optimisation using hash precomputation

contracts/IPseudoRand.sol

@@ -21,6 +21,10 @@ interface IPseudoRand {
         bytes32 value;
     }
 
+    function hashToG1(
+        bytes memory message
+    ) external returns (Pairing.G1Point memory);
+
     function verifyPartialEvalFast(
         Pairing.G1Point memory h,
         Pairing.G1Point memory sigma,

contracts/PseudoRand.sol

@@ -12,6 +12,11 @@ contract PseudoRand is IPseudoRand{
     bytes public constant DOMAIN = bytes("DVRF pseudorandom generation 2023");
     uint public constant R = 21888242871839275222246405745257275088548364400416034343698204186575808495617;
 
+    function hashToG1(bytes memory message) public view returns (Pairing.G1Point memory) {
+        Pairing.G1Point memory h = Hash.hashToG1(DOMAIN, message);
+        return h;
+    }
+
     // verify partial eval without computing hash to point
     function verifyPartialEvalFast(
         Pairing.G1Point memory h,

contracts/zkdvrf_pre.sol

@@ -0,0 +1,286 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.0;
+
+import {Halo2Verifier} from "./Halo2Verifier.sol";
+import {GlobalPublicParams} from "./GlobalPublicParams.sol";
+import {Pairing} from "./libs/Pairing.sol";
+import {IPseudoRand} from "./IPseudoRand.sol";
+import {Grumpkin} from "./libs/Grumpkin.sol";
+
+import "@openzeppelin/contracts/utils/Strings.sol";
+import '@openzeppelin/contracts/access/Ownable.sol';
+
+// zkdvrf with precomputation for hash2curve
+contract zkdvrf_pre is Ownable {
+    using Strings for uint256;
+    using Grumpkin for *;
+
+    event RegistrationCompleted(uint32 count);
+    event NidkgStarted();
+    event NidkgCompleted(uint32 count);
+    event GlobalPublicParamsCreated();
+    event RandomInitiated(uint roundNum, string input);
+    event RandomThresholdReached(uint roundNum, string input);
+    event RandomReady(uint roundNum, string input);
+
+    struct dvrfNode {
+        address nodeAddress;
+        bool status;
+        uint256 deposit;
+        bool statusPP;
+        uint32 pkIndex;
+    }
+
+    enum Status {
+        Unregistered,
+        Nidkg,
+        NidkgComplete,
+        Ready
+    }
+
+    string public constant INPUT_PREFIX = "zkRand-v1-2024:";
+
+    uint32 public memberCount;
+    uint32 public threshold;
+    uint32 public ppLength;
+    // current count of members added
+    uint32 internal currentIndex;
+    // current count of members deposited and registered
+    uint32 internal registeredCount;
+    uint32 internal ppSubmissionCount;
+
+    uint256 public currentRoundNum;
+    uint256 public minNodeDeposit;
+
+    uint32 public pkListIndex;
+    Grumpkin.Point[] public pkList;
+    address[] public pkListOrder;
+
+    uint256[][] public ppList;
+  //  address[] public ppListOrder;
+
+    // The order in vkList is the same as pkList
+    Pairing.G1Point[] public vkList;
+    Pairing.G2Point internal gpkVal;
+
+    Status public contractPhase;
+    address public halo2Verifier;
+    address public halo2VerifyingKey;
+    address public globalPublicParams;
+    address public pseudoRand;
+
+    mapping (uint32 => address) public nodes;
+    mapping (address => dvrfNode) public addrToNode;
+    mapping (uint256 => string) public roundInput;
+    mapping (uint256 => Pairing.G1Point) public roundHash;
+    mapping (address => uint256) public lastSubmittedRound;
+    mapping (uint256 => mapping (uint32 => IPseudoRand.PartialEval)) public roundToEval;
+    mapping (uint256 => uint32) public roundSubmissionCount;
+    mapping (uint256 => IPseudoRand.PseudoRandom) public roundToRandom;
+
+
+    constructor(uint32 thresholdValue, uint32 numberValue, address halo2VerifierAddress, address halo2VerifyingKeyAddress, address globalPublicParamsAddress, address pseudoRandAddress, uint256 minDeposit) Ownable(msg.sender) {
+        require (halo2VerifierAddress != address(0) && globalPublicParamsAddress != address(0) && pseudoRandAddress != address(0), "Cannot be zero addresses");
+        memberCount = numberValue;
+        threshold = thresholdValue;
+        ppLength = 7 * memberCount + 14;
+        halo2Verifier = halo2VerifierAddress;
+        halo2VerifyingKey = halo2VerifyingKeyAddress;
+        globalPublicParams = globalPublicParamsAddress;
+        pseudoRand = pseudoRandAddress;
+        minNodeDeposit = minDeposit;
+    }
+
+
+    // works until all members added,
