CHANGELOG.md

@@ -50,7 +50,3 @@
 ## 0.4.2
 
 - Fix removeAllRatchets not removing, well, all ratchets. In fact, it did not remove any ratchet.
-
-## 0.4.3
-
-- Fix bug that causes ratchets to be unable to decrypt anything after receiving a heartbeat with a completely new session

README.md

@@ -28,7 +28,7 @@ Include `omemo_dart` in your `pubspec.yaml` like this:
 dependencies:
   omemo_dart:
     hosted: https://git.polynom.me/api/packages/PapaTutuWawa/pub
-    version: ^0.4.3
+    version: ^0.4.0
   # [...]
 
 # [...]

lib/src/omemo/events.dart

@@ -5,16 +5,13 @@ abstract class OmemoEvent {}
 
 /// Triggered when a ratchet has been modified
 class RatchetModifiedEvent extends OmemoEvent {
-  RatchetModifiedEvent(this.jid, this.deviceId, this.ratchet, this.added, this.replaced);
+  RatchetModifiedEvent(this.jid, this.deviceId, this.ratchet, this.added);
   final String jid;
   final int deviceId;
   final OmemoDoubleRatchet ratchet;
 
   /// Indicates whether the ratchet has just been created (true) or just modified (false).
   final bool added;
-
-  /// Indicates whether the ratchet has been replaced (true) or not.
-  final bool replaced;
 }
 
 /// Triggered when a ratchet has been removed and should be removed from storage.

lib/src/omemo/omemomanager.dart

@@ -29,13 +29,8 @@ import 'package:omemo_dart/src/x3dh/x3dh.dart';
 import 'package:synchronized/synchronized.dart';
 
 class _InternalDecryptionResult {
-  const _InternalDecryptionResult(
+  const _InternalDecryptionResult(this.ratchetCreated, this.payload);
-    this.ratchetCreated,
-    this.ratchetReplaced,
-    this.payload,
-  ) : assert(!ratchetCreated || !ratchetReplaced, 'Ratchet must be either replaced or created');
   final bool ratchetCreated;
-  final bool ratchetReplaced;
   final String? payload;
 }
 
@@ -167,7 +162,7 @@ class OmemoManager {
     _ratchetMap[key] = ratchet;
 
     // Commit the ratchet
-    _eventStreamController.add(RatchetModifiedEvent(jid, deviceId, ratchet, true, false));
+    _eventStreamController.add(RatchetModifiedEvent(jid, deviceId, ratchet, true));
   }
 
   /// Build a new session with the user at [jid] with the device [deviceId] using data
@@ -248,7 +243,6 @@ class OmemoManager {
         mapKey.deviceId,
         oldRatchet,
         false,
-        false,
       ),
     );
   }
@@ -273,16 +267,17 @@ class OmemoManager {
       throw NotEncryptedForDeviceException();
     }
 
+    final ratchetKey = RatchetMapKey(senderJid, senderDeviceId);
     final decodedRawKey = base64.decode(rawKey.value);
     List<int>? keyAndHmac;
     OmemoAuthenticatedMessage authMessage;
+    OmemoDoubleRatchet? oldRatchet;
     OmemoMessage? message;
-
+    var ratchetCreated = false;
-    // If the ratchet already existed, we store it. If it didn't, oldRatchet will stay
-    // null.
-    final ratchetKey = RatchetMapKey(senderJid, senderDeviceId);
-    final oldRatchet = getRatchet(ratchetKey)?.clone();
     if (rawKey.kex) {
+      // If the ratchet already existed, we store it. If it didn't, oldRatchet will stay
+      // null.
+      final oldRatchet = getRatchet(ratchetKey)?.clone();
       final kex = OmemoKeyExchange.fromBuffer(decodedRawKey);
       authMessage = kex.message!;
       message = OmemoMessage.fromBuffer(authMessage.message!);
@@ -293,45 +288,48 @@ class OmemoManager {
         if (oldRatchet.kexTimestamp > timestamp) {
           throw InvalidKeyExchangeException();
         }
+        
+        // Try to decrypt it
+        try {
+          final decrypted = await oldRatchet.ratchetDecrypt(message, authMessage.writeToBuffer());
+
+          // Commit the ratchet
+          _eventStreamController.add(
+            RatchetModifiedEvent(
+              senderJid,
+              senderDeviceId,
+              oldRatchet,
+              false,
+            ),
+          );
+          
+          final plaintext = await _decryptAndVerifyHmac(
+            ciphertext,
+            decrypted,
+          );
+          _addSession(senderJid, senderDeviceId, oldRatchet);
+          return _InternalDecryptionResult(
+            true,
+            plaintext,
+          );
+        } catch (_) {
+          _log.finest('Failed to use old ratchet with KEX for existing ratchet');
+        }
       }
 
