meta: Implement access to AES encryption (but fast)

example/.gitignore

@@ -0,0 +1,47 @@
+# Miscellaneous
+*.class
+*.log
+*.pyc
+*.swp
+.DS_Store
+.atom/
+.buildlog/
+.history
+.svn/
+migrate_working_dir/
+
+# IntelliJ related
+*.iml
+*.ipr
+*.iws
+.idea/
+
+# The .vscode folder contains launch configuration and tasks you configure in
+# VS Code which you may wish to be included in version control, so this line
+# is commented out by default.
+#.vscode/
+
+# Flutter/Dart/Pub related
+**/doc/api/
+**/ios/Flutter/.last_build_id
+.dart_tool/
+.flutter-plugins
+.flutter-plugins-dependencies
+.packages
+.pub-cache/
+.pub/
+/build/
+
+# Web related
+lib/generated_plugin_registrant.dart
+
+# Symbolication related
+app.*.symbols
+
+# Obfuscation related
+app.*.map.json
+
+# Android Studio will place build artifacts here
+/android/app/debug
+/android/app/profile
+/android/app/release

example/.metadata

@@ -0,0 +1,30 @@
+# This file tracks properties of this Flutter project.
+# Used by Flutter tool to assess capabilities and perform upgrades etc.
+#
+# This file should be version controlled.
+
+version:
+  revision: 85684f9300908116a78138ea4c6036c35c9a1236
+  channel: stable
+
+project_type: app
+
+# Tracks metadata for the flutter migrate command
+migration:
+  platforms:
+    - platform: root
+      create_revision: 85684f9300908116a78138ea4c6036c35c9a1236
+      base_revision: 85684f9300908116a78138ea4c6036c35c9a1236
+    - platform: android
+      create_revision: 85684f9300908116a78138ea4c6036c35c9a1236
+      base_revision: 85684f9300908116a78138ea4c6036c35c9a1236
+
+  # User provided section
+
+  # List of Local paths (relative to this file) that should be
+  # ignored by the migrate tool.
+  #
+  # Files that are not part of the templates will be ignored by default.
+  unmanaged_files:
+    - 'lib/main.dart'
+    - 'ios/Runner.xcodeproj/project.pbxproj'

example/README.md

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+# example
+
+A new Flutter project.
+
+## Getting Started
+
+This project is a starting point for a Flutter application.
+
+A few resources to get you started if this is your first Flutter project:
+
+- [Lab: Write your first Flutter app](https://docs.flutter.dev/get-started/codelab)
+- [Cookbook: Useful Flutter samples](https://docs.flutter.dev/cookbook)
+
+For help getting started with Flutter development, view the
+[online documentation](https://docs.flutter.dev/), which offers tutorials,
+samples, guidance on mobile development, and a full API reference.

example/analysis_options.yaml

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+# This file configures the analyzer, which statically analyzes Dart code to
+# check for errors, warnings, and lints.
+#
+# The issues identified by the analyzer are surfaced in the UI of Dart-enabled
+# IDEs (https://dart.dev/tools#ides-and-editors). The analyzer can also be
+# invoked from the command line by running `flutter analyze`.
+
+# The following line activates a set of recommended lints for Flutter apps,
+# packages, and plugins designed to encourage good coding practices.
+include: package:flutter_lints/flutter.yaml
+
+linter:
+  # The lint rules applied to this project can be customized in the
+  # section below to disable rules from the `package:flutter_lints/flutter.yaml`
+  # included above or to enable additional rules. A list of all available lints
+  # and their documentation is published at
+  # https://dart-lang.github.io/linter/lints/index.html.
+  #
+  # Instead of disabling a lint rule for the entire project in the
+  # section below, it can also be suppressed for a single line of code
+  # or a specific dart file by using the `// ignore: name_of_lint` and
+  # `// ignore_for_file: name_of_lint` syntax on the line or in the file
+  # producing the lint.
+  rules:
+    # avoid_print: false  # Uncomment to disable the `avoid_print` rule
+    # prefer_single_quotes: true  # Uncomment to enable the `prefer_single_quotes` rule
+
+# Additional information about this file can be found at
+# https://dart.dev/guides/language/analysis-options

example/android/.gitignore

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+gradle-wrapper.jar
+/.gradle
+/captures/
+/gradlew
+/gradlew.bat
+/local.properties
+GeneratedPluginRegistrant.java
+
+# Remember to never publicly share your keystore.
+# See https://flutter.dev/docs/deployment/android#reference-the-keystore-from-the-app
+key.properties
+**/*.keystore
+**/*.jks

example/android/app/build.gradle

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+def localProperties = new Properties()
+def localPropertiesFile = rootProject.file('local.properties')
+if (localPropertiesFile.exists()) {
+    localPropertiesFile.withReader('UTF-8') { reader ->
+        localProperties.load(reader)
+    }
+}
+
+def flutterRoot = localProperties.getProperty('flutter.sdk')
+if (flutterRoot == null) {
+    throw new GradleException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")
+}
+
+def flutterVersionCode = localProperties.getProperty('flutter.versionCode')
+if (flutterVersionCode == null) {
+    flutterVersionCode = '1'
+}
+
+def flutterVersionName = localProperties.getProperty('flutter.versionName')
+if (flutterVersionName == null) {
+    flutterVersionName = '1.0'
+}
+
+apply plugin: 'com.android.application'
+apply plugin: 'kotlin-android'
+apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"
+
+android {
+    compileSdkVersion 33
+    ndkVersion flutter.ndkVersion
+
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
+    }
+
+    kotlinOptions {
+        jvmTarget = '1.8'
+    }
+
+    sourceSets {
+        main.java.srcDirs += 'src/main/kotlin'
+    }
+
+    defaultConfig {
+        // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
+        applicationId "com.example.example"
+        // You can update the following values to match your application needs.
+        // For more information, see: https://docs.flutter.dev/deployment/android#reviewing-the-build-configuration.
+        minSdkVersion flutter.minSdkVersion
+        targetSdkVersion flutter.targetSdkVersion
+        versionCode flutterVersionCode.toInteger()
+        versionName flutterVersionName
+    }
+
+    buildTypes {
+        release {
+            // TODO: Add your own signing config for the release build.
+            // Signing with the debug keys for now, so `flutter run --release` works.
+            signingConfig signingConfigs.debug
+        }
+    }
+}
+
+flutter {
+    source '../..'
+}
+
+dependencies {
+    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
+}

example/android/app/src/debug/AndroidManifest.xml

@@ -0,0 +1,8 @@
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="com.example.example">
+    <!-- The INTERNET permission is required for development. Specifically,
+         the Flutter tool needs it to communicate with the running application
+         to allow setting breakpoints, to provide hot reload, etc.
+    -->
+    <uses-permission android:name="android.permission.INTERNET"/>
+</manifest>

example/android/app/src/main/AndroidManifest.xml

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+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="com.example.example">
+   <application
+        android:label="example"
+        android:name="${applicationName}"
+        android:icon="@mipmap/ic_launcher">
+        <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">
+            <!-- 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"
+              />
+            <intent-filter>
+                <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" />
+   </application>
+
+   <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
+   <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
+
+</manifest>

example/android/app/src/main/kotlin/com/example/example/MainActivity.kt

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+package com.example.example
+
+import io.flutter.embedding.android.FlutterActivity
+
+class MainActivity: FlutterActivity() {
+}

example/android/app/src/main/res/drawable-v21/launch_background.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<!-- Modify this file to customize your launch splash screen -->
+<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
+    <item android:drawable="?android:colorBackground" />
+
+    <!-- You can insert your own image assets here -->
+    <!-- <item>
+        <bitmap
+            android:gravity="center"
+            android:src="@mipmap/launch_image" />
+    </item> -->
+</layer-list>

example/android/app/src/main/res/drawable/launch_background.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<!-- Modify this file to customize your launch splash screen -->
+<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
+    <item android:drawable="@android:color/white" />
+
+    <!-- You can insert your own image assets here -->
+    <!-- <item>
+        <bitmap
+            android:gravity="center"
+            android:src="@mipmap/launch_image" />
+    </item> -->
+</layer-list>