+    // to move to the next phase registeredCount has to be equal to memberCount
+    function addPermissionedNodes(address nodeAddress) public onlyOwner {
+        require(currentIndex < memberCount, "All members added");
+        require(nodeAddress != address(0), "Node cannot be zero address");
+        require(addrToNode[nodeAddress].nodeAddress == address(0), "Node has already been added");
+
+        addrToNode[nodeAddress] = dvrfNode(nodeAddress, false, 0, false, 0);
+        currentIndex++;
+    }
+
+    // each member registers with deposit and confirms
+    function registerNode(Grumpkin.Point memory pubKey) public payable {
+        require(contractPhase == Status.Unregistered, "Registration has already been completed");
+        require(msg.sender == addrToNode[msg.sender].nodeAddress, "Unauthorized call");
+        require(!addrToNode[msg.sender].status, "Node Already registered");
+        require(msg.value >= minNodeDeposit, "Must provide enough node deposit");
+        require(Grumpkin.isOnCurve(pubKey), "Invalid Public Key submitted");
+
+        nodes[registeredCount] = msg.sender;
+        addrToNode[msg.sender].deposit = msg.value;
+        addrToNode[msg.sender].status = true;
+        addrToNode[msg.sender].pkIndex = pkListIndex;
+        pkList.push(pubKey);
+        // pkListOrder is unutilized but added for public visibility
+        pkListOrder.push(msg.sender);
+        pkListIndex++;
+        registeredCount++;
+
+        // all the permitted nodes have registered
+        if (registeredCount == memberCount) {
+            emit RegistrationCompleted(registeredCount);
+        }
+    }
+
+    // owner starts nidkg protocol
+    // can't add members after this process
+    function startNidkg() public onlyOwner {
+        require(contractPhase == Status.Unregistered, "NIDKG has already been completed");
+        require(registeredCount == memberCount, "Not all Members are ready");
+        contractPhase = Status.Nidkg;
+
+        emit NidkgStarted();
+    }
+
+    // each member can submit pp_i, zk_i
+    // contract validates zk_i here for each submission and then accepts it
+    function submitPublicParams(uint256[] calldata pp, bytes calldata zkProof) public {
+        require(msg.sender == addrToNode[msg.sender].nodeAddress, "Unauthorized call");
+        require(contractPhase == Status.Nidkg, "Contract not in NIDKG phase");
+        require(!addrToNode[msg.sender].statusPP, "Node already submitted");
+        require(checkPublicParams(pp), "Invalid public parameters");
+        require(Halo2Verifier(halo2Verifier).verifyProof(halo2VerifyingKey, zkProof, pp), "SNARK proof verification failed");
+
+        addrToNode[msg.sender].statusPP = true;
+
+        ppList.push(pp);
+        // ppListOrder is unutilized but added for public visibility
+      //  ppListOrder.push(msg.sender);
+        ppSubmissionCount++;
+
+        if (ppSubmissionCount == memberCount) {
+            contractPhase = Status.NidkgComplete;
+            emit NidkgCompleted(ppSubmissionCount);
+        }
+    }
+
+    // compute gpk and vk and store on the contract
+    function computeVk(Pairing.G2Point calldata gpk) public {
+        require(contractPhase == Status.NidkgComplete, "Partial Parameter submission not complete");
+        (Pairing.G2Point memory gpkRet, Pairing.G1Point[] memory vk) = GlobalPublicParams(globalPublicParams).createGpp(memberCount, gpk, ppList);
+        for (uint i = 0; i < vk.length; i++) {
+            vkList.push(vk[i]);
+        }
+        gpkVal = gpkRet;
+        contractPhase = Status.Ready;
+
+        emit GlobalPublicParamsCreated();
+    }
+
+    // initiate public inputs for generating randoms
+    function initiateRandom() public onlyOwner {
+        require(contractPhase == Status.Ready, "Contract not ready");
+
+        if (currentRoundNum != 0) {
+            require(roundToRandom[currentRoundNum].value != bytes32(0), "Earlier round not completed");
+        }
+
+        currentRoundNum++;
+        bytes memory input = abi.encodePacked(INPUT_PREFIX, currentRoundNum.toString());
+        roundInput[currentRoundNum] = string(input);
+        roundHash[currentRoundNum] = IPseudoRand(pseudoRand).hashToG1(input);
+
+        emit RandomInitiated(currentRoundNum, roundInput[currentRoundNum]);
+    }
+
+    // each member can submit their partial evaluation.
+    // this function can be taken offchain. The onchain storage and verification can help determine which node to reward or punish.