       final r = await _addSessionFromKeyExchange(senderJid, senderDeviceId, kex);
+      await _trustManager.onNewSession(senderJid, senderDeviceId);
+      _addSession(senderJid, senderDeviceId, r);
+      ratchetCreated = true;
 
-      // Try to decrypt with the new ratchet r
+      // Replace the OPK
-      try {
+      // TODO(PapaTutuWawa): Replace the OPK when we know that the KEX worked
-        keyAndHmac = await r.ratchetDecrypt(message, authMessage.writeToBuffer());
+      await _deviceLock.synchronized(() async {
-        final result = await _decryptAndVerifyHmac(ciphertext, keyAndHmac);
+        device = await device.replaceOnetimePrekey(kex.pkId!);
 
-        // Add the new ratchet
+        // Commit the device
-        _addSession(senderJid, senderDeviceId, r);
+        _eventStreamController.add(DeviceModifiedEvent(device));
-
+      });
-        // Replace the OPK
-        await _deviceLock.synchronized(() async {
-          device = await device.replaceOnetimePrekey(kex.pkId!);
-
-          // Commit the device
-          _eventStreamController.add(DeviceModifiedEvent(device));
-        });
-
-        // Commit the ratchet
-        _eventStreamController.add(
-          RatchetModifiedEvent(
-            senderJid,
-            senderDeviceId,
-            r,
-            oldRatchet == null,
-            oldRatchet != null,
-          ),
-        );
-
-        return _InternalDecryptionResult(
-          oldRatchet == null,
-          oldRatchet != null,
-          result,
-        );
-      } catch (ex) {
-        _log.finest('Kex failed due to $ex. Not proceeding with kex.');
-      }
     } else {
       authMessage = OmemoAuthenticatedMessage.fromBuffer(decodedRawKey);
       message = OmemoMessage.fromBuffer(authMessage.message!);
@@ -342,10 +340,9 @@ class OmemoManager {
       throw NoDecryptionKeyException();
     }
 
-    // TODO(PapaTutuWawa): When receiving a message that is not an OMEMOKeyExchange from a device there is no session with, clients SHOULD create a session with that device and notify it about the new session by responding with an empty OMEMO message as per Sending a message.
-    
     // We can guarantee that the ratchet exists at this point in time
     final ratchet = getRatchet(ratchetKey)!;
+    oldRatchet ??= ratchet.clone();
 
     try {
       if (rawKey.kex) {
@@ -354,7 +351,7 @@ class OmemoManager {
         keyAndHmac = await ratchet.ratchetDecrypt(message, decodedRawKey);
       }
     } catch (_) {
-      _restoreRatchet(ratchetKey, oldRatchet!);
+      _restoreRatchet(ratchetKey, oldRatchet);
       rethrow;
     }
 
@@ -365,18 +362,16 @@ class OmemoManager {
         senderDeviceId,
         ratchet,
         false,
-        false,
       ),
     );
 
     try {
       return _InternalDecryptionResult(
-        false,
+        ratchetCreated,
-        false,
         await _decryptAndVerifyHmac(ciphertext, keyAndHmac),
       );
     } catch (_) { 
-      _restoreRatchet(ratchetKey, oldRatchet!);
+      _restoreRatchet(ratchetKey, oldRatchet);
       rethrow;
     }
   }
@@ -556,7 +551,7 @@ class OmemoManager {
         }
 