example/android/app/src/main/res/values-night/styles.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <!-- Theme applied to the Android Window while the process is starting when the OS's Dark Mode setting is on -->
+    <style name="LaunchTheme" parent="@android:style/Theme.Black.NoTitleBar">
+        <!-- Show a splash screen on the activity. Automatically removed when
+             the Flutter engine draws its first frame -->
+        <item name="android:windowBackground">@drawable/launch_background</item>
+    </style>
+    <!-- Theme applied to the Android Window as soon as the process has started.
+         This theme determines the color of the Android Window while your
+         Flutter UI initializes, as well as behind your Flutter UI while its
+         running.
+
+         This Theme is only used starting with V2 of Flutter's Android embedding. -->
+    <style name="NormalTheme" parent="@android:style/Theme.Black.NoTitleBar">
+        <item name="android:windowBackground">?android:colorBackground</item>
+    </style>
+</resources>

example/android/app/src/main/res/values/styles.xml

@@ -0,0 +1,18 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <!-- Theme applied to the Android Window while the process is starting when the OS's Dark Mode setting is off -->
+    <style name="LaunchTheme" parent="@android:style/Theme.Light.NoTitleBar">
+        <!-- Show a splash screen on the activity. Automatically removed when
+             the Flutter engine draws its first frame -->
+        <item name="android:windowBackground">@drawable/launch_background</item>
+    </style>
+    <!-- Theme applied to the Android Window as soon as the process has started.
+         This theme determines the color of the Android Window while your
+         Flutter UI initializes, as well as behind your Flutter UI while its
+         running.
+
+         This Theme is only used starting with V2 of Flutter's Android embedding. -->
+    <style name="NormalTheme" parent="@android:style/Theme.Light.NoTitleBar">
+        <item name="android:windowBackground">?android:colorBackground</item>
+    </style>
+</resources>

example/android/app/src/profile/AndroidManifest.xml

@@ -0,0 +1,8 @@
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="com.example.example">
+    <!-- The INTERNET permission is required for development. Specifically,
+         the Flutter tool needs it to communicate with the running application
+         to allow setting breakpoints, to provide hot reload, etc.
+    -->
+    <uses-permission android:name="android.permission.INTERNET"/>
+</manifest>

example/android/build.gradle

@@ -0,0 +1,31 @@
+buildscript {
+    ext.kotlin_version = '1.6.10'
+    repositories {
+        google()
+        mavenCentral()
+    }
+
+    dependencies {
+        classpath 'com.android.tools.build:gradle:7.1.2'
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
+    }
+}
+
+allprojects {
+    repositories {
+        google()
+        mavenCentral()
+    }
+}
+
+rootProject.buildDir = '../build'
+subprojects {
+    project.buildDir = "${rootProject.buildDir}/${project.name}"
+}
+subprojects {
+    project.evaluationDependsOn(':app')
+}
+
+task clean(type: Delete) {
+    delete rootProject.buildDir
+}

example/android/gradle.properties

@@ -0,0 +1,3 @@
+org.gradle.jvmargs=-Xmx1536M
+android.useAndroidX=true
+android.enableJetifier=true

example/android/gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,6 @@
+#Fri Jun 23 08:50:38 CEST 2017
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.4-all.zip

example/android/settings.gradle

@@ -0,0 +1,11 @@
+include ':app'
+
+def localPropertiesFile = new File(rootProject.projectDir, "local.properties")
+def properties = new Properties()
+
+assert localPropertiesFile.exists()
+localPropertiesFile.withReader("UTF-8") { reader -> properties.load(reader) }
+
+def flutterSdkPath = properties.getProperty("flutter.sdk")
+assert flutterSdkPath != null, "flutter.sdk not set in local.properties"
+apply from: "$flutterSdkPath/packages/flutter_tools/gradle/app_plugin_loader.gradle"

