EpochKeyVerifierHelper.sol

This smart contract is dedicated to verifying epoch key proofs. See IVerifier for more info.

Typescript/Javascript

epochKeyVerifierHelper.ts

import { deployVerifierHelper } from '@unirep/contracts/deploy'
import { defaultProver } from '@unirep/circuits/provers/defaultProver'
import { Circuit, EpochKeyProof } from '@unirep/circuits'

// deploys epoch key verifier helper contract
const epochKeyVerifierHelper = await deployVerifierHelper(accounts[0], Circuit.epochKey)

const r = await defaultProver.genProofAndPublicSignals(
  Circuit.epochKey,
  CircuitInputs // see @unirep/circuits to know the whole circuit inputs
)

const { publicSignals, proof } = new EpochKeyProof(
  r.publicSignals,
  r.proof
)

// fails or returns proof signals
const signals = await epochKeyVerifierHelper.verifyAndCheck(
  publicSignals,
  proof
) 

Solidity

App.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import { EpochKeyVerifierHelper } from '@unirep/contracts/verifierHelpers/EpochKeyVerifierHelper.sol';

contract App {
  // use the deployed helper
  EpochKeyVerifierHelper public helper;
  constructor(
    EpochKeyVerifierHelper _helper
  ) {
    helper = _helper;
  }

  // decode and verify the proofs
  // fails or returns proof signals
  function decodeAndVerify(
    uint256[] calldata publicSignals,
    uint256[8] calldata proof
  ) public view returns (EpochKeyVerifierHelper.EpochKeySignals memory) {
    return helper.verifyAndCheck(publicSignals, proof);
  }
}

decodeEpochKeySignals

Decode the public signals from an epoch key proof into named variables.

function decodeEpochKeySignals(uint256[] memory publicSignals)
    public
    pure
    returns (EpochKeySignals memory)

struct EpochKeySignals {
    bool revealNonce;
    uint8 nonce;
    uint48 epoch;
    uint160 attesterId;
    uint256 stateTreeRoot;
    uint256 epochKey;
    uint256 data;
}

verifyAndCheck

Verify an epoch key proof and validate the public signals against the onchain state. This function will revert if any inputs are invalid.

caution

This function does not require the epoch for the proof to be the current epoch. The user may generate a valid proof for a past epoch. If you require the proof to be for the current epoch you should add an additional check using attesterCurrentEpoch.

danger

This function does not verify that the attesterId is the same as the caller. Thus, we recommend that to either use verifyAndCheckCaller or to manually verify the attesterId

function verifyAndCheck(
    uint256[] calldata publicSignals,
    uint256[8] calldata proof
) public
  view
  returns (EpochKeySignals memory) 

verifyAndCheckCaller

Verify an epoch key proof and validate the public signals against the onchain state. This function will revert if any inputs are invalid. This is identical to verifyAndCheck but also checks that the caller is the attester.

caution

This function does not require the epoch for the proof to be the current epoch. The user may generate a valid proof for a past epoch. If you require the proof to be for the current epoch you should add an additional check using attesterCurrentEpoch.

function verifyAndCheckCaller(
    uint256[] calldata publicSignals,
    uint256[8] calldata proof
) public
  view
  returns (EpochKeySignals memory) 

danger

The helper is not connected to the Unirep.sol contract. Please manually check if the state tree root exists with attesterStateTreeRootExists.

1. Decode public signals

EpochKeyVerifierHelper.EpochKeySignals memory signals = verifier.decodeEpochKeySignals(publicSignals); 

2. Verify state tree root

require(
  unirep.attesterStateTreeRootExists(
    signals.attesterId, 
    signals.epoch, 
    signals.stateTreeRoot
  )
);