         // Commit the ratchet
-        _eventStreamController.add(RatchetModifiedEvent(jid, deviceId, ratchet, false, false));
+        _eventStreamController.add(RatchetModifiedEvent(jid, deviceId, ratchet, false));
       }
     }
 
@@ -605,7 +600,7 @@ class OmemoManager {
 
     if (ratchet!.acknowledged) {
       // Ratchet is acknowledged
-      if (ratchet.nr > 53 || result.ratchetCreated || result.ratchetReplaced) {
+      if (ratchet.nr > 53 || result.ratchetCreated) {
         await sendEmptyOmemoMessageImpl(
           await _encryptToJids(
             [stanza.bareSenderJid],
@@ -682,7 +677,7 @@ class OmemoManager {
         ..acknowledged = true;
 
       // Commit it
-      _eventStreamController.add(RatchetModifiedEvent(jid, deviceId, ratchet, false, false));
+      _eventStreamController.add(RatchetModifiedEvent(jid, deviceId, ratchet, false));
     } else {
       _log.severe('Attempted to acknowledge ratchet ${key.toJsonKey()}, even though it does not exist');
     }

lib/src/omemo/sessionmanager.dart

@@ -136,7 +136,7 @@ class OmemoSessionManager {
       _ratchetMap[key] = ratchet;
 
       // Commit the ratchet
-      _eventStreamController.add(RatchetModifiedEvent(jid, deviceId, ratchet, true, false));
+      _eventStreamController.add(RatchetModifiedEvent(jid, deviceId, ratchet, true));
     });
   }
 
@@ -321,7 +321,7 @@ class OmemoSessionManager {
           }
 
           // Commit the ratchet
-          _eventStreamController.add(RatchetModifiedEvent(jid, deviceId, ratchet, false, false));
+          _eventStreamController.add(RatchetModifiedEvent(jid, deviceId, ratchet, false));
         }
       }
     });
@@ -349,7 +349,6 @@ class OmemoSessionManager {
           mapKey.deviceId,
           oldRatchet,
           false,
-          false,
         ),
       );
     });
@@ -426,7 +425,6 @@ class OmemoSessionManager {
               senderDeviceId,
               oldRatchet,
               false,
-              false,
             ),
           );
           
@@ -488,7 +486,6 @@ class OmemoSessionManager {
         senderDeviceId,
         ratchet,
         false,
-        false,
       ),
     );
 
@@ -620,7 +617,7 @@ class OmemoSessionManager {
         ..acknowledged = true;
 
       // Commit it
-      _eventStreamController.add(RatchetModifiedEvent(jid, deviceId, ratchet, false, false));
+      _eventStreamController.add(RatchetModifiedEvent(jid, deviceId, ratchet, false));
     });
   }
 

pubspec.yaml

@@ -1,6 +1,6 @@
 name: omemo_dart
 description: An XMPP library independent OMEMO library
-version: 0.4.3
+version: 0.4.2
 homepage: https://github.com/PapaTutuWawa/omemo_dart
 publish_to: https://git.polynom.me/api/packages/PapaTutuWawa/pub
 

test/omemomanager_test.dart

@@ -1,7 +1,6 @@
 import 'dart:convert';
 import 'package:logging/logging.dart';
 import 'package:omemo_dart/omemo_dart.dart';
-import 'package:omemo_dart/src/protobuf/omemo_key_exchange.dart';
 import 'package:omemo_dart/src/trust/always.dart';
 import 'package:test/test.dart';
 
@@ -951,13 +950,10 @@ void main() {
     final aliceDevice = await OmemoDevice.generateNewDevice(aliceJid, opkAmount: 1);
     final bobDevice = await OmemoDevice.generateNewDevice(bobJid, opkAmount: 1);
 