example/lib/main.dart

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+import 'dart:io';
+import 'dart:typed_data';
+import 'package:flutter/material.dart';
+import 'package:file_picker/file_picker.dart';
+import 'package:moxplatform/moxplatform.dart';
+import 'package:moxplatform_platform_interface/moxplatform_platform_interface.dart';
+
+void main() {
+  runApp(const MyApp());
+}
+
+class MyApp extends StatelessWidget {
+  const MyApp({Key? key}) : super(key: key);
+
+  // This widget is the root of your application.
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      title: 'Flutter Demo',
+      theme: ThemeData(
+        // This is the theme of your application.
+        //
+        // Try running your application with "flutter run". You'll see the
+        // application has a blue toolbar. Then, without quitting the app, try
+        // changing the primarySwatch below to Colors.green and then invoke
+        // "hot reload" (press "r" in the console where you ran "flutter run",
+        // or simply save your changes to "hot reload" in a Flutter IDE).
+        // Notice that the counter didn't reset back to zero; the application
+        // is not restarted.
+        primarySwatch: Colors.blue,
+      ),
+      home: const MyHomePage(title: 'Flutter Demo Home Page'),
+    );
+  }
+}
+
+class MyHomePage extends StatefulWidget {
+  const MyHomePage({Key? key, required this.title}) : 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
+  // how it looks.
+
+  // This class is the configuration for the state. It holds the values (in this
+  // case the title) provided by the parent (in this case the App widget) and
+  // used by the build method of the State. Fields in a Widget subclass are
+  // always marked "final".
+
+  final String title;
+
+  @override
+  State<MyHomePage> createState() => _MyHomePageState();
+}
+
+class _MyHomePageState extends State<MyHomePage> {
+  int _counter = 0;
+
+  Future<void> _incrementCounter() async {
+    final result = await FilePicker.platform.pickFiles();
+    if (result == null) {
+      return;
+    }
+
+    final path = result.files.single.path;
+    await MoxplatformPlugin.crypto.encryptFile(
+      path!,
+      path + '.enc',
+      Uint8List.fromList(List.filled(32, 1)),
+      Uint8List.fromList(List.filled(16, 2)),
+      CipherAlgorithm.aes256CbcPkcs7,
+    );
+    print('DONE');
+    final lengthEnc = await File(path + ".enc").length();
+    final lengthOrig = await File(path).length();
+    print('Encrypted file is $lengthEnc Bytes large (Orig $lengthOrig)');
+
+    await MoxplatformPlugin.crypto.decryptFile(
+      path + '.enc',
+      path + '.dec',
+      Uint8List.fromList(List.filled(32, 1)),
+      Uint8List.fromList(List.filled(16, 2)),
+      CipherAlgorithm.aes256CbcPkcs7,
+    );
+    print('DONE');
+
+    final lengthDec = await File(path + ".dec").length();
+    print('Decrypted file is $lengthDec Bytes large (Orig $lengthOrig)');
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    // This method is rerun every time setState is called, for instance as done
+    // by the _incrementCounter method above.
+    //
+    // The Flutter framework has been optimized to make rerunning build methods
+    // fast, so that you can just rebuild anything that needs updating rather
+    // than having to individually change instances of widgets.
+    return Scaffold(
+      appBar: AppBar(
+        // Here we take the value from the MyHomePage object that was created by
+        // the App.build method, and use it to set our appbar title.
+        title: Text(widget.title),
+      ),
+      body: Center(
+        // Center is a layout widget. It takes a single child and positions it
+        // in the middle of the parent.
+        child: Column(
+          // Column is also a layout widget. It takes a list of children and
+          // arranges them vertically. By default, it sizes itself to fit its
+          // children horizontally, and tries to be as tall as its parent.
+          //
+          // Invoke "debug painting" (press "p" in the console, choose the
+          // "Toggle Debug Paint" action from the Flutter Inspector in Android
+          // Studio, or the "Toggle Debug Paint" command in Visual Studio Code)
+          // to see the wireframe for each widget.
+          //
+          // Column has various properties to control how it sizes itself and
+          // how it positions its children. Here we use mainAxisAlignment to
+          // center the children vertically; the main axis here is the vertical
+          // axis because Columns are vertical (the cross axis would be
+          // horizontal).
+          mainAxisAlignment: MainAxisAlignment.center,
+          children: <Widget>[
+            const Text(
+              'You have pushed the button this many times:',
+            ),
+            Text(
+              '$_counter',
+              style: Theme.of(context).textTheme.headline4,
+            ),
+          ],
+        ),
+      ),
+      floatingActionButton: FloatingActionButton(
+        onPressed: _incrementCounter,
+        tooltip: 'Increment',
+        child: const Icon(Icons.add),
+      ), // This trailing comma makes auto-formatting nicer for build methods.
+    );
+  }
+}

