react-native-libsignal-client

A React Native wrapper around the official libsignal client library (Rust core exposed via Swift/Java/Kotlin bindings) enabling end‑to‑end encryption (Signal Protocol) in React Native apps.

Features

• Signal protocol primitives (identity keys, sessions, prekeys, message encryption/decryption)
• zkgroup / group-related APIs surfaced from upstream
• TypeScript typings
• Expo config plugin (adds iOS pod + required build settings automatically)
• Example app with runnable protocol tests

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Installation

npm install react-native-libsignal-client
# or
yarn add react-native-libsignal-client

Expo (Recommended)

Add the plugin to app.json / app.config.(js|ts):

{
  "expo": {
    "plugins": ["react-native-libsignal-client"]
  }
}

Then generate native projects and run:

npx expo prebuild
npx expo run:ios   # or: npx expo run:android

The plugin:

• Injects the LibSignalClient CocoaPod (tag pinned)
• Sets use_frameworks! :linkage => :dynamic (via expo-build-properties)
• Adds the required Rust FFI checksum environment line

React Native CLI (Bare) – iOS

1. Install Rust & targets (first time only):

   curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
   rustup target add aarch64-apple-ios x86_64-apple-ios aarch64-apple-ios-sim

2. Edit your ios/Podfile (if you are NOT using the Expo config plugin):

   platform :ios, '12.0'
   use_frameworks! :linkage => :dynamic
   
   ENV['LIBSIGNAL_FFI_PREBUILD_CHECKSUM'] ||= 'e12f6f64eb0ed503c363f3b3830c4c62976cceec04122cd6deee66f5106c482d'
   
   target 'YourApp' do
     # ... other pods
     pod 'LibSignalClient', :git => 'https://github.com/signalapp/libsignal.git', :tag => 'v0.70.0'
   end

3. Install pods:

   cd ios && pod install

4. Open the workspace or run:

   npx react-native run-ios

React Native CLI – Android

No extra Gradle configuration is required. (The library ships pure JS + native upstream dependency only on iOS via CocoaPods.)
If you hit Java compilation toolchain issues, ensure:

• Gradle JVM / toolchain uses Java 17+
• Android Gradle Plugin version aligns with your RN version

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Example Project & Tests

An example/ app is included (Expo prebuild output) that doubles as an integration test harness.

Run it:

cd example
yarn install
npx expo prebuild   # (only if you cleaned native)
npx expo run:ios    # or: npx expo run:android

During app startup it executes protocol tests found in example/tests/ (crypto/session/zkgroup scenarios).
You can modify or add tests there to validate your own flows.

Headless test tips:

• Add lightweight wrappers in example/tests/*.ts
• Use a physical device for performance‑sensitive benchmarking

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Upgrading libsignal Version

The plugin currently pins:

tag: v0.70.0
checksum: e12f6f64eb0ed503c363f3b3830c4c62976cceec04122cd6deee66f5106c482d

To override (Expo users):

{
  "expo": {
    "plugins": [
      ["react-native-libsignal-client", { "tag": "v0.71.0", "checksum": "<new_checksum>" }]
    ]
  }
}

(Option support to be documented once exposed—until then, fork or patch the plugin.)

Bare users: change the :tag and checksum line in your Podfile and run pod update LibSignalClient.

Obtain the new checksum from the upstream libsignal GitHub Release notes.

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Usage (Basic Flow)

import {
  PrivateKey,
  ProtocolAddress,
  SessionBuilder,
  SessionCipher,
  PreKeyBundle,
} from 'react-native-libsignal-client';

// Identity + registration
const identityKey = PrivateKey.generate();
const registrationId = 42; // store persistently

// Suppose you received a remote prekey bundle (preKeyBundleJson)
const bundle: PreKeyBundle = PreKeyBundle.deserialize(preKeyBundleJson);

const address = new ProtocolAddress('alice', 1);
const store = /* implement & provide a SignalProtocolStore-like object */;

const builder = new SessionBuilder(store, address);
await builder.processPreKeyBundle(bundle);

// Encrypt
const cipher = new SessionCipher(store, address);
const { type, body } = await cipher.encrypt(Buffer.from('Hello, Signal!'));

// Decrypt
const plaintext = await cipher.decrypt(type, body);
console.log(plaintext.toString());

Persistence: You must implement storage interfaces (identity, sessions, prekeys, signed prekeys, one-time prekeys). Keep them consistent across launches; losing them will break decryption.

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iOS Framework / Static Pod Workarounds

Because use_frameworks! :linkage => :dynamic is required for the Swift-based LibSignalClient pod, some React Native pods (notably RNReanimated, sometimes RNScreens) can fail to link with errors like:

Undefined symbols for architecture arm64
_OBJC_CLASS_$_RCTEventDispatcher

This is a known CocoaPods + mixed linkage quirk. The plugin automatically forces a minimal set of pods to build as static libraries to avoid these issues.

Default static overrides:

• RNReanimated
• RNScreens

You can customize:

{
  "expo": {
    "plugins": [
      [
        "react-native-libsignal-client",
        {
          "ios": {
            "staticPods": ["RNCMaskedView", "ExpoDocumentPicker"],   // add more
            "disableStaticWorkarounds": false
          }
        }
      ]
    ]
  }
}

Set disableStaticWorkarounds: true to remove the pre_install block and manage linkage manually.

Overriding libsignal Version / Checksum

The plugin pins a known-good upstream tag & checksum. To test a new upstream release:

{
  "expo": {
    "plugins": [
      [
        "react-native-libsignal-client",
        {
          "ios": {
            "libsignalTag": "v0.71.0",
            "libsignalChecksum": "<release_checksum>"
          }
        }
      ]
    ]
  }
}

(Checksum comes from the upstream release notes. A mismatch will cause the pod build script to fail early.)

How It Works (iOS)

1. use_frameworks! :linkage => :dynamic enables building Swift/C modules as frameworks.
2. LibSignalClient pod build script downloads / builds the Rust FFI for required architectures.
3. Static override block redefines build_type for selected pods so they link into the app binary, preventing missing React symbol linkage.
4. If you remove use_frameworks!, the pod will fail (Swift + Rust wrapper expects frameworks).

When to Add More Static Pods

Add a pod name to staticPods if:

• You see "Undefined symbols ..." referencing React classes from that pod.
• You get duplicate symbol errors after adding another dynamic framework—forcing one side static can help.

If everything builds, do not add more; keep surface minimal.

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License

This project is licensed under the GNU Affero General Public License v3.0 – see the LICENSE file.

It incorporates and depends on upstream libsignal (AGPL-3.0).

Using this library in your application subjects the combined work to AGPLv3 obligations (including network use). If you require a different licensing model, consult Signal’s upstream licensing/commercial options.

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Source Availability Notice

In compliance with AGPLv3, the complete corresponding source for this package is available at: https://github.com/your-org-or-user/react-native-libsignal-client

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Disclaimer

This binding is not an official Signal distribution. Review upstream changes and audit cryptographic handling for production deployments.

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Contributing

Issues and PRs are welcome. Please:

1. Keep changes minimal & auditable
2. Avoid reformat-only PRs
3. Do not bundle unrelated dependency bumps with feature changes

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Publishing

For maintainers: see PUBLISHING.md for details on the release process.

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Roadmap (Planned)

• Optional plugin params for tag / checksum
• Documentation for implementing stores

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