-    EncryptionResult? aliceEmptyMessage;
     final aliceManager = OmemoManager(
       aliceDevice,
       AlwaysTrustingTrustManager(),
-      (result, recipientJid) async {
+      (result, recipientJid) async {},
-        aliceEmptyMessage = result;
-      },
       (jid) async {
         expect(jid, bobJid);
 
@@ -1009,284 +1005,14 @@ void main() {
 
     expect(aliceManager.getRatchet(RatchetMapKey(bobJid, bobDevice.id)), null);
 
-    // Alice prepares an empty OMEMO message
-    await aliceManager.sendOmemoHeartbeat(bobJid);
-
-    // And Bob receives it
-    final bobResult2 = await bobManager.onIncomingStanza(
-      OmemoIncomingStanza(
-        aliceJid,
-        await aliceManager.getDeviceId(),
-        DateTime.now().millisecondsSinceEpoch,
-        aliceEmptyMessage!.encryptedKeys,
-        null,
-      ),
-    );
-    expect(bobResult2.error, null);
-
-    // Bob acks the new ratchet
-    await aliceManager.ratchetAcknowledged(
-      bobJid,
-      await bobManager.getDeviceId(),
-    );
-    
-    // Alice sends another message
-    final aliceResult3 = await aliceManager.onOutgoingStanza(
-      const OmemoOutgoingStanza(
-        [bobJid],
-        'I did not trust your last device, Bob!',
-      ),
-    );
-
-    // Bob decrypts it
-    final bobResult3 = await bobManager.onIncomingStanza(
-      OmemoIncomingStanza(
-        aliceJid,
-        aliceDevice.id,
-        DateTime.now().millisecondsSinceEpoch,
-        aliceResult3.encryptedKeys,
-        base64.encode(aliceResult3.ciphertext!),
-      ),
-    );
-
-    expect(bobResult3.error, null);
-    expect(bobResult3.payload, 'I did not trust your last device, Bob!');
-
-    // Bob responds
-    final bobResult4 = await bobManager.onOutgoingStanza(
-      const OmemoOutgoingStanza(
-        [aliceJid],
-        "That's okay.",
-      ),
-    );
-
-    // Alice decrypts
-    final aliceResult4 = await aliceManager.onIncomingStanza(
-      OmemoIncomingStanza(
-        bobJid,
-        bobDevice.id,
-        DateTime.now().millisecondsSinceEpoch,
-        bobResult4.encryptedKeys,
-        base64.encode(bobResult4.ciphertext!),
-      ),
-    );
-
-    expect(aliceResult4.error, null);
-    expect(aliceResult4.payload, "That's okay.");
-  });
-
-  test('Test removing all ratchets and sending a message without post-heartbeat ack', () async {
-    // This test is the same as "Test removing all ratchets and sending a message" except
-    // that bob does not ack the ratchet after Alice's heartbeat after she recreated
-    // all ratchets.
-    const aliceJid = 'alice@server1';
-    const bobJid = 'bob@server2';
-
-    final aliceDevice = await OmemoDevice.generateNewDevice(aliceJid, opkAmount: 1);
-    final bobDevice = await OmemoDevice.generateNewDevice(bobJid, opkAmount: 1);
-
-    EncryptionResult? aliceEmptyMessage;
-    final aliceManager = OmemoManager(
-      aliceDevice,
-      AlwaysTrustingTrustManager(),
-      (result, recipientJid) async {
-        aliceEmptyMessage = result;
-      },
-      (jid) async {
-        expect(jid, bobJid);
-
-        return [bobDevice.id];
-      },
-      (jid, id) async {
-        expect(jid, bobJid);
-
-        return bobDevice.toBundle();
-      },
-      (jid) async {},
-    );
-    final bobManager = OmemoManager(
-      bobDevice,
-      AlwaysTrustingTrustManager(),
-      (result, recipientJid) async {},
-      (jid) async => null,
-      (jid, id) async => null,
-      (jid) async {},
-    );
-
-    // Alice encrypts a message for Bob
-    final aliceResult1 = await aliceManager.onOutgoingStanza(
-      const OmemoOutgoingStanza(
-        [bobJid],
-        'Hello Bob!',
-      ),
-    );
-
-    // And Bob decrypts it
-    await bobManager.onIncomingStanza(
-      OmemoIncomingStanza(
-        aliceJid,
-        aliceDevice.id,
-        DateTime.now().millisecondsSinceEpoch,
-        aliceResult1.encryptedKeys,
-        base64.encode(aliceResult1.ciphertext!),
-      ),
-    );
-
-    // Ratchets are acked
