl/zz_appstore_signed_catalogue_test.go

@@ -0,0 +1,84 @@
+package main
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+// repoCataloguePath returns the path to the repo's signed catalogue,
+// skipping if it (or its detached signature) isn't present.
+func repoCataloguePath(t *testing.T) string {
+	t.Helper()
+	wd, err := os.Getwd() // .../web4/cmd/pilotctl
+	if err != nil {
+		t.Fatal(err)
+	}
+	p := filepath.Join(wd, "..", "..", "catalogue", "catalogue.json")
+	if _, err := os.Stat(p); err != nil {
+		t.Skipf("repo catalogue not found at %s: %v", p, err)
+	}
+	if _, err := os.Stat(p + ".sig"); err != nil {
+		t.Skipf("repo catalogue signature not found: %v", err)
+	}
+	return p
+}
+
+// TestLoadCatalogue_VerifiesSignedRepoCatalogue confirms the committed
+// catalogue verifies against the embedded catalogue key (the .sig in the
+// repo must be signed by the embedded key — this guards that invariant).
+func TestLoadCatalogue_VerifiesSignedRepoCatalogue(t *testing.T) {
+	p := repoCataloguePath(t)
+	t.Setenv("PILOT_APPSTORE_CATALOG_URL", "file://"+p)
+	c, err := loadCatalogue()
+	if err != nil {
+		t.Fatalf("loadCatalogue on signed repo catalogue: %v", err)
+	}
+	if len(c.Apps) == 0 {
+		t.Error("expected at least one app in the signed catalogue")
+	}
+}
+
+// TestLoadCatalogue_FailsClosedWithoutSignature asserts a catalogue with
+// no detached signature is rejected.
+func TestLoadCatalogue_FailsClosedWithoutSignature(t *testing.T) {
+	dir := t.TempDir()
+	data, err := os.ReadFile(repoCataloguePath(t))
+	if err != nil {
+		t.Fatal(err)
+	}
+	dst := filepath.Join(dir, "catalogue.json")
+	if err := os.WriteFile(dst, data, 0o644); err != nil {
+		t.Fatal(err)
+	}
+	t.Setenv("PILOT_APPSTORE_CATALOG_URL", "file://"+dst)
+	if _, err := loadCatalogue(); err == nil {
+		t.Error("loadCatalogue must fail closed when the signature is missing")
+	}
+}
+
+// TestLoadCatalogue_FailsOnTamper asserts a modified catalogue fails the
+// signature check even when a (now-stale) signature is present.
+func TestLoadCatalogue_FailsOnTamper(t *testing.T) {
+	dir := t.TempDir()
+	src := repoCataloguePath(t)
+	data, err := os.ReadFile(src)
+	if err != nil {
+		t.Fatal(err)
+	}
+	sig, err := os.ReadFile(src + ".sig")
+	if err != nil {
+		t.Fatal(err)
+	}
+	dst := filepath.Join(dir, "catalogue.json")
+	if err := os.WriteFile(dst, append(data, ' '), 0o644); err != nil { // tamper
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(dst+".sig", sig, 0o644); err != nil {
+		t.Fatal(err)
+	}
+	t.Setenv("PILOT_APPSTORE_CATALOG_URL", "file://"+dst)
+	if _, err := loadCatalogue(); err == nil {
+		t.Error("loadCatalogue must reject a tampered catalogue")
+	}
+}

internal/catalogtrust/catalogtrust.go

@@ -0,0 +1,60 @@
+// Package catalogtrust holds the app-store catalogue trust anchor: the
+// ed25519 public key the signed catalogue is verified against, plus a
+// verify helper. The matching private key is held by the release
+// pipeline and is never committed (see catalogue/README.md).
+//
+// This replaces the all-zeros placeholder trust anchor: pilotctl verifies
+// the catalogue signature against PublicKey() before trusting any
+// install target, and the daemon passes PublicKey() into the app-store
+// service so its Start-time trust-anchor check sees a real key.
+package catalogtrust
+
+import (
+	"crypto/ed25519"
+	"encoding/base64"
+	"errors"
+	"fmt"
+)
+
+// publicKeyB64 is the base64-encoded ed25519 catalogue-signing public
+// key. Overridable at build time to rotate the key without a code change:
+//
+//	-ldflags "-X github.com/TeoSlayer/pilotprotocol/internal/catalogtrust.publicKeyB64=<b64>"
+//
+// The compiled-in default is the current production catalogue key.
+var publicKeyB64 = "5aCD92R0UoZ2lGW6PYZeRrDw63ZNBC5oJZxFB8RNOPQ="
+
+// ErrNoKey is returned when the embedded key is missing or malformed.
+// Fail-closed: with no trust anchor, nothing verifies.
+var ErrNoKey = errors.New("catalogtrust: no valid embedded catalogue public key")
+
+// ErrBadSignature is returned when a signature does not verify against
+// the embedded key.
+var ErrBadSignature = errors.New("catalogtrust: catalogue signature verification failed")
+
+// PublicKey returns the embedded catalogue public key, or nil if the
+// embedded value is malformed (e.g. a bad ldflags override).
+func PublicKey() ed25519.PublicKey {
+	raw, err := base64.StdEncoding.DecodeString(publicKeyB64)
+	if err != nil || len(raw) != ed25519.PublicKeySize {
+		return nil
+	}
+	return ed25519.PublicKey(raw)
+}
+
+// Verify checks that sig is a valid ed25519 signature over data, made
+// with the catalogue signing key. Fail-closed on a missing/invalid
+// embedded key or a wrong-length signature.
+func Verify(data, sig []byte) error {
+	pk := PublicKey()
+	if pk == nil {
+		return ErrNoKey
+	}
+	if len(sig) != ed25519.SignatureSize {
+		return fmt.Errorf("%w: wrong signature length %d (want %d)", ErrBadSignature, len(sig), ed25519.SignatureSize)
+	}
+	if !ed25519.Verify(pk, data, sig) {
+		return ErrBadSignature
+	}
+	return nil
+}