example/pubspec.yaml

@@ -0,0 +1,97 @@
+name: example
+description: A new Flutter project.
+
+# The following line prevents the package from being accidentally published to
+# pub.dev using `flutter pub publish`. This is preferred for private packages.
+publish_to: 'none' # Remove this line if you wish to publish to pub.dev
+
+# The following defines the version and build number for your application.
+# A version number is three numbers separated by dots, like 1.2.43
+# followed by an optional build number separated by a +.
+# Both the version and the builder number may be overridden in flutter
+# build by specifying --build-name and --build-number, respectively.
+# In Android, build-name is used as versionName while build-number used as versionCode.
+# Read more about Android versioning at https://developer.android.com/studio/publish/versioning
+# In iOS, build-name is used as CFBundleShortVersionString while build-number used as CFBundleVersion.
+# Read more about iOS versioning at
+# https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html
+version: 1.0.0+1
+
+environment:
+  sdk: ">=2.17.5 <3.0.0"
+
+# Dependencies specify other packages that your package needs in order to work.
+# To automatically upgrade your package dependencies to the latest versions
+# consider running `flutter pub upgrade --major-versions`. Alternatively,
+# dependencies can be manually updated by changing the version numbers below to
+# the latest version available on pub.dev. To see which dependencies have newer
+# versions available, run `flutter pub outdated`.
+dependencies:
+  flutter:
+    sdk: flutter
+
+  moxplatform:
+    hosted: https://git.polynom.me/api/packages/Moxxy/pub
+    version: 0.1.11+2
+  moxplatform_android:
+    hosted: https://git.polynom.me/api/packages/Moxxy/pub
+    version: 0.1.11+2
+
+  file_picker: 5.2.0+1
+    
+  # The following adds the Cupertino Icons font to your application.
+  # Use with the CupertinoIcons class for iOS style icons.
+  cupertino_icons: ^1.0.2
+
+dev_dependencies:
+  flutter_test:
+    sdk: flutter
+
+  # The "flutter_lints" package below contains a set of recommended lints to
+  # encourage good coding practices. The lint set provided by the package is
+  # activated in the `analysis_options.yaml` file located at the root of your
+  # package. See that file for information about deactivating specific lint
+  # rules and activating additional ones.
+  flutter_lints: ^2.0.0
+
+# For information on the generic Dart part of this file, see the
+# following page: https://dart.dev/tools/pub/pubspec
+
+# The following section is specific to Flutter packages.
+flutter:
+
+  # The following line ensures that the Material Icons font is
+  # included with your application, so that you can use the icons in
+  # the material Icons class.
+  uses-material-design: true
+
+  # To add assets to your application, add an assets section, like this:
+  # assets:
+  #   - images/a_dot_burr.jpeg
+  #   - images/a_dot_ham.jpeg
+
+  # An image asset can refer to one or more resolution-specific "variants", see
+  # https://flutter.dev/assets-and-images/#resolution-aware
+
+  # For details regarding adding assets from package dependencies, see
+  # https://flutter.dev/assets-and-images/#from-packages
+
+  # To add custom fonts to your application, add a fonts section here,
+  # in this "flutter" section. Each entry in this list should have a
+  # "family" key with the font family name, and a "fonts" key with a
+  # list giving the asset and other descriptors for the font. For
+  # example:
+  # fonts:
+  #   - family: Schyler
+  #     fonts:
+  #       - asset: fonts/Schyler-Regular.ttf
+  #       - asset: fonts/Schyler-Italic.ttf
+  #         style: italic
+  #   - family: Trajan Pro
+  #     fonts:
+  #       - asset: fonts/TrajanPro.ttf
+  #       - asset: fonts/TrajanPro_Bold.ttf
+  #         weight: 700
+  #
+  # For details regarding fonts from package dependencies,
+  # see https://flutter.dev/custom-fonts/#from-packages

example/pubspec_overrides.yaml

@@ -0,0 +1,8 @@
+# melos_managed_dependency_overrides: moxplatform,moxplatform_android,moxplatform_platform_interface
+dependency_overrides:
+  moxplatform:
+    path: ../packages/moxplatform
+  moxplatform_android:
+    path: ../packages/moxplatform_android
+  moxplatform_platform_interface:
+    path: ../packages/moxplatform_platform_interface

