Circom Prover

Circom prover is a Rust library for generating and verifying proofs for Circom circuits. It is designed to be used in cross-platform applications, and is compatible with the Mopro library.

Usage

Install circom-prover

cargo add circom-prover

Depends on the witness generation method, build the rust witness function first. Here is how to use the rust-witness generator.

Include the crate in your Cargo.toml:

[dependencies]
rust-witness = "0.1"
num-bigint = "0.4"

[build-dependencies]
rust-witness = "0.1"

In build.rs, add the following code to compile the witness generator wasm sources (.wasm) into a native library and link to it:

rust_witness::transpile::transpile_wasm("../path to directory containing your wasm sources");
// e.g. rust_witness::transpile::transpile_wasm("./test-vectors".to_string());
// The directory should contain the following files:
// - <circuit name>.wasm

Proof Generation

use std::collections::HashMap;
use circom_prover::{prover::ProofLib, witness::WitnessFn, CircomProver};

// Prepare witness generator
rust_witness::witness!(multiplier2);

// Prepare inputs
let inputs = HashMap::from([
    ("a".to_string(), vec!["1".to_string()]),
    ("b".to_string(), vec!["2".to_string()]),
]);
let input_str = serde_json::to_string(&inputs).unwrap();

// Prepare zkey path
let zkey_path = "./test-vectors/multiplier2_final.zkey".to_string();

// Generate proof
let result = CircomProver::prove(
    ProofLib::Arkworks,
    WitnessFn::RustWitness(multiplier2_witness),
    input_str,
    zkey_path.clone(),
).unwrap();

Proof Verification

// Verify proof
let valid = CircomProver::verify(
    ProofLib::Arkworks,
    result,
    zkey_path,
).unwrap();

Advanced usage

circom-prover also supports witnesscalc and rapidsnark for advanced users. These tools offer better performance but may not be entirely stable.

Below is a tutorial on how to enable witnesscalc and rapidsnark.

Set feature flags

[dependencies]
circom-prover = { version = "0.1", default-features = false, features = ["witnesscalc", "rapidsnark"] }
witnesscalc-adapter = "0.1"
anyhow = "1.0"

[build-dependencies]
witnesscalc-adapter = "0.1"
circom-prover = { version = "0.1", default-features = false, features = ["rapidsnark"] }

witnesscalc

Install dependencies:

• Linux:

sudo apt install build-essential cmake m4 nasm libstdc++6

• MacOS

brew install nasm

Rust toolchain: cargo 1.81.0 (2dbb1af80 2024-08-20)

In build.rs, add the following code to compile the witness generator wasm sources (.wasm) into a native library and link to it:

witnesscalc_adapter::build_and_link("../path to directory containing your C++ sources");
// e.g. witnesscalc_adapter::build_and_link("../testdata");
// The directory should contain the following files:
// - <circuit name>.cpp
// - <circuit name>.dat

Proof Generation

use circom_prover::{prover::ProofLib, witness::WitnessFn, CircomProver};
use std::collections::HashMap;
use anyhow::Result;

// Prepare witness generator
witnesscalc_adapter::witness!(multiplier2);

// Prepare inputs
let inputs = HashMap::from([
    ("a".to_string(), vec!["1".to_string()]),
    ("b".to_string(), vec!["2".to_string()]),
]);
let input_str = serde_json::to_string(&inputs).unwrap();

// Prepare zkey path
let zkey_path = "./test-vectors/multiplier2_final.zkey".to_string();

// Generate proof
let result = CircomProver::prove(
    ProofLib::Rapidsnark,
    WitnessFn::WitnessCalc(multiplier2_witness),
    input_str,
    zkey_path.clone(),
)
.unwrap();

Proof Verification

// Verify proof
let valid = CircomProver::verify(
    ProofLib::Rapidsnark,
    result,
    zkey_path,
).unwrap();

Adapters

Witness Generation

• Rust Witness
• Witnesscalc adapter
• circom witnesscalc

Proof Generation

• Arkworks
• Rust rapidsnark

Performance

It speeds up circom proof by ~100x comparing to arkworks-rs/circom-compat in keccak256 circuits. We will provide more benchmarks with different adapters in the future. And you can also check the Mopro documentation for more benchmarks.

Community

• X account:
• Telegram group:
• Mopro Documentation: https://zkmopro.org

Acknowledgements

This work is sponsored by PSE.