tink android side

android/app/build.gradle

@@ -48,6 +48,7 @@ android {
         targetSdkVersion flutter.targetSdkVersion
         versionCode flutterVersionCode.toInteger()
         versionName flutterVersionName
+        multiDexEnabled true
     }
 
     buildTypes {
@@ -65,4 +66,10 @@ flutter {
 
 dependencies {
     implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
+    implementation "androidx.multidex:multidex:2.0.1"
+
+    implementation "com.google.crypto.tink:tink-android:1.6.1"
+
+    implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-core:1.6.0'
+    implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-android:1.6.0'
 }

android/app/src/main/AndroidManifest.xml

@@ -1,37 +1,36 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
-          package="com.hoc.node_auth">
+    package="com.hoc.node_auth">
 
-    <uses-permission android:name="android.permission.INTERNET"/>
+    <uses-permission android:name="android.permission.INTERNET" />
 
     <application
-            android:label="node_auth"
-            android:name="${applicationName}"
-            android:icon="@mipmap/ic_launcher">
+        android:name=".MyApp"
+        android:icon="@mipmap/ic_launcher"
+        android:label="node_auth">
         <activity
-                android:name=".MainActivity"
-                android:exported="true"
-                android:launchMode="singleTop"
-                android:theme="@style/LaunchTheme"
-                android:configChanges="orientation|keyboardHidden|keyboard|screenSize|smallestScreenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
-                android:hardwareAccelerated="true"
-                android:windowSoftInputMode="adjustResize">
+            android:name=".MainActivity"
+            android:configChanges="orientation|keyboardHidden|keyboard|screenSize|smallestScreenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
+            android:exported="true"
+            android:hardwareAccelerated="true"
+            android:launchMode="singleTop"
+            android:theme="@style/LaunchTheme"
+            android:windowSoftInputMode="adjustResize">
             <!-- Specifies an Android theme to apply to this Activity as soon as
                  the Android process has started. This theme is visible to the user
                  while the Flutter UI initializes. After that, this theme continues
                  to determine the Window background behind the Flutter UI. -->
             <meta-data
-                    android:name="io.flutter.embedding.android.NormalTheme"
-                    android:resource="@style/NormalTheme"
-            />
+                android:name="io.flutter.embedding.android.NormalTheme"
+                android:resource="@style/NormalTheme" />
             <intent-filter>
-                <action android:name="android.intent.action.MAIN"/>
-                <category android:name="android.intent.category.LAUNCHER"/>
+                <action android:name="android.intent.action.MAIN" />
+                <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
         <!-- Don't delete the meta-data below.
              This is used by the Flutter tool to generate GeneratedPluginRegistrant.java -->
         <meta-data
-                android:name="flutterEmbedding"
-                android:value="2"/>
+            android:name="flutterEmbedding"
+            android:value="2" />
     </application>
 </manifest>

android/app/src/main/kotlin/com/hoc/node_auth/MainActivity.kt

@@ -1,6 +1,107 @@
 package com.hoc.node_auth
 
+import android.util.Log
+import com.google.crypto.tink.subtle.Base64
 import io.flutter.embedding.android.FlutterActivity
+import io.flutter.embedding.engine.FlutterEngine
+import io.flutter.plugin.common.MethodCall
+import io.flutter.plugin.common.MethodChannel
+import kotlinx.coroutines.*
 