-    await aliceManager.ratchetAcknowledged(
-      bobJid,
-      bobDevice.id,
-    );
-
-    // Alice now removes all ratchets for Bob and sends another new message
-    await aliceManager.removeAllRatchets(bobJid);
-
-    expect(aliceManager.getRatchet(RatchetMapKey(bobJid, bobDevice.id)), null);
-
-    // Alice prepares an empty OMEMO message
-    await aliceManager.sendOmemoHeartbeat(bobJid);
-
-    // And Bob receives it
-    final bobResult2 = await bobManager.onIncomingStanza(
-      OmemoIncomingStanza(
-        aliceJid,
-        await aliceManager.getDeviceId(),
-        DateTime.now().millisecondsSinceEpoch,
-        aliceEmptyMessage!.encryptedKeys,
-        null,
-      ),
-    );
-    expect(bobResult2.error, null);
-
-    // Alice sends another message
-    final aliceResult3 = await aliceManager.onOutgoingStanza(
-      const OmemoOutgoingStanza(
-        [bobJid],
-        'I did not trust your last device, Bob!',
-      ),
-    );
-
-    // Bob decrypts it
-    final bobResult3 = await bobManager.onIncomingStanza(
-      OmemoIncomingStanza(
-        aliceJid,
-        aliceDevice.id,
-        DateTime.now().millisecondsSinceEpoch,
-        aliceResult3.encryptedKeys,
-        base64.encode(aliceResult3.ciphertext!),
-      ),
-    );
-
-    expect(bobResult3.error, null);
-    expect(bobResult3.payload, 'I did not trust your last device, Bob!');
-
-    // Bob responds
-    final bobResult4 = await bobManager.onOutgoingStanza(
-      const OmemoOutgoingStanza(
-        [aliceJid],
-        "That's okay.",
-      ),
-    );
-
-    // Alice decrypts
-    final aliceResult4 = await aliceManager.onIncomingStanza(
-      OmemoIncomingStanza(
-        bobJid,
-        bobDevice.id,
-        DateTime.now().millisecondsSinceEpoch,
-        bobResult4.encryptedKeys,
-        base64.encode(bobResult4.ciphertext!),
-      ),
-    );
-
-    expect(aliceResult4.error, null);
-    expect(aliceResult4.payload, "That's okay.");
-  });
-
-  test('Test resending key exchanges', () async {
-    const aliceJid = 'alice@server1';
-    const bobJid = 'bob@server2';
-
-    final aliceDevice = await OmemoDevice.generateNewDevice(aliceJid, opkAmount: 1);
-    final bobDevice = await OmemoDevice.generateNewDevice(bobJid, opkAmount: 1);
-
-    final aliceManager = OmemoManager(
-      aliceDevice,
-      AlwaysTrustingTrustManager(),
-      (result, recipientJid) async {},
-      (jid) async {
-        expect(jid, bobJid);
-        return [ bobDevice.id ];
-      },
-      (jid, id) async {
-        expect(jid, bobJid);
-        return bobDevice.toBundle();
-      },
-      (jid) async {},
-    );
-    final bobManager = OmemoManager(
-      bobDevice,
-      AlwaysTrustingTrustManager(),
-      (result, recipientJid) async {},
-      (jid) async {
-        expect(jid, aliceJid);
-        return [aliceDevice.id];
-      },
-      (jid, id) async {
-        expect(jid, aliceJid);
-        return aliceDevice.toBundle();
-      },
-      (jid) async {},
-    );
-    
-    // Alice sends Bob a message
-    final aliceResult1 = await aliceManager.onOutgoingStanza(
-      const OmemoOutgoingStanza(
-        [bobJid],
-        'Hello World!',
-      ),
-    );
-
-    // The first message must be a KEX message
-    expect(aliceResult1.encryptedKeys.first.kex, true);
-
-    // Bob decrypts Alice's message
-    final bobResult1 = await bobManager.onIncomingStanza(
-      OmemoIncomingStanza(
-        aliceJid,
-        aliceDevice.id,
-        DateTime.now().millisecondsSinceEpoch,
-        aliceResult1.encryptedKeys,
-        base64.encode(aliceResult1.ciphertext!),
-      ),
-    );
-    expect(bobResult1.error, null);
-    expect(bobResult1.payload, 'Hello World!');
-
-    // Alice immediately sends another message 
     final aliceResult2 = await aliceManager.onOutgoingStanza(
       const OmemoOutgoingStanza(
         [bobJid],
-        'Hello Bob',
+        'I did not trust your last device, Bob!',
       ),
     );
 
