feat: Allow serialising Device to Json

lib/omemo_dart.dart

@@ -6,5 +6,6 @@ export 'src/events.dart';
 export 'src/helpers.dart';
 export 'src/keys.dart';
 export 'src/omemo/bundle.dart';
+export 'src/omemo/device.dart';
 export 'src/omemo/sessionmanager.dart';
 export 'src/x3dh/x3dh.dart';

lib/src/keys.dart

@@ -1,5 +1,7 @@
 import 'dart:convert';
 import 'package:cryptography/cryptography.dart';
+import 'package:meta/meta.dart';
+import 'package:omemo_dart/src/helpers.dart';
 import 'package:pinenacl/api.dart';
 import 'package:pinenacl/tweetnacl.dart';
 
@@ -43,11 +45,13 @@ class OmemoPublicKey {
 
   SimplePublicKey asPublicKey() => _pubkey;
 
-  /// Convert the public key into a [SimpleKeyPairData] with a stub private key. Useful
-  /// for when cryptography calls for a KeyPair, but only uses the public key.
-  //SimpleKeyPairData asPseudoKeypair() {
-  //
-  //}
+  @visibleForTesting
+  Future<bool> equals(OmemoPublicKey key) async {
+    return type == key.type && listsEqual(
+      await getBytes(),
+      await key.getBytes(),
+    );
+  }
 }
 
 class OmemoPrivateKey {
@@ -69,16 +73,39 @@ class OmemoPrivateKey {
 
     return OmemoPrivateKey(List<int>.from(skc), KeyPairType.x25519);
   }
+
+  @visibleForTesting
+  Future<bool> equals(OmemoPrivateKey key) async {
+    return type == key.type && listsEqual(
+      await getBytes(),
+      await key.getBytes(),
+    );
+  }
 }
 
 /// A generic wrapper class for both Ed25519 and X25519 keypairs
 class OmemoKeyPair {
 
   const OmemoKeyPair(this.pk, this.sk, this.type);
-  final KeyPairType type;
-  final OmemoPublicKey pk;
-  final OmemoPrivateKey sk;
 
+  /// Create an OmemoKeyPair just from a [type] and the bytes of the private and public
+  /// key.
+  factory OmemoKeyPair.fromBytes(List<int> publicKey, List<int> privateKey, KeyPairType type) {
+    return OmemoKeyPair(
+      OmemoPublicKey.fromBytes(
+        publicKey,
+        type,
+      ),
+      OmemoPrivateKey(
+        privateKey,
+        type,
+      ),
+      type,
+    );
+  }
+
+  /// Generate a completely new random OmemoKeyPair of type [type]. [type] must be either
+  /// KeyPairType.ed25519 or KeyPairType.x25519.
   static Future<OmemoKeyPair> generateNewPair(KeyPairType type) async {
     assert(type == KeyPairType.ed25519 || type == KeyPairType.x25519, 'Keypair must be either Ed25519 or X25519');
 
@@ -103,6 +130,10 @@ class OmemoKeyPair {
     );
   }
 
+  final KeyPairType type;
+  final OmemoPublicKey pk;
+  final OmemoPrivateKey sk;
+  
   /// Return the bytes that comprise the public key.
   Future<OmemoKeyPair> toCurve25519() async {
     assert(type == KeyPairType.ed25519, 'Cannot convert non-Ed25519 keypair to X25519');
@@ -121,4 +152,11 @@ class OmemoKeyPair {
       type: type,
     );
   }
+
+  @visibleForTesting
+  Future<bool> equals(OmemoKeyPair pair) async {
+    return type == pair.type &&
+      await pk.equals(pair.pk) &&
+      await sk.equals(pair.sk);
+  }
 }

lib/src/omemo/device.dart

@@ -12,6 +12,56 @@ class Device {
 
   const Device(this.id, this.ik, this.spk, this.spkId, this.spkSignature, this.opks);
 