+    function submitPartialEval(IPseudoRand.PartialEval memory pEval) public {
+        require(msg.sender == addrToNode[msg.sender].nodeAddress, "Unauthorized call");
+        // check valid round
+        require(roundToRandom[currentRoundNum].value == bytes32(0), "Round already computed");
+        // this will help revert calls if the contract status is not Ready and the first initiateRandom() is not called
+        require (lastSubmittedRound[msg.sender] < currentRoundNum, "Already submitted for round");
+        uint32 pkIndex = addrToNode[msg.sender].pkIndex;
+        require(pEval.indexPlus == pkIndex + 1);
+        Pairing.G1Point memory vkStored = vkList[pkIndex];
+        require(IPseudoRand(pseudoRand).verifyPartialEvalFast(roundHash[currentRoundNum], pEval.value, pEval.proof, vkStored), "Verification of partial eval failed");
+        lastSubmittedRound[msg.sender] = currentRoundNum;
+        roundToEval[currentRoundNum][pkIndex] = pEval;
+        roundSubmissionCount[currentRoundNum]++;
+
+        if (roundSubmissionCount[currentRoundNum] == threshold) {
+            emit RandomThresholdReached(currentRoundNum, roundInput[currentRoundNum]);
+        }
+    }
+
+    // submit the final pseudorandom value which is computed by combining t partial evaluations offchain
+    function submitRandom(IPseudoRand.PseudoRandom memory pseudo) public onlyOwner {
+        require(roundToRandom[currentRoundNum].value == bytes32(0), "Answer for round already exists");
+        require(roundSubmissionCount[currentRoundNum] >= threshold, "Partial evaluation threshold not reached");
+        require(IPseudoRand(pseudoRand).verifyPseudoRandFast(roundHash[currentRoundNum], pseudo.proof, gpkVal), "Incorrect random submitted");
+        bytes32 value = keccak256(abi.encodePacked(pseudo.proof.x, pseudo.proof.y));
+        require(pseudo.value == value, "Incorrect pseudorandom value");
+        roundToRandom[currentRoundNum] = pseudo;
+
+        emit RandomReady(currentRoundNum, roundInput[currentRoundNum]);
+    }
+
+    function getLatestRandom() public view returns (IPseudoRand.PseudoRandom memory pseudo) {
+        if (roundToRandom[currentRoundNum].value != bytes32(0)) {
+            return roundToRandom[currentRoundNum];
+        }
+
+        if (currentRoundNum == 1) {
+            revert("Answer does not exist for the round yet");
+        }
+
+        return roundToRandom[currentRoundNum - 1];
+    }
+
+    function getRandomAtRound(uint256 roundNum) public view returns (IPseudoRand.PseudoRandom memory pseudo) {
+        if (roundToRandom[roundNum].value != bytes32(0)) {
+            return roundToRandom[roundNum];
+        }
+
+        revert("Answer does not exist for the round yet");
+    }
+
+    function checkPublicParams(uint256[] calldata pp) public view returns (bool) {
+        require(pkList.length == memberCount, "Not enough member public keys");
+
+        require(pp.length == ppLength, "Wrong size of public parameters");
+        if (pp.length != ppLength) {
+            return false;
+        }
+
+        // check if the last 2n elements in pp are public keys
+        uint j = pp.length - 2 * memberCount;
+        for (uint i = 0; i < memberCount; i++) {
+            require(pp[j] == pkList[i].x, "Wrong public key x");
+            require(pp[j+1] == pkList[i].y, "Wrong public key y");
+            if (pp[j] != pkList[i].x || pp[j+1] != pkList[i].y) {
+                return false;
+            }
+            j = j+2;
+        }
+
+        return true;
+    }
+
+    function getIndexPlus(address nodeAdress) public view returns (uint32) {
+        uint32 pkIndex = addrToNode[nodeAdress].pkIndex;
+        return pkIndex + 1;
+    }
+
+    function getPkList() public view returns (Grumpkin.Point[] memory) {
+        return pkList;
+    }
+
+    function getPpList() public view returns (uint256[][] memory) {
+        return ppList;
+    }
+
+    function getGpk() public view returns (Pairing.G2Point memory) {
+        return gpkVal;
+    }
+
+    function getVkList() public view returns (Pairing.G1Point[] memory) {
+        return vkList;
+    }
+}

hardhat.config.ts

@@ -38,6 +38,7 @@ module.exports = {
       }
     }],
     overrides: {
+      'contracts/GlobalPublicParams.sol': altCompilerSettings,
       'contracts/PseudoRand.sol': altCompilerSettings,
     },
     gasReporter: {