ark-circom

Arkworks bindings to Circom's R1CS, for Groth16 Proof and Witness generation in Rust.

Documentation

Clone the repository and run cd ark-circom/ && cargo doc --open

Add ark-circom to your repository

[dependencies]

ark-circom = { git = "https://github.com/gakonst/ark-circom.git" }

Example

// Load the WASM and R1CS for witness and proof generation
let cfg = CircomConfig::<Bn254>::new(
    "./test-vectors/mycircuit.wasm",
    "./test-vectors/mycircuit.r1cs",
)?;

// Insert our public inputs as key value pairs
let mut builder = CircomBuilder::new(cfg);
builder.push_input("a", ark_circom::circom::Inputs::BigInt(3.into()));
builder.push_input("b", ark_circom::circom::Inputs::BigInt(11.into()));
// for 2d array, use
// builder.push_input("a", ark_circom::circom::Inputs::BigIntVec(vec[3.into()]));
// for 3d array, use
// builder.push_input(
//     "a",
//     ark_circom::circom::InputValue::BigIntVecVec(vec![
//         vec![
//             3.into(),
//         ],
//         vec![
//             11.into(),
//         ],
//     ]),
// );

// Create an empty instance for setting it up
let circom = builder.setup();

// Run a trusted setup
let mut rng = thread_rng();
let params = generate_random_parameters_with_reduction(circom, &mut rng)?;

// Get the populated instance of the circuit with the witness
let circom = builder.build()?;

let inputs = circom.get_public_inputs().unwrap();

// Generate the proof
let proof = prove(&params, circom, &mut rng)?;

// Check that the proof is valid
let pvk = process_vk(&params.vk)?;
let verified = verify_with_processed_vk(&pvk, &inputs, &proof)?;
assert!(verified);

Running the tests

Tests require the following installed:

1. solc. We also recommend using solc-select for more flexibility.
2. ganache-cli

Features

• Witness generation using Circom's WASM witness code
• ZKey parsing into Arkworks Proving Key over BN254
• Compatibility layer for Ethereum types, so that proofs can be used in Solidity verifiers
• Proof generations and verification using Arkworks
• CLI for common operations

Acknowledgements

This library would not have been possibly without the great work done in:

• zkutil
• snarkjs

Special shoutout to Kobi Gurkan for all the help in parsing SnarkJS' ZKey file format.