-class MainActivity: FlutterActivity() {
+class MainActivity : FlutterActivity() {
+  private lateinit var cryptoChannel: MethodChannel
+  private lateinit var mainScope: CoroutineScope
+
+  //region Lifecycle
+  override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
+    super.configureFlutterEngine(flutterEngine)
+    Log.d("Flutter", "configureFlutterEngine flutterEngine=$flutterEngine $this")
+
+    mainScope = MainScope()
+    cryptoChannel = MethodChannel(
+      flutterEngine.dartExecutor.binaryMessenger,
+      CRYPTO_CHANNEL,
+    ).apply { setMethodCallHandler(MethodCallHandlerImpl()) }
+  }
+
+  override fun cleanUpFlutterEngine(flutterEngine: FlutterEngine) {
+    super.cleanUpFlutterEngine(flutterEngine)
+    Log.d("Flutter", "cleanUpFlutterEngine flutterEngine=$flutterEngine $this")
+
+    cryptoChannel.setMethodCallHandler(null)
+    mainScope.cancel()
+  }
+  //endregion
+
+  private inner class MethodCallHandlerImpl : MethodChannel.MethodCallHandler {
+    override fun onMethodCall(call: MethodCall, result: MethodChannel.Result) {
+      when (call.method) {
+        ENCRYPT_METHOD -> encrypt(call, result)
+        DECRYPT_METHOD -> decrypt(call, result)
+        else -> result.notImplemented()
+      }
+    }
+  }
+
+  //region Handlers
+  private fun encrypt(
+    call: MethodCall,
+    result: MethodChannel.Result
+  ) {
+    val plaintext = checkNotNull(call.arguments<String?>()) { "plaintext must be not null" }
+
+    mainScope.launch {
+      runCatching {
+        withContext(Dispatchers.IO) {
+          plaintext
+            .encodeToByteArray()
+            .let { myApp.aead.encrypt(it, null) }
+            .let { Base64.encode(it) }
+        }
+      }
+        .onSuccess { result.success(it) }
+        .onFailureExceptCancellationException {
+          Log.e("Flutter", "encrypt", it)
+          result.error(CRYPTO_ERROR_CODE, it.message, null)
+        }
+    }
+  }
+
+  private fun decrypt(
+    call: MethodCall,
+    result: MethodChannel.Result
+  ) {
+    val ciphertext = checkNotNull(call.arguments<String?>()) { "ciphertext must be not null" }
+
+    mainScope.launch {
+      runCatching {
+        withContext(Dispatchers.IO) {
+          Base64
+            .decode(ciphertext, Base64.DEFAULT)
+            .let { myApp.aead.decrypt(it, null) }
+            .decodeToString()
+        }
+      }
+        .onSuccess { result.success(it) }
+        .onFailureExceptCancellationException {
+          Log.e("Flutter", "decrypt", it)
+          result.error(CRYPTO_ERROR_CODE, it.message, null)
+        }
+    }
+  }
+  //endregion
+
+  private companion object {
+    const val CRYPTO_CHANNEL = "com.hoc.node_auth/crypto"
+    const val CRYPTO_ERROR_CODE = "com.hoc.node_auth/crypto_error"
+    const val ENCRYPT_METHOD = "encrypt"
+    const val DECRYPT_METHOD = "decrypt"
+  }
 }
+
+private inline fun <T> Result<T>.onFailureExceptCancellationException(action: (throwable: Throwable) -> Unit): Result<T> {
+  return onFailure {
+    if (it is CancellationException) throw it
+    action(it)
+  }
+}

android/app/src/main/kotlin/com/hoc/node_auth/MyApp.kt

@@ -0,0 +1,37 @@
+package com.hoc.node_auth
+
+import android.app.Activity
+import androidx.multidex.MultiDex
+import com.google.crypto.tink.Aead
+import com.google.crypto.tink.KeyTemplates
+import com.google.crypto.tink.aead.AeadConfig
+import com.google.crypto.tink.integration.android.AndroidKeysetManager
+import com.google.crypto.tink.integration.android.AndroidKeystoreKmsClient
+import io.flutter.app.FlutterApplication
+
+class MyApp : FlutterApplication() {
+  val aead: Aead by lazy {
+    AndroidKeysetManager
+      .Builder()
+      .withSharedPref(this, KEYSET_NAME, PREF_FILE_NAME)
+      .withKeyTemplate(KeyTemplates.get("AES256_GCM"))
+      .withMasterKeyUri(MASTER_KEY_URI)
+      .build()
+      .keysetHandle
+      .getPrimitive(Aead::class.java)
+  }
+
+  override fun onCreate() {
+    super.onCreate()
+    MultiDex.install(this)
+    AeadConfig.register()
+  }
+
+  private companion object {
+    private const val KEYSET_NAME = "nodeauth_keyset"
+    private const val PREF_FILE_NAME = "nodeauth_pref"
+    private const val MASTER_KEY_URI = "${AndroidKeystoreKmsClient.PREFIX}nodeauth_master_key"
+  }
+}
+
+val Activity.myApp: MyApp get() = application as MyApp

lib/data/local/local_data_source.dart

@@ -15,3 +15,9 @@ abstract class LocalDataSource {
   /// Throws [LocalDataSourceException] if removing is failed
   Future<void> removeUserAndToken();
 }
+
+abstract class Crypto {
+  Future<String> encrypt(String plaintext);
+
+  Future<String> decrypt(String ciphertext);
+}

lib/data/local/method_channel_crypto_impl.dart

@@ -0,0 +1,27 @@
+import 'package:flutter/services.dart';
+import 'package:node_auth/data/exception/local_data_source_exception.dart';
+import 'package:node_auth/data/local/local_data_source.dart';
+
+class MethodChannelCryptoImpl implements Crypto {
+  static const cryptoChannel = 'com.hoc.node_auth/crypto';
+  static const cryptoErrorCode = 'com.hoc.node_auth/crypto_error';
+  static const encryptMethod = 'encrypt';
+  static const decryptMethod = 'decrypt';
+  static const MethodChannel channel = MethodChannel(cryptoChannel);
+
+  @override
+  Future<String> encrypt(String plaintext) => channel
+      .invokeMethod<String>(encryptMethod, plaintext)
+      .then((v) => v!)
+      .onError<MissingPluginException>((e, s) => plaintext)
+      .onError<Object>((e, s) =>
+          throw LocalDataSourceException('Cannot encrypt the plaintext', e, s));
+
+  @override
+  Future<String> decrypt(String ciphertext) => channel
+      .invokeMethod<String>(decryptMethod, ciphertext)
+      .then((v) => v!)
+      .onError<MissingPluginException>((e, s) => ciphertext)
+      .onError<Object>((e, s) => throw LocalDataSourceException(
+          'Cannot decrypt the ciphertext', e, s));
+}