example/test/widget_test.dart

@@ -0,0 +1,30 @@
+// This is a basic Flutter widget test.
+//
+// To perform an interaction with a widget in your test, use the WidgetTester
+// utility in the flutter_test package. For example, you can send tap and scroll
+// gestures. You can also use WidgetTester to find child widgets in the widget
+// tree, read text, and verify that the values of widget properties are correct.
+
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+import 'package:example/main.dart';
+
+void main() {
+  testWidgets('Counter increments smoke test', (WidgetTester tester) async {
+    // Build our app and trigger a frame.
+    await tester.pumpWidget(const MyApp());
+
+    // Verify that our counter starts at 0.
+    expect(find.text('0'), findsOneWidget);
+    expect(find.text('1'), findsNothing);
+
+    // Tap the '+' icon and trigger a frame.
+    await tester.tap(find.byIcon(Icons.add));
+    await tester.pump();
+
+    // Verify that our counter has incremented.
+    expect(find.text('0'), findsNothing);
+    expect(find.text('1'), findsOneWidget);
+  });
+}

packages/moxplatform/lib/src/plugin.dart

@@ -3,4 +3,5 @@ import 'package:moxplatform_platform_interface/moxplatform_platform_interface.da
 class MoxplatformPlugin {
   static IsolateHandler get handler => MoxplatformInterface.handler;
   static MediaScannerImplementation get media => MoxplatformInterface.media;
+  static CryptographyImplementation get crypto => MoxplatformInterface.crypto;
 }

packages/moxplatform_android/android/src/main/java/me/polynom/moxplatform_android/MoxplatformAndroidPlugin.java

@@ -6,15 +6,23 @@ import android.content.Context;
 import android.content.Intent;
 import android.content.IntentFilter;
 import android.content.SharedPreferences;
+import android.os.Message;
 import android.util.Log;
 
 import androidx.annotation.NonNull;
 import androidx.core.content.ContextCompat;
 import androidx.localbroadcastmanager.content.LocalBroadcastManager;
 
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
 import java.util.ArrayList;
 import java.util.List;
 
