[NRG Proposal] Semaphore in Noir

[chancehudson]

This is a proposal to build a Semaphore implementation in Noir along with associated Javascript and Solidity bindings. The implementation will be compatible with the Semaphore v4 npm packages and circom circuits.

This proposal includes:

• Noir semaphore implementation
• Solidity verifier from the Barretenberg prover
• Javascript package/wrapper
• Demo web application using noir/circom circuits

Team members

Chance Hudson - former PSE engineer
Bhargav Annem - undergraduate at Caltech, former PSE grantee

Timeline

Weeks 1-2: Noir circuit with tests, Javascript bindings for calling/testing the noir circuit
Weeks 3-4: Javascript wrapper package, solidity verifier (both with tests against existing npm package)
Week 5: Demo application

Start date: flexible based on approval.

Detailed description

This section contains detailed descriptions of what is to be built and what will be changed in the Semaphore library.

Noir implementation

The Semaphore Noir implementation will live in it's own repository. We'll use the zk-kit.noir merkle tree implementation, and a jubjub key implementation based on jat9292/noir-elgamal. This is a small wrapper around the noir standard libraries.

A rough sample can be seen here.

This implementation will be tested against @semaphore-protocol/identity for compatibility.

Solidity implementation

The Solidity implementation will include a change to @semaphore-protocol/contracts. Specifically we'll modify SemaphoreProof to separate the public signals and the proof data. We'll make variants such as SemaphoreProofGroth16, SemaphoreProofUltraplonk, etc. with verification and validation functions in Semaphore.sol.

This implementation will include tests to generate and verify proofs from the Noir implementation above.

Javascript wrapper

We'll include a Javascript wrapper for generating Noir proofs with a similar api to @semaphore-protocol/proof. The delivered package should be suitable for integration into the semaphore-protocol monorepo.

Web demo

We'll include a web demo that generates a semaphore group, adds members, and generates membership proofs in browser. We'll deploy a Semaphore contract to the Sepolia testnet and allow the web demo to modify this contract arbitrarily.