lib/data/local/shared_pref_util.dart

@@ -1,3 +1,4 @@
+import 'dart:async';
 import 'dart:convert';
 
 import 'package:node_auth/data/exception/local_data_source_exception.dart';
@@ -9,8 +10,9 @@ import 'package:rxdart/rxdart.dart';
 class SharedPrefUtil implements LocalDataSource {
   static const _kUserTokenKey = 'com.hoc.node_auth_flutter.user_and_token';
   final RxSharedPreferences _rxPrefs;
+  final Crypto _crypto;
 
-  const SharedPrefUtil(this._rxPrefs);
+  const SharedPrefUtil(this._rxPrefs, this._crypto);
 
   @override
   Future<void> removeUserAndToken() =>
@@ -37,10 +39,17 @@ class SharedPrefUtil implements LocalDataSource {
       .onErrorReturnWith((e, s) =>
           throw LocalDataSourceException('Cannot read user and token', e, s));
 
-  static UserAndTokenEntity? _toEntity(dynamic jsonString) => jsonString == null
-      ? null
-      : UserAndTokenEntity.fromJson(json.decode(jsonString));
+  //
+  // Encoder and Decoder
+  //
 
-  static String? _toString(UserAndTokenEntity? entity) =>
-      entity == null ? null : jsonEncode(entity);
+  FutureOr<UserAndTokenEntity?> _toEntity(dynamic jsonString) =>
+      jsonString == null
+          ? null
+          : _crypto
+              .decrypt(jsonString as String)
+              .then((s) => UserAndTokenEntity.fromJson(jsonDecode(s)));
+
+  FutureOr<String?> _toString(UserAndTokenEntity? entity) =>
+      entity == null ? null : _crypto.encrypt(jsonEncode(entity));
 }

lib/main.dart

@@ -7,6 +7,7 @@ import 'package:flutter_bloc_pattern/flutter_bloc_pattern.dart';
 import 'package:flutter_provider/flutter_provider.dart';
 import 'package:node_auth/app.dart';
 import 'package:node_auth/data/local/local_data_source.dart';
+import 'package:node_auth/data/local/method_channel_crypto_impl.dart';
 import 'package:node_auth/data/local/shared_pref_util.dart';
 import 'package:node_auth/data/remote/api_service.dart';
 import 'package:node_auth/data/remote/remote_data_source.dart';
@@ -25,7 +26,8 @@ void main() async {
 
   // construct LocalDataSource
   final rxPrefs = RxSharedPreferences.getInstance();
-  final LocalDataSource localDataSource = SharedPrefUtil(rxPrefs);
+  final crypto = MethodChannelCryptoImpl();
+  final LocalDataSource localDataSource = SharedPrefUtil(rxPrefs, crypto);
 
   // construct UserRepository
   final UserRepository userRepository = UserRepositoryImpl(

pubspec.lock

@@ -495,16 +495,20 @@ packages:
   rx_shared_preferences:
     dependency: "direct main"
     description:
-      name: rx_shared_preferences
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "2.3.0"
+      path: "."
+      ref: "78db985d06f275ebf3f12aa21511cfc7333c220b"
+      resolved-ref: "78db985d06f275ebf3f12aa21511cfc7333c220b"
+      url: "https://github.com/hoc081098/rx_shared_preferences.git"
+    source: git
+    version: "3.0.0-dev.0"
   rx_storage:
-    dependency: transitive
+    dependency: "direct overridden"
     description:
-      name: rx_storage
-      url: "https://pub.dartlang.org"
-    source: hosted
+      path: "."
+      ref: "50c711605b6aa9a185e7f3ca9b2c87f0d2b35187"
+      resolved-ref: "50c711605b6aa9a185e7f3ca9b2c87f0d2b35187"
+      url: "https://github.com/Flutter-Dart-Open-Source/rx_storage.git"
+    source: git
     version: "1.2.0"
   rxdart:
     dependency: "direct main"

pubspec.yaml

@@ -46,3 +46,12 @@ flutter:
     - assets/bg.jpg
     - assets/user.png
 
+dependency_overrides:
+  rx_shared_preferences:
+    git:
+      url: https://github.com/hoc081098/rx_shared_preferences.git
+      ref: 78db985d06f275ebf3f12aa21511cfc7333c220b
+  rx_storage:
+    git:
+      url: https://github.com/Flutter-Dart-Open-Source/rx_storage.git
+      ref: 50c711605b6aa9a185e7f3ca9b2c87f0d2b35187