Deimos
Deimos

Noir Circuit Integration Guide for MoPro

This guide explains how to integrate Noir circuits into the app for mobile zero-knowledge proof benchmarking.

Prerequisites

  • A Noir circuit compiled for noirc v1.0.0-beta.8 (see Compiler compatibility below)
  • MoPro CLI installed (cargo install --path mopro/cli)
  • Android Studio (for Android development) or a USB cable to test with an actual mobile
  • The circuit artifacts: the compiled circuit JSON (.json) and the SRS/proving parameters (.srs). Optionally a verification key file (.vk) if you plan to use local VK instead of fetching it from the network.

Integration Overview

MoPro enables mobile zero-knowledge proof generation through:

  • Rust Core: Circuit integration and FFI exports
  • UniFFI Bindings: Type-safe mobile bindings generation
  • Mobile Apps: Flutter/Android/iOS applications with benchmarking UI
  • Asset Management: Circuit files (.json, .srs, and optional .vk) bundled with apps

Step-by-Step Integration

Noir integration in MoPro is lightweight: copy the compiled circuit artifacts to the Flutter assets, add them to pubspec.yaml, and use the existing Noir flow in the UI (flutter/lib/main.dart) which already has helper functions to load assets and call the MoPro plugin.

Step 1: Build Your Noir Circuit for Compatibility

Ensure your Noir circuit is compiled with the required compiler version and target:

  • Required noirc version: v1.0.0-beta.8

If you have rustup and cargo installed, install or pin the noirc toolchain as documented in the Noir docs. Verify your installation:

bash
noirc --version  # verify installed version is v1.0.0-beta.8

Build the circuit to get the .json and .srs (and optionally .vk) files. Typical outputs are:

  • my_circuit.json - the compiled circuit description used by the mobile prover
  • my_circuit.srs - structured reference string / proving parameters
  • my_circuit.vk - optional verification key blob for local verification

Step 2: Copy Artifacts into Flutter Assets

From your Noir build output folder, copy the .json and .srs files into the MoPro Flutter assets directory. Optionally copy a .vk if you plan to use a local verification key.

bash
# From the repository root
cp path/to/my_circuit.json benchmarking-suite/moPro/mopro-example-app/flutter/assets/my_circuit.json
cp path/to/my_circuit.srs benchmarking-suite/moPro/mopro-example-app/flutter/assets/my_circuit.srs

# Optional local verification key
cp path/to/my_circuit.vk benchmarking-suite/moPro/mopro-example-app/flutter/assets/my_circuit.vk

If you want the asset to use a standardized name (so the UI mapping picks it up), prefer names like sha256.json,sha256.srs, keccak256.json, etc. — matching the algorithm labels used in the app.

Step 3: Update pubspec.yaml

Add your assets to the Flutter pubspec.yaml so they are bundled into the app:

flutter:
  assets:
    - assets/sha256.json
    - assets/sha256.srs
    - assets/sha256.vk # optional

    # other Noir circuits
    - assets/keccak256.json
    - assets/keccak256.srs

Run flutter pub get to ensure assets are recognized.

Step 4: UI Integration (No Code Compile Required in Most Cases)

The mopro-example-app Flutter code already contains Noir-specific helper logic in flutter/lib/main.dart. Key points to verify or adapt in the UI:

  • _getNoirSettings() selects the correct asset file names and attempts to load a .vk (verification key) from bundled assets; if missing, it falls back to asking the MoPro plugin to provide it at runtime.
  • _textToNoirInput() converts string input into a 32-byte padded byte array (as a list of decimal strings) expected by Noir circuits.
  • _generateNoirProof() and _verifyNoirProof() call the plugin methods generateNoirProof and verifyNoirProof with the parameters returned by _getNoirSettings().

You usually don't need to change the UI beyond adding your algorithm name to the algorithm selection mapping in_getAlgorithmsForFramework() if you want it to appear in the selection UI.

case 'noir':
  return ['SHA256', 'Keccak256', 'Poseidon', 'MiMC', 'Pedersen'];

If you add new algorithm names, update _getNoirSettings() with a case that returns the(assetPath, srsPath, onChain, verificationKey) tuple for that algorithm.

Step 5: Build & Run the App

From the mopro-example-app directory:

bash
cd benchmarking-suite/moPro/mopro-example-app/flutter
flutter pub get
flutter run

On first runs, the app will attempt to load .vk files from assets. If they aren't present, the app will call the MoPro plugin to fetch the verification key (this behavior is implemented in _getNoirSettings() in main.dart).

Troubleshooting Common Issues

Issue: App Can't Find Assets at Runtime

Solution:

  • Verify pubspec.yaml contains the asset entries and flutter pub get ran successfully.
  • Confirm the asset file names match those referenced in _getNoirSettings().

Issue: Proof Generation Fails

Solution:

  • Check input format — Noir circuits will expect fields in the format you compiled the circuit for. The default helper in main.dart pads to 32 bytes.
  • Check the Noir compiler version — mismatch between the circuit's expected runtime and the mobile plugin can cause errors. Recompile the circuit with noirc v1.0.0-beta.8.

Noir Compiler Compatibility (v1.0.0-beta.8)

To ensure circuits compile correctly for the MoPro mobile runtime, compile using noirc v1.0.0-beta.8:

  • Verify your local noirc matches the version: noirc --version (should report v1.0.0-beta.8)
  • Recompile your circuits with the exact toolchain and export the .json and .srs artifacts.
  • If you encounter ABI or format errors, re-check the Noir release notes between your installed version and the required version for changes to output formats.

Quick QA Checklist

  • .json and .srs are copied into benchmarking-suite/moPro/mopro-example-app/flutter/assets
  • pubspec.yaml includes the new assets and flutter pub get completes
  • UI algorithm list includes the new Noir circuit name (if you want it selectable)
  • _getNoirSettings() returns the right paths for the algorithm
  • Running the app can generate and verify a proof for the circuit on device/emulator

References