+import javax.crypto.Cipher;
+import javax.crypto.CipherOutputStream;
+import javax.crypto.spec.IvParameterSpec;
+import javax.crypto.spec.SecretKeySpec;
+
 import io.flutter.embedding.engine.plugins.FlutterPlugin;
 import io.flutter.embedding.engine.plugins.service.ServiceAware;
 import io.flutter.embedding.engine.plugins.service.ServicePluginBinding;
@@ -136,6 +144,38 @@ public class MoxplatformAndroidPlugin extends BroadcastReceiver implements Flutt
         }
         result.success(true);
         break;
+      case "encryptFile":
+        Thread encryptionThread = new Thread(new Runnable() {
+          @Override
+          public void run() {
+            ArrayList args = (ArrayList) call.arguments;
+            String src = (String) args.get(0);
+            String dest = (String) args.get(1);
+            byte[] key = (byte[]) args.get(2);
+            byte[] iv = (byte[]) args.get(3);
+            int algorithm = (int) args.get(4);
+
+            result.success(encryptFile(src, dest, key, iv, algorithm));
+          }
+        });
+        encryptionThread.start();
+        break;
+      case "decryptFile":
+        Thread decryptionThread = new Thread(new Runnable() {
+          @Override
+          public void run() {
+            ArrayList args = (ArrayList) call.arguments;
+            String src = (String) args.get(0);
+            String dest = (String) args.get(1);
+            byte[] key = (byte[]) args.get(2);
+            byte[] iv = (byte[]) args.get(3);
+            int algorithm = (int) args.get(4);
+
+            result.success(decryptFile(src, dest, key, iv, algorithm));
+          }
+        });
+        decryptionThread.start();
+        break;
       default:
         result.notImplemented();
         break;
@@ -175,4 +215,84 @@ public class MoxplatformAndroidPlugin extends BroadcastReceiver implements Flutt
     Log.d(TAG, "Detached from service");
     this.service = null;
   }
+
+  private String getCipherSpecFromInteger(int algorithm) {
+    switch (algorithm) {
+      case 0: return "AES_128/GCM/NoPadding";
+      case 1: return "AES_256/GCM/NoPadding";
+      case 2: return "AES_256/CBC/PKCS7PADDING";
+      default:
+        Log.d(TAG, "INVALID ALGORITHM");
+        return "";
+    }
+  }
+
+  public boolean encryptFile(String src, String dest, byte[] key, byte[] iv, int algorithm) {
+    String spec = getCipherSpecFromInteger(algorithm);
+    if (spec.isEmpty()) {
+      return false;
+    }
+
+    // Shamelessly stolen from https://github.com/hugo-pcl/native-crypto-flutter/pull/3
+    byte[] buffer = new byte[8096];
+    SecretKeySpec sk = new SecretKeySpec(key, spec);
+    try {
+      Cipher cipher = Cipher.getInstance(spec);
+      cipher.init(Cipher.ENCRYPT_MODE, sk, new IvParameterSpec(iv));
+      FileInputStream fin = new FileInputStream(src);
+      FileOutputStream fout = new FileOutputStream(dest);
+      CipherOutputStream cout = new CipherOutputStream(fout, cipher);
+      int len = 0;
+      while (true) {
+        len = fin.read(buffer);
+        if (len != 0 && len > 0) {
+          cout.write(buffer, 0, len);
+        } else {
+          break;
+        }
+      }
+      cout.flush();
+      cout.close();
+      fin.close();
+      return true;
+    } catch (Exception ex) {
+      Log.d(TAG, "ENC: " + ex.getMessage());
+      return false;
+    }
+  }
+
+  public boolean decryptFile(String src, String dest, byte[] key, byte[] iv, int algorithm) {
+    String spec = getCipherSpecFromInteger(algorithm);
+    if (spec.isEmpty()) {
+      return false;
+    }
+
+    // Shamelessly stolen from https://github.com/hugo-pcl/native-crypto-flutter/pull/3
+    byte[] buffer = new byte[8096];
+    SecretKeySpec sk = new SecretKeySpec(key, spec);
+    try {
+      Cipher cipher = Cipher.getInstance(spec);
+      cipher.init(Cipher.DECRYPT_MODE, sk, new IvParameterSpec(iv));
+      FileInputStream fin = new FileInputStream(src);
+      FileOutputStream fout = new FileOutputStream(dest);
+      CipherOutputStream cout = new CipherOutputStream(fout, cipher);
+      Log.d(TAG, "Reading from " + src + ", writing to " + dest);
+      int len = 0;
+      while (true) {
+        len = fin.read(buffer);
+        if (len != 0 && len > 0) {
+          cout.write(buffer, 0, len);
+        } else {
+          break;
+        }
+      }
+      cout.flush();
+      cout.close();
+      fin.close();
+      return true;
+    } catch (Exception ex) {
+      Log.d(TAG, "DEC: " + ex.getMessage());
+      return false;
+    }
+  }
 }

packages/moxplatform_android/lib/src/crypto_android.dart

@@ -0,0 +1,31 @@
+import 'dart:typed_data';
+import 'package:flutter/services.dart';
+import 'package:moxplatform_platform_interface/moxplatform_platform_interface.dart';
+
+class AndroidCryptographyImplementation extends CryptographyImplementation {
+  final _methodChannel = const MethodChannel('me.polynom.moxplatform_android');
+
+  @override
+  Future<bool> encryptFile(String sourcePath, String destPath, Uint8List key, Uint8List iv, CipherAlgorithm algorithm) async {
+    final result = await _methodChannel.invokeMethod<bool>('encryptFile', [
+      sourcePath,
+      destPath,
+      key,
+      iv,
+      algorithm.toInt(),
+    ]);
+    return result ?? false;
+  }
+
+  @override
+  Future<bool> decryptFile(String sourcePath, String destPath, Uint8List key, Uint8List iv, CipherAlgorithm algorithm) async {
+    final result = await _methodChannel.invokeMethod<bool>('decryptFile', [
+      sourcePath,
+      destPath,
+      key,
+      iv,
+      algorithm.toInt(),
+    ]);
+    return result ?? false;
+  }
+}

