feat: decrypt screenshot in isolate

diyews · Nov 22, 2021 · 403eddb · 403eddb
1 parent 0e77b14
commit 403eddb
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Showing 3 changed files with 72 additions and 10 deletions.
diff --git a/lib/cbc_cipher.dart b/lib/cbc_cipher.dart
@@ -1,3 +1,4 @@
+import 'dart:isolate';
 import 'dart:typed_data';
 
 import 'package:pointycastle/export.dart' hide State;
@@ -6,14 +7,29 @@ import 'package:shared_preferences/shared_preferences.dart';
 class CBCCipher {
   static Uint8List aesKey = Uint8List(0);
 
+  static void setAESKey(Uint8List key, [bool isSync = true]) {
+    aesKey = key;
+    if (isSync) {
+      CBCCipherIsolate.syncKey();
+    }
+  }
+
   static Future<void> initKey() async {
     final prefs = await SharedPreferences.getInstance();
     final key = prefs.getString('encrypt_key') ?? '';
     if (key.isNotEmpty) {
-      aesKey = Uint8List.fromList(key.codeUnits);
+      setAESKey(Uint8List.fromList(key.codeUnits));
     }
   }
 
+  static Future<void> initIsolate() async {
+    final receivePort = ReceivePort();
+    await Isolate.spawn(_handler, receivePort.sendPort);
+    final sendPort = await receivePort.first;
+    CBCCipherIsolate.initSendPort(sendPort);
+    await CBCCipherIsolate.syncKey();
+  }
+
   static Uint8List processBodyBytes(Uint8List bodyBytes) {
     final iv = Uint8List.sublistView(bodyBytes, 0, aesKey.length);
     final cipherText = Uint8List.sublistView(bodyBytes, aesKey.length);
@@ -33,3 +49,51 @@ class CBCCipher {
         paddedPlainText, 0, paddedPlainText.length - paddedPlainText.last);
   }
 }
+
+class CBCCipherIsolate {
+  static SendPort? _sendPort;
+
+  static initSendPort(SendPort sendPort) {
+    _sendPort = sendPort;
+  }
+
+  static Future syncKey() {
+    return _send(_sendPort!, {'type': 'update_key', 'data': CBCCipher.aesKey});
+  }
+
+  static Future processBodyBytesIsolate(Uint8List bodyBytes) {
+    return _send(_sendPort!, {'type': 'decrypt', 'data': bodyBytes});
+  }
+}
+
+Future _send(SendPort port, msg) {
+  final response = ReceivePort();
+  port.send([msg, response.sendPort]);
+  return response.first;
+}
+
+Future<void> _handler(SendPort sendPort) async {
+  final port = ReceivePort();
+  sendPort.send(port.sendPort);
+
+  await for (var msg in port) {
+    final request = msg[0];
+    SendPort replyTo = msg[1];
+
+    switch (request['type']) {
+      case 'update_key':
+        CBCCipher.setAESKey(request['data'], false);
+        replyTo.send('Done');
+        break;
+      case 'decrypt':
+        final decrypted = CBCCipher.processBodyBytes(request['data']);
+        replyTo.send(decrypted);
+        break;
+      case 'test':
+        replyTo.send('Done');
+        break;
+      default:
+        replyTo.send('Done');
+    }
+  }
+}
diff --git a/lib/main.dart b/lib/main.dart
@@ -10,6 +10,7 @@ import 'package:shared_preferences/shared_preferences.dart';
 
 void main() async {
   WidgetsFlutterBinding.ensureInitialized();
+  await CBCCipher.initIsolate();
   await CBCCipher.initKey();
   runApp(const MyApp());
 }
@@ -34,16 +35,14 @@ class MyApp extends StatelessWidget {
         // is not restarted.
         primarySwatch: Colors.blue,
       ),
-      home: MyHomePage(),
+      home: const MyHomePage(),
       debugShowCheckedModeBanner: false,
     );
   }
 }
 
 class MyHomePage extends StatefulWidget {
-  MyHomePage({Key? key}) : super(key: key) {
-    CBCCipher.initKey();
-  }
+  const MyHomePage({Key? key}) : super(key: key);
 
   // This widget is the home page of your application. It is stateful, meaning
   // that it has a State object (defined below) that contains fields that affect
@@ -171,8 +170,8 @@ Future<String> _openEditEncryptKeyDialog(BuildContext context) async {
               onPressed: () {
                 final text = _controller.text;
                 prefs.setString('encrypt_key', text);
-                CBCCipher.aesKey = Uint8List.fromList(text.codeUnits);
-                Navigator.of(context).pop(_controller.text);
+                CBCCipher.setAESKey(Uint8List.fromList(text.codeUnits));
+                Navigator.of(context).pop(text);
               },
               child: const Text('OK')),
         ],

diff --git a/lib/scrcpy.dart b/lib/scrcpy.dart
@@ -306,9 +306,8 @@ class _ScreenShotState extends State<_ScreenShot> {
       running = false;
       return;
     }
-    setState(() {
-      imageBytes = CBCCipher.processBodyBytes(res.bodyBytes);
-    });
+    imageBytes = await CBCCipherIsolate.processBodyBytesIsolate(res.bodyBytes);
+    setState(() {});
     running = false;
     if (widget.screenShotModel.mode == _ScreenShotMode.one) {
       return;