Noir Adapter

Mopro supports the integration of Noir circuits, enabling zero-knowledge proofs in native mobile applications with ease. This adapter builds upon foundational work from the zkPassport team and streamlines cross-platform integration with performance, reliability, and developer experience in mind.

Samples

You can explore real examples of how the Noir adapter works in these projects:

• mopro-zkemail-nr
• stealthnote-mobile
• mopro-wallet-connect-noir

Setting Up the Rust Project

To get started, follow the Rust Setup Guide and activate the noir feature in your Cargo.toml:

[features]
default = ["mopro-ffi/noir"]

[dependencies]
mopro-ffi = { version = "0.2" }
# ...

info

The Noir adapter depends on zkmopro/noir-rs. Please checkout the usage and the version here.

Current version: Supports Noir 1.0.0-beta.8-3 with bb 1.0.0-nightly.20250723 with updated dependencies and enhanced functionality.

Backend: The adapter uses the Barretenberg backend, which is automatically downloaded from the released GitHub artifacts at zkmopro/aztec-packages.

Hash Function Selection

The Noir adapter supports two functions as oracle hash options for different use cases:

• Poseidon hash: Default choice, optimized for performance and off-chain verification
• Keccak256 hash: Gas-efficient, required for Solidity verifier compatibility and on-chain verification

The hash function is automatically selected based on the on_chain parameter.

Key Features

• Automatic Hash Selection: Automatically chooses between Poseidon (performance) and Keccak256 (EVM compatibility) based on your use case
• Memory Optimization: Low memory mode available for mobile devices
• Cross-Platform: Works across iOS, Android, and other supported platforms

Proving and Verifying Functions

Preparing SRS

Please follow this guide to generate the SRS for your Noir circuit: Downloading SRS (Structured Reference String)

Rust API

The Noir adapter provides three main functions that automatically handle hash function selection based on the on_chain parameter:

pub fn generate_noir_proof(
    circuit_path: String,
    srs_path: Option<String>,
    inputs: Vec<String>,
    on_chain: bool,
    vk: Vec<u8>,
    low_memory_mode: bool,
) -> Result<Vec<u8>, MoproError>;

pub fn verify_noir_proof(
    circuit_path: String,
    proof: Vec<u8>,
    on_chain: bool,
    vk: Vec<u8>,
    low_memory_mode: bool,
) -> Result<bool, MoproError>;

pub fn get_noir_verification_key(
    circuit_path: String,
    srs_path: Option<String>,
    on_chain: bool,
    low_memory_mode: bool,
) -> Result<Vec<u8>, MoproError>;

Parameters

• circuit_path: Path to the compiled Noir .json circuit
• srs_path: Optional path to the structured reference string
• inputs: List of strings representing public/private inputs (proof generation only)
• proof: The serialized proof to verify (verification only)
• on_chain: If true, uses Keccak256 hash for Solidity compatibility; if false, uses Poseidon hash for better performance
• vk: Pre-generated verification key bytes
• low_memory_mode: Enables memory optimization for resource-constrained environments

Usage Notes

• Hash Selection: Set on_chain = true for Ethereum/EVM compatibility, or on_chain = false for better performance
• Verification Keys: Pre-generate verification keys using get_noir_verification_key and reuse them for better performance
• Memory Optimization: Enable low_memory_mode = true for resource-constrained mobile environments

Platform Support

The Noir adapter supports the following target platforms with Barretenberg backend binaries:

Platform	Target Triple	Status
macOS (Intel)	x86_64-apple-darwin	✅
macOS (M Series)	aarch64-apple-darwin	✅
iOS Device	aarch64-apple-ios	✅
iOS aarch64 Simulator	aarch64-apple-ios-sim	✅
iOS x86_64 Simulator	x86_64-apple-ios	✅
Android aarch64 Device	aarch64-linux-android	✅
Android x86_64 Emulator	x86_64-linux-android	✅
Linux Desktop	x86_64-unknown-linux-gnu	✅

All platforms use pre-compiled Barretenberg binaries automatically downloaded from zkmopro/aztec-packages releases during the build process.