Building with zkVerify: A Step-by-Step Guide to Scalable ZK Proof Verification

🚀 Introduction: Why zkVerify?

zkVerify is a modular blockchain built on Substrate, dedicated to efficiently verifying zero-knowledge proofs (ZKPs) off-chain and publishing attestations on-chain. It slashes verification costs by up to 50%+ compared to on-chain methods, enabling scalable dApps like zkRollups, private voting, and KYC systems.

Verify with Zero Knowledge

Key Innovations

• Proof Aggregation: Batch proofs into Merkle roots for cost-efficient on-chain verification.
• Multi-Prover Support: Groth16, Plonky2, Risc Zero, and more.
• Interoperability: Attestations are relayed to Ethereum, Base, and other EVM chains via smart contracts .

zkVerify Architecture

🔧 Core Components of zkVerify

1. Substrate-Based Blockchain

• L1 PoS Chain: Specialized for ZKP verification, powered by the tVFY token.
• Verifier Pallets: Modular pallets for different proof systems (e.g., Groth16, UltraPlonk).

2. Proof Submission Flow

1. Submit Proofs: Via zkverifyjs SDK or direct RPC calls.
2. Attestation Generation: Valid proofs are aggregated into Merkle roots and published on-chain.
3. On-Chain Verification: Contracts verify attestations using Merkle proofs.

3. SDK (zkverifyjs)

• Installation:

npm install zkverifyjs

• Key Features:
• Submit proofs (Groth16, Risc Zero, etc.) .
• Listen for attestation events (NewAggregationReceipt) .
• Register verification keys for reuse .

🛠 Step-by-Step: Verifying a Circom Proof

1. Circuit Setup

• Example Circuit: Poseidon hash verification in Circom:

template Example() { signal input a; // Private input signal input b; // Public hash component hash = Poseidon(1); hash.inputs[0] <== a; assert(b == hash.out); }

• Compile & Generate Proof: Use snarkjs to create proof.json and public.json.

2. Submit Proof via zkverifyjs

const { zkVerifySession } = require("zkverifyjs");
const session = await zkVerifySession.start()
  .Volta() // Testnet
  .withAccount("seed_phrase");

// Register verification key (Groth16)
const { events } = await session.registerVerificationKey()
  .groth16({ library: "snarkjs", curve: "bn128" })
  .execute(vkey);
// Submit proof
await session.verify()
  .groth16({ library: "snarkjs", curve: "bn128" })
  .execute({
    proofData: { proof, vk: vkeyHash, publicSignals },
    domainId: 0, // Target chain (e.g., Ethereum)
  });

• Listen for Attestation:

events.on("NewAggregationReceipt", (event) => { console.log("Attestation ID:", event.aggregationId); });

3. On-Chain Verification

• Smart Contract: Verify attestations using IVerifyProofAggregation.sol:

function verifyProof( uint256 domainId, uint256 aggregationId, bytes32 leaf, bytes32[] calldata merklePath ) external view returns (bool) { 
    return IVerifyProofAggregation(zkVerify).verifyProofAggregation( domainId, aggregationId, leaf, merklePath, leafCount, index );
 }

• Leaf Calculation:

bytes32 leaf = keccak256(abi.encodePacked( PROVING_SYSTEM_ID, // e.g., "groth16" vkeyHash, VERSION_HASH, keccak256(abi.encodePacked(publicInputs)) ));

🌐 Supported Chains & Use Cases

Deployed Networks

• Testnets: Sepolia, Base Sepolia, Arbitrum Sepolia.
• EVM Compatibility: Attestations are relayed via smart contracts.

Use Cases

1. zkRollups: Batch-verify transactions.
2. Private Voting: Prove eligibility without revealing identity.
3. KYC: Verify credentials off-chain.

📌 Key Takeaways

1. Cost Savings: zkVerify reduces gas costs by 50%+ for ZKP verification.
2. Modular Design: Supports multiple proving systems (Groth16, Plonky2, etc.).
3. SDK Integration: zkverifyjs simplifies proof submission and event listening.
4. On-Chain Verification: Use Merkle proofs to validate attestations.

Learn more:

• Explore the zkVerify Circom tutorial.
• Clone the EVM dApp example.