feat: Phase 3 — E2EE calls, Jitsi conferencing, help tab, web security model
- LiveKit call E2EE: CallE2EEManager exchanges encryption keys via Matrix to-device events (m.rtc.encryption_keys) for interop with Element X - Olm bootstrapped in index.html before Flutter init; main.dart logs result - Encrypted messages shown with lock icon and informative fallback text - Profile screen: key restore dialog + security setup (cross-signing/backup) - Jitsi feature: welcome screen (public, no login), conference tab, full-screen embed via JitsiMeetExternalAPI, JitsiLink parser for all common link formats - Help tab: expandable cards for encryption, video calls, account management - Web security model: no session persistence — device ID only across visits - Media auth: MSC3916 authenticated endpoint for avatars (Synapse 1.120+) - Router: welcome route as public landing page; jitsi route as public - Manifest/index.html: M8Chat branding, dark theme colours Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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lib/features/calls/data/call_e2ee.dart
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185
lib/features/calls/data/call_e2ee.dart
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// Version: 1.0.0 | Created: 2026-04-10
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// E2EE key exchange for LiveKit calls via Matrix to-device events.
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// Implements the m.rtc.encryption_keys protocol for interop with Element X.
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import 'dart:async';
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import 'dart:convert';
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import 'dart:math';
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import 'package:flutter/foundation.dart';
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import 'package:livekit_client/livekit_client.dart';
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import 'package:matrix/matrix.dart' show Client, DeviceKeys, ToDeviceEvent;
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/// Event type used by Element X / Element Call for key exchange.
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const kEncryptionKeysEventType = 'm.rtc.encryption_keys';
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/// Manages E2EE key generation, distribution, and reception for LiveKit calls.
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///
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/// Flow:
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/// 1. [init] creates a per-participant [BaseKeyProvider] and generates a local key.
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/// 2. After LiveKit connects, call [setLocalKey] with the local participant identity.
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/// 3. Call [sendKeyToParticipants] to share our key via encrypted to-device events.
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/// 4. Incoming keys from Element X are received via [Client.onToDeviceEvent] and
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/// set on the [BaseKeyProvider] automatically.
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class CallE2EEManager {
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CallE2EEManager({
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required Client client,
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required String matrixRoomId,
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}) : _client = client,
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_matrixRoomId = matrixRoomId;
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final Client _client;
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final String _matrixRoomId;
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BaseKeyProvider? _keyProvider;
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StreamSubscription<ToDeviceEvent>? _toDeviceSub;
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Uint8List? _localKey;
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final int _localKeyIndex = 0;
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BaseKeyProvider? get keyProvider => _keyProvider;
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/// Create the key provider and start listening for incoming keys.
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Future<BaseKeyProvider> init() async {
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_keyProvider = await BaseKeyProvider.create(sharedKey: false);
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// Generate a random 32-byte encryption key for our media tracks.
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_localKey = _secureRandomBytes(32);
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// Listen for incoming encryption keys from other call participants.
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_toDeviceSub = _client.onToDeviceEvent.stream.listen(_onToDeviceEvent);
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debugPrint('[E2EE] Key provider created, local key generated '
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'(${base64Encode(_localKey!).substring(0, 8)}…)');
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return _keyProvider!;
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}
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/// Set our local key on the provider using the LiveKit participant identity.
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/// Call this AFTER the LiveKit Room is connected and localParticipant is available.
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Future<void> setLocalKey(String localIdentity) async {
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if (_keyProvider == null || _localKey == null) return;
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await _keyProvider!.setRawKey(
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_localKey!,
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participantId: localIdentity,
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keyIndex: _localKeyIndex,
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);
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debugPrint('[E2EE] Local key set for identity=$localIdentity');
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}
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/// Send our encryption key to all other call members via encrypted to-device.
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Future<void> sendKeyToParticipants() async {
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if (_localKey == null) return;
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final room = _client.getRoomById(_matrixRoomId);
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if (room == null) {
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debugPrint('[E2EE] Room $_matrixRoomId not found — cannot send keys');
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return;
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}
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// Find other participants from the MSC3401 call.member state events.
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final memberEvents =
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room.states['org.matrix.msc3401.call.member'] ?? {};
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final content = <String, Object>{
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'keys': [
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{'index': _localKeyIndex, 'key': base64Encode(_localKey!)},
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],
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'call_id': '',
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'device_id': _client.deviceID ?? '',
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'room_id': _matrixRoomId,
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};
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for (final entry in memberEvents.entries) {
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final userId = entry.key;
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if (userId == _client.userID) continue;
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// Parse device_id from the call.member event to target the correct device.
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final memberships =
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entry.value.content['memberships'] as List<dynamic>? ?? [];
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if (memberships.isEmpty) continue;
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await _client.userDeviceKeysLoading;
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final deviceKeyMap = _client.userDeviceKeys[userId]?.deviceKeys;
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if (deviceKeyMap == null || deviceKeyMap.isEmpty) {
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debugPrint('[E2EE] No device keys for $userId — skipping');
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continue;
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}
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// Send to all devices of this user that are in the call.
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final List<DeviceKeys> targets = [];
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for (final m in memberships) {
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final deviceId = m['device_id'] as String?;
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if (deviceId != null && deviceKeyMap.containsKey(deviceId)) {
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targets.add(deviceKeyMap[deviceId]!);
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}
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}
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// Fallback: if no specific device matched, send to all devices.
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if (targets.isEmpty) {
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targets.addAll(deviceKeyMap.values);
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}
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try {
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await _client.sendToDeviceEncrypted(
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targets,
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kEncryptionKeysEventType,
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content,
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);
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debugPrint(
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'[E2EE] Sent key to $userId (${targets.length} device(s))');
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} catch (e) {
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debugPrint('[E2EE] Failed to send key to $userId: $e');
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}
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}
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}
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/// Handle incoming to-device encryption key events from other participants.
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void _onToDeviceEvent(ToDeviceEvent event) {
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if (event.type != kEncryptionKeysEventType) return;
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// Only process keys for our active call room.
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final eventRoomId = event.content['room_id'] as String?;
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if (eventRoomId != null && eventRoomId != _matrixRoomId) return;
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final keys = event.content['keys'] as List<dynamic>?;
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if (keys == null || keys.isEmpty) {
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debugPrint(
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'[E2EE] Received $kEncryptionKeysEventType with empty keys '
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'from ${event.sender}');
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return;
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}
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final senderId = event.sender;
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debugPrint('[E2EE] Received encryption key(s) from $senderId');
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for (final keyEntry in keys) {
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final index = (keyEntry['index'] as num?)?.toInt() ?? 0;
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final keyB64 = keyEntry['key'] as String?;
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if (keyB64 == null) continue;
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final keyBytes = base64Decode(keyB64);
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// The participant identity in LiveKit should match the Matrix user ID
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// (set by lk-jwt-service). Log both for debugging.
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_keyProvider?.setRawKey(
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keyBytes,
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participantId: senderId,
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keyIndex: index,
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);
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debugPrint(
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'[E2EE] Key set for participant=$senderId index=$index '
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'(${keyB64.substring(0, 8)}…)');
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}
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}
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Future<void> dispose() async {
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await _toDeviceSub?.cancel();
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_toDeviceSub = null;
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_localKey = null;
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_keyProvider = null;
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debugPrint('[E2EE] Disposed');
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}
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static Uint8List _secureRandomBytes(int length) {
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final rng = Random.secure();
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return Uint8List.fromList(
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List<int>.generate(length, (_) => rng.nextInt(256)));
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}
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}
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