feat: E2EE for data channel.

Author: cloudwebrtc

lib/src/e2ee/data_channel.dart

@@ -0,0 +1,51 @@
+import 'dart:typed_data';
+
+import 'package:cryptography/cryptography.dart';
+
+import 'key_provider.dart';
+
+class DataChannelFrameCryptor {
+  final KeyProvider keyProvider;
+  final algorithm = AesGcm.with128bits();
+  late SecretKey secretKey;
+  late List<int> nonce;
+
+  DataChannelFrameCryptor(
+    this.keyProvider,
+  );
+
+  Future<void> init() async {
+    // Generate a secret key
+    secretKey = await algorithm
+        .newSecretKeyFromBytes(await keyProvider.exportSharedKey());
+    print('Secret key: $secretKey');
+
+    // Generate a nonce
+    nonce = algorithm.newNonce();
+    print('Nonce: $nonce');
+  }
+
+  /// Encrypt
+  Future<Uint8List> encrypt(Uint8List frame) async {
+    final secretBox = await algorithm.encrypt(
+      frame,
+      secretKey: secretKey,
+      nonce: nonce,
+    );
+
+    ///print('Nonce: ${secretBox.nonce}');
+    ///print('Ciphertext: ${secretBox.cipherText}');
+    ///print('MAC: ${secretBox.mac.bytes}');
+    return Uint8List.fromList(secretBox.cipherText);
+  }
+
+  /// Decrypt
+  Future<Uint8List?> decrypt(Uint8List secretBox) async {
+    final clearText = await algorithm.encrypt(
+      secretBox,
+      secretKey: secretKey,
+    );
+    //print('Cleartext: $clearText');
+    return Uint8List.fromList(clearText.cipherText);
+  }
+}

pubspec.yaml

@@ -44,6 +44,7 @@ dependencies:
   dart_webrtc: ^1.4.9
   sdp_transform: ^0.3.2
   web: ^1.0.0
+  cryptography: ^2.7.0
 
 dev_dependencies:
   flutter_test: