Groth16 Prover

Currently, due to the Circom native C++ witness generator that depends on x86 assembly for field operations, only x86 architecture is supported.

This directory contains utilities for performing a "stark2snark" workflow. This is useful for transforming a RISC Zero STARK proof into a Groth16 SNARK proof which is suitable for publishing on-chain.

Recommended way to produce Groth16 receipts is to use the Prover trait in the risc0-zkvm crate. See the crate documentation for more information.

Quickstart

To install the necessary dependencies, run:

./scripts/install_prover.sh

Manual Installation

All the following commands must be run from the groth16_proof directory.

1. Run the ceremony (optional):

   wget -O groth16/pot23.ptau https://hermez.s3-eu-west-1.amazonaws.com/powersOfTau28_hez_final_23.ptau
   docker build -f docker/ceremony.Dockerfile . -t snark-ceremony
   docker run --rm -v $(pwd)/groth16:/ceremony/groth16 snark-ceremony

2. Build the prover image:

   docker build -f docker/prover.Dockerfile . -t risc0-groth16-prover

   Note that the prover.Dockerfile downloads a proving key from an existing ceremony. If a new ceremony is required, replace it with the new proving key generated in step 1.

Proof Generation

The input.json file needs to be generated using the seal-to-json utility. Place this file into the directory of your choice, then add this as a volume and run the docker container:

docker run --rm -v $WORK_DIR:/mnt risc0-groth16-prover

The resulting proof.json file will be in the chosen $WORK_DIR. This file can be parsed and decoded into a risc0_groth16::Seal. Finally, this seal can be embedded within a InnerReceipt::Groth16.

See risc0-zkvm/src/host/server/prove/tests.rs for an end-to-end example.