Flutter SDK

In this section, you'll learn how to build a Flutter SDK using Mopro's native bindings. The process includes the following steps:

1. Generate the binding using the Mopro CLI
2. Integrate the binding into a Flutter Package
3. How to install the Flutter SDK
4. How to use the package
5. How to run an example app

Generate the bindings using the Mopro CLI

To get started with building Mopro bindings, refer to the Getting Started section. If you’d like to generate custom bindings for your own circuits or proving schemes, see the guide: Rust Setup for Android/iOS Bindings.

Choose Flutter to build the bindings, or run

mopro build --platforms flutter

to generate the flutter package.

Then you will have a mopro_flutter_bindings in the project directory.

Integrate the bindings into a Flutter Package

1. Clone the SDK template repository:

git clone https://github.com/zkmopro/mopro_flutter_package

2. Replace the generated bindings:

replace the entire bindings directory mopro_flutter_package with your generated files in the current folder:

├── android
├── cargokit
├── flutter_rust_bridge.yaml
├── ios
├── lib
├── pubspec.yaml
└── rust

or running e.g.

cp -R \
  mopro_flutter_bindings/android \
  mopro_flutter_bindings/cargokit \
  mopro_flutter_bindings/flutter_rust_bridge.yaml \
  mopro_flutter_bindings/ios \
  mopro_flutter_bindings/lib \
  mopro_flutter_bindings/pubspec.yaml \
  mopro_flutter_bindings/rust \
  mopro_flutter_package/

How to install the Flutter SDK

Add mopro_flutter_bindings to your project by manually editing pubspec.yaml.

dependencies:
    flutter:
        sdk: flutter

    mopro_flutter_bindings: # Or change to your own package name
        git:
            url: https://github.com/zkmopro/mopro_flutter_package # Or change to your own URL

info

If you need to update your keys, include your compiled Circom .zkey file as an asset. Add the asset path to your pubspec.yaml under the flutter: section:

flutter:
    uses-material-design: true # Ensure this is present
    assets:
        # Add the directory containing your .zkey file(s)
        - assets/circuits/
        # Or specify the file directly:
        # - assets/circuits/multiplier2_final.zkey

Make sure the path points correctly to where you've placed your .zkey file within your Flutter project.

Run the following command in your terminal from the root of your Flutter project:

flutter pub get

How to use the package

Here is an example of how to integrate and use this package

Update the main function to initialize the Rust library before running the app:

void main() async {
  await RustLib.init();
  runApp(const MyApp());
}

Import the package and use it:

// Import the package
import 'package:mopro_flutter_bindings/src/rust/third_party/mopro_example_app.dart'; // Change to your library name
import 'package:mopro_flutter_bindings/src/rust/frb_generated.dart';

final zkeyPath = await copyAssetToFileSystem(
    'assets/multiplier2_final.zkey',
)

// Corresponds to the inputs of multiplier2.circom
const int a = 3;
const int b = 5;
final Map<String, List<String>> inputs = {
    'a': [a.toString()],
    'b': [b.toString()],
};
// Convert inputs to JSON string
final String inputsJson = jsonEncode(inputs);

// Use the zkey asset path provided in pubspec.yaml
final CircomProofResult proofResult = await generateCircomProof(
    zkeyPath: zkeyPath,
    circuitInputs: inputsJson,
    proofLib: ProofLib.arkworks,
);

final bool isValid = await verifyCircomProof(
    zkeyPath: zkeyPath,
    proofResult: proofResult,
    proofLib: ProofLib.arkworks,
);

print('Generated Proof: ${proofResult.proof}');
print('Public Inputs/Outputs: ${proofResult.inputs}');
print('Verification result: $isValid');

How to run an example app

• Open the example app that uses the defined flutter package in the example/ folder

  cd example
• Install the dependencies

  flutter pub get
• Open an iOS simulator/device or an Android emulator/device and run the example app

  flutter run
• Clean the cache if you update the bindings and it throws errors

  flutter clean