-    // The response should contain a KEX
+    // Bob decrypts it
-    expect(aliceResult2.encryptedKeys.first.kex, true);
-
-    // The basic data should be the same
-    final parsedFirstKex = OmemoKeyExchange.fromBuffer(
-      base64.decode(aliceResult1.encryptedKeys.first.value),
-    );
-    final parsedSecondKex = OmemoKeyExchange.fromBuffer(
-      base64.decode(aliceResult2.encryptedKeys.first.value),
-    );
-    expect(parsedSecondKex.pkId, parsedFirstKex.pkId);
-    expect(parsedSecondKex.spkId, parsedFirstKex.spkId);
-    expect(parsedSecondKex.ik, parsedFirstKex.ik);
-    expect(parsedSecondKex.ek, parsedFirstKex.ek);
-
-    // Alice decrypts it
     final bobResult2 = await bobManager.onIncomingStanza(
       OmemoIncomingStanza(
         aliceJid,
@@ -1296,58 +1022,7 @@ void main() {
         base64.encode(aliceResult2.ciphertext!),
       ),
     );
-    expect(bobResult2.error, null);
-    expect(bobResult2.payload, 'Hello Bob');
 
-    // Bob also sends a message
+    expect(bobResult2.payload, 'I did not trust your last device, Bob!');
-    final bobResult3 = await bobManager.onOutgoingStanza(
-      const OmemoOutgoingStanza(
-        [aliceJid],
-        'Hello Alice!',
-      ),
-    );
-
-    // Alice decrypts it
-    final aliceResult3 = await aliceManager.onIncomingStanza(
-      OmemoIncomingStanza(
-        bobJid,
-        bobDevice.id,
-        DateTime.now().millisecondsSinceEpoch,
-        bobResult3.encryptedKeys,
-        base64.encode(bobResult3.ciphertext!),
-      ),
-    );
-    expect(aliceResult3.error, null);
-    expect(aliceResult3.payload, 'Hello Alice!'); 
-    
-    // Bob now acks the ratchet
-    await aliceManager.ratchetAcknowledged(
-      bobJid,
-      bobDevice.id,
-    );
-
-    // Alice replies
-    final aliceResult4 = await aliceManager.onOutgoingStanza(
-      const OmemoOutgoingStanza(
-        [bobJid],
-        'Hi Bob',
-      ),
-    );
-
-    // The response should contain no KEX
-    expect(aliceResult4.encryptedKeys.first.kex, false);
-
-    // Bob decrypts it
-    final bobResult4 = await bobManager.onIncomingStanza(
-      OmemoIncomingStanza(
-        aliceJid,
-        aliceDevice.id,
-        DateTime.now().millisecondsSinceEpoch,
-        aliceResult4.encryptedKeys,
-        base64.encode(aliceResult4.ciphertext!),
-      ),
-    );
-    expect(bobResult4.error, null);
-    expect(bobResult4.payload, 'Hi Bob');
   });
 }