packages/moxplatform_android/lib/src/plugin_android.dart

@@ -1,3 +1,4 @@
+import 'package:moxplatform_android/src/crypto_android.dart';
 import 'package:moxplatform_android/src/isolate_android.dart';
 import 'package:moxplatform_android/src/media_android.dart';
 import 'package:moxplatform_platform_interface/moxplatform_platform_interface.dart';
@@ -8,6 +9,7 @@ class MoxplatformAndroidPlugin extends MoxplatformInterface {
     print('MoxplatformAndroidPlugin: Registering implementation');
     MoxplatformInterface.handler = AndroidIsolateHandler();
     MoxplatformInterface.media = AndroidMediaScannerImplementation();
+    MoxplatformInterface.crypto = AndroidCryptographyImplementation();
   }
 
   @override

packages/moxplatform_platform_interface/lib/moxplatform_platform_interface.dart

@@ -1,5 +1,7 @@
 library moxplatform_platform_interface;
 
+export 'src/crypto.dart';
+export 'src/crypto_stub.dart';
 export 'src/interface.dart';
 export 'src/isolate.dart';
 export 'src/isolate_stub.dart';

packages/moxplatform_platform_interface/lib/src/crypto.dart

@@ -0,0 +1,32 @@
+import 'dart:typed_data';
+
+enum CipherAlgorithm {
+  aes128GcmNoPadding,
+  aes256GcmNoPadding,
+  aes256CbcPkcs7,
+}
+
+extension CipherAlgorithmToIntExtension on CipherAlgorithm {
+  int toInt() {
+    switch (this) {
+      case CipherAlgorithm.aes128GcmNoPadding: return 0;
+      case CipherAlgorithm.aes256GcmNoPadding: return 1;
+      case CipherAlgorithm.aes256CbcPkcs7: return 2;
+    }
+  }
+}
+
+/// Wrapper around platform-native cryptography APIs
+abstract class CryptographyImplementation {
+  /// Encrypt the file at [sourcePath] using [algorithm] and write the result back to
+  /// [destPath]. Note that this function runs off-thread as to not block the UI thread.
+  ///
+  /// Resolves to true if the encryption was successful. Resolves to fale on failure.
+  Future<bool> encryptFile(String sourcePath, String destPath, Uint8List key, Uint8List iv, CipherAlgorithm algorithm);
+
+  /// Decrypt the file at [sourcePath] using [algorithm] and write the result back to
+  /// [destPath]. Note that this function runs off-thread as to not block the UI thread.
+  /// 
+  /// Resolves to true if the encryption was successful. Resolves to fale on failure.
+  Future<bool> decryptFile(String sourcePath, String destPath, Uint8List key, Uint8List iv, CipherAlgorithm algorithm);
+}

packages/moxplatform_platform_interface/lib/src/crypto_stub.dart

@@ -0,0 +1,14 @@
+import 'dart:typed_data';
+import 'package:moxplatform_platform_interface/src/crypto.dart';
+
+class StubCryptographyImplementation extends CryptographyImplementation {
+  @override
+  Future<bool> encryptFile(String sourcePath, String destPath, Uint8List key, Uint8List iv, CipherAlgorithm algorithm) async {
+    return false;
+  }
+
+  @override
+  Future<bool> decryptFile(String sourcePath, String destPath, Uint8List key, Uint8List iv, CipherAlgorithm algorithm) async {
+    return false;
+  }
+}

packages/moxplatform_platform_interface/lib/src/interface.dart

@@ -1,3 +1,5 @@
+import 'package:moxplatform_platform_interface/src/crypto.dart';
+import 'package:moxplatform_platform_interface/src/crypto_stub.dart';
 import 'package:moxplatform_platform_interface/src/isolate.dart';
 import 'package:moxplatform_platform_interface/src/isolate_stub.dart';
 import 'package:moxplatform_platform_interface/src/media.dart';
@@ -11,6 +13,7 @@ abstract class MoxplatformInterface extends PlatformInterface {
   
   static IsolateHandler handler = StubIsolateHandler();
   static MediaScannerImplementation media = StubMediaScannerImplementation();
+  static CryptographyImplementation crypto = StubCryptographyImplementation();
 
   /// Return the current platform name.
   Future<String?> getPlatformName();