Ultra Honk zk-SNARK Verifier

This repository contains an Ethereum-compatible zk-SNARK verifier smart contract implementing the Ultra Honk proving system, a test for that contract, and a Hardhat Ignition module that deploys that contract. It includes verification logic, custom field operations, elliptic curve utilities, and Fiat-Shamir transcript generation, all optimized for zero-knowledge proof verification in Solidity.

Try running some of the following tasks:

npx hardhat help
npx hardhat test
REPORT_GAS=true npx hardhat test
npx hardhat node
npx hardhat ignition deploy ./ignition/modules/Lock.js

🚀 Features

• zk-SNARK verifier for Ultra Honk
• Efficient finite field arithmetic (Fr) with modular inversion via precompiles
• Support for:
  • Permutation & lookup arguments
  • Arithmetic & delta range constraints
  • Elliptic curve and auxiliary relations
• Fiat-Shamir transcript generation
• G1 point compression & decompression for calldata-friendly proof parsing

🛠️ Structure

• FrLib: Finite field arithmetic over BN254 scalar field Fr.
• Honk: Data structures for proofs, verification keys, and challenges.
• TranscriptLib: Fiat-Shamir challenge generation from a zk-proof.
• RelationsLib: Evaluates relation constraints for proof verification.
• HonkVerificationKey: Hardcoded verification key for a specific circuit.
• pairing(...): Bilinear pairing checks using Ethereum's BN254 precompile.

📦 Prerequisites

To build or test this contract, you will need:

• Node.js (v16 or newer)
• Foundry or Hardhat
• solc version >=0.8.21
• Git

If you plan to test locally or simulate proof verifications, you'll also need:

• An Ethereum development node (e.g. Anvil)
• Sample proof and VK inputs (not included here)

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🔧 Installation

Clone this repository

git clone https://github.com/cypriansakwa/Ultra_Honk_zk-SNARK_Verifier.git
cd Ultra_Honk_zk-SNARK_Verifier

🧪 Usage

This contract is not meant to be deployed directly. Instead, it serves as a reference or dependency for a larger verifier system.

To verify a proof:

1. Load the verification key using HonkVerificationKey.loadVerificationKey().
2. Parse the proof bytes using TranscriptLib.loadProof(bytes).
3. Generate Fiat-Shamir challenges using TranscriptLib.generateTranscript(...).
4. Recompute and evaluate all constraints via RelationsLib.
5. Perform a final bilinear pairing check with pairing(...).

📦 Dependencies

• Solidity >=0.8.21
• No external libraries required (only Ethereum precompiles used)

🧩 Circuit Parameters

• Circuit size: 2^12 = 4096
• Number of public inputs: 0
• Constant parameters:
  • CONST_PROOF_SIZE_LOG_N = 28
  • NUMBER_OF_SUBRELATIONS = 26
  • NUMBER_OF_ENTITIES = 40
  • NUMBER_OF_ALPHAS = 25

📖 Reference

This contract is adapted from internal tooling at Aztec Protocol and reflects the Ultra Honk proving system described in their zk-SNARK architecture.