zkAttestation

zkAttestation provides a demonstration of how zero-knowledge proofs can be submitted and verified for Noir projects through attestations. This repository showcases a command-line interface (CLI) executable that facilitates various operations outlined below.

Directory Structure

The repository is structured as a conventional Rust project. A dedicated circuit directory has been added, housing the Noir project files.

Setting up the circuit

You can check how to install nargo here. You can start with a clean Noir project.

rm -rf circuit
nargo new circuit

After you finished working on your circuit, make sure to run:

nargo check
nargo compile

You can now proceed to fill in your public and secret arguments in the Prover.toml file. This file is ignored by default. Then run:

nargo prove

This generates the proof that we'll submit.

Local Testing Environment

While the primary development environment for this project is a local network utilizing anvil or a hardhat node, adaptions can be made for testnet deployment with some adjustments.

The eas crate allows for interaction with the Ethereum Attestation Service contracts. To deploy them, use the command:

cargo run -- deploy

After running this we would get an output like this one:

EAS Contract: 0xe7f1725e7734ce288f8367e1bb143e90bb3f0512
Schema Registry: 0x5fbdb2315678afecb367f032d93f642f64180aa3
Schema ID: [232, 130, 60, 213, 42, 217, 24, 113, 178, 74, 194, 39, 104, 70, 212, 111, 139, 30, 76, 5, 150, 91, 62, 157, 172, 70, 157, 108, 122, 94, 15, 169]

Make sure to update your main.rs file with these values.

Executing the above will also create the zkAttestation attestation schema. This schema not only defines an interface for our attestations but also assigns a unique identifier to the project attestations. The schema is designed as:

bytes32 circuitId, bytes pubArgs, bytes proof

Proof Submission Process

Initiate your work on the Noir project within the circuit directory.
Upon completion, ensure that both circuit.proof and Verifier.toml files are generated.
Execute the attest command to submit the attestation:

cargo run -- attest

The submitted attestation will encapsulate:

circuit_id: [u8;32] - Represents the SHA2-256 hash derived from the circuit.json output file.
pub_param_bytes: [u8] - Byte-encoded version of the Verifier.toml file, comprising the public verification parameters.
proof_bytes: [u8] - Contains the generated proof.

Note: I included a separator between the public parameters and the proof to decode the byte array, since both are of arbitrary length. There may be a better way to decode this parameters.

Proof Verification Process

For entities interested in verifying the proof:

Clone the repository version containing the circuit.
Execute the verification command:

cargo run -- verify

Post the generation of proof and verifier files, transition to the circuit directory and initiate the final verification step:

cd circuit
nargo verify

Important Notes

This repository serves purely as a proof of concept.
It is not designed for deployment in production settings.
The current implementation accommodates only a single proof per circuit. While it downloads every proof, this design choice aims to exemplify how multiple proofs for a given circuit can be obtained and verified.