+  /// Deserialize the Device
+  factory Device.fromJson(Map<String, dynamic> data) {
+    // NOTE: We use the way OpenSSH names their keys, meaning that ik is the Identity
+    //       Keypair's private key, while ik_pub refers to the Identity Keypair's public
+    //       key.
+    /*
+    {
+      'id': 123,
+      'ik': 'base/64/encoded',
+      'ik_pub': 'base/64/encoded',
+      'spk': 'base/64/encoded',
+      'spk_pub': 'base/64/encoded',
+      'spk_id': 123,
+      'spk_sig': 'base/64/encoded',
+      'opks': [
+        {
+          'id': 0,
+          'public': 'base/64/encoded',
+          'private': 'base/64/encoded'
+        }, ...
+      ]
+    }
+    */
+    final opks = <int, OmemoKeyPair>{};
+    for (final opk in data['opks']! as List<Map<String, dynamic>>) {
+      opks[opk['id']! as int] = OmemoKeyPair.fromBytes(
+        base64.decode(opk['public']! as String),
+        base64.decode(opk['private']! as String),
+        KeyPairType.x25519,
+      );
+    }
+
+    return Device(
+      data['id']! as int,
+      OmemoKeyPair.fromBytes(
+        base64.decode(data['ik_pub']! as String),
+        base64.decode(data['ik']! as String),
+        KeyPairType.ed25519,
+      ),
+      OmemoKeyPair.fromBytes(
+        base64.decode(data['spk_pub']! as String),
+        base64.decode(data['spk']! as String),
+        KeyPairType.x25519,
+      ),
+      data['spk_id']! as int,
+      base64.decode(data['spk_sig']! as String),
+      opks,
+    );
+  }
+  
   /// Generate a completely new device, i.e. cryptographic identity.
   static Future<Device> generateNewDevice({ int opkAmount = 100 }) async {
     final id = generateRandom32BitNumber();
@@ -92,4 +142,28 @@ class Device {
       encodedOpks,
     );
   }
+
+  /// Serialise the device information.
+  Future<Map<String, dynamic>> toJson() async {
+    /// Serialise the OPKs
+    final serialisedOpks = List<Map<String, dynamic>>.empty(growable: true);
+    for (final entry in opks.entries) {
+      serialisedOpks.add({
+        'id': entry.key,
+        'public': base64.encode(await entry.value.pk.getBytes()),
+        'private': base64.encode(await entry.value.sk.getBytes()),
+      });
+    }
+    
+    return {
+      'id': id,
+      'ik': base64.encode(await ik.sk.getBytes()),
+      'ik_pub': base64.encode(await ik.pk.getBytes()),
+      'spk': base64.encode(await spk.sk.getBytes()),
+      'spk_pub': base64.encode(await spk.pk.getBytes()),
+      'spk_id': spkId,
+      'spk_sig': base64.encode(spkSignature),
+      'opks': serialisedOpks,
+    };
+  }
 }

test/serialisation_test.dart

@@ -0,0 +1,24 @@
+import 'package:omemo_dart/omemo_dart.dart';
+import 'package:test/test.dart';
+
+void main() {
+  test('Test serialising and deserialising Device', () async {
+    // Generate a random session
+    final oldSession = await OmemoSessionManager.generateNewIdentity(opkAmount: 1);
+    final oldDevice = await oldSession.getDevice();
+    final serialised = await oldDevice.toJson();
+
+    final newDevice = Device.fromJson(serialised);
+    expect(oldDevice.id, newDevice.id);
+    expect(await oldDevice.ik.equals(newDevice.ik), true);
+    expect(await oldDevice.spk.equals(newDevice.spk), true);
+    expect(listsEqual(oldDevice.spkSignature, newDevice.spkSignature), true);
+    expect(oldDevice.spkId, newDevice.spkId);
+
+    // Check the Ontime-Prekeys
+    expect(oldDevice.opks.length, newDevice.opks.length);
+    for (final entry in oldDevice.opks.entries) {
+      expect(await newDevice.opks[entry.key]!.equals(entry.value), true);
+    }
+  });
+}