mopro

Making client-side proving on mobile simple (and fast).

Overview

• mopro-cli - core Rust CLI util (NOTE: Very early; use mopro-core for now).
• mopro-core - core mobile Rust library.
• mopro-ffi - wraps mopro-core and exposes UniFFI bindings.
• mopro-ios - iOS CocoaPod library exposing native Swift bindings.
• mopro-android - Android library exposing native Kotlin bindings.
• mopro-example-app - example iOS app using mopro-ios.
• ark-zkey - helper utility to make zkey more usable and faster in arkworks.

Architecture

The following illustration shows how mopro and its components fit together into the wider ZKP ecosystem:

Zooming in a bit:

How to use

Prepare circuits

• Install circom and snarkjs
• Run ./scripts/prepare.sh to check all prerequisites are set.

(Note that we require uniffi-bindgen to be 0.25, if you have an older version you might need to remove this to re-install the latest).

Configure settings

By creating a toml configuration file you can specify what build settings you want to use. Example is provided in config-example.toml:

# config-example.toml

[build]
# For iOS device_type can be x86_64, simulator, device
# For Android device_type can be x86_64, arm, arm64
device_type = "simulator" # Options: x86_64, simulator, device, arm, arm64

# debug is for Rust library to be in debug mode and release for release mode
# We recommend release mode by default for performance
build_mode = "release"    # Options: debug, release

[circuit]
dir = "examples/circom/keccak256" # Directory of the circuit
name = "keccak256_256_test"       # Name of the circuit

[dylib]
use_dylib = false         # Options: true, false
name = "keccak256.dylib" # Name of the dylib file, only used if use_dylib is true

iOS

Prepare

• Install cocoapods

Build Bindings

To build bindings for iOS, adjust settings in your config file (we recommend starting with simulator and release) and run:

./scripts/build_ios.sh config-example.toml

Open the mopro-ios/MoproKit/Example/MoproKit.xcworkspace in Xcode.

Update Bindings

To update bindings, run ./scripts/update_bindings.sh config-example.

Android

Prepare

• Install Android Studio
• Open Android Studio, and navigate to SDK Manager > SDK Tools > NDK (Side by Side) as laid out on the Android Developer site.
• Export $ANDROID_HOME and change {USER_NAME} to your username

  export ANDROID_HOME="/Users/{USER_NAME}/Library/Android/sdk"

• Locate which NDK version you have by

  ls $ANDROID_HOME/ndk
  # 26.1.10909125

  and set it to your NDK_PATH environment variable. e.g.

  NDK_PATH=$ANDROID_HOME/ndk/26.1.10909125

  Reference: Running Rust on Android with UniFFI

Build and Update Bindings

To build bindings for android simulator debug mode, run

./scripts/build_android.sh config-example.toml

• Device types: x86_64, x86, arm, arm64 Check your device architecture here: https://doc.e.foundation/devices For Android Studio simulator (Pixel series), choose arm64
• Mode: debug, release

Community and Talks

Join the Telegram group here.

Talk by @oskarth at ProgCrypto/Devconnect (Istanbul, November 2023): Slides (video pending)

Performance

Preliminary benchmarks on an iPhone 14 Max Pro:

• Keccak256 (150k constraints): 1.5s
  • ~x10-20 faster vs comparable circuit in browser
• anon-aadhaar / RSA Verify: ~6.5s
  • ~5s for witness generation (still in WASM), ~2s prover time
  • 80% of time on witness generation
  • ~x10 faster vs browser on phone
• Bottlenecks: loading zkey and wasm witness generation

Acknowledgements

This work is sponsored by a joint grant from PSE and 0xPARC.