-PROOF OF CONCEPT // 3AM YOLO PUSH // UNOPTIMISED // UNAUDITED // DO NOT USE IN PROD // ET CETERA

RNGesus

RNGesus is the saviour to all EVM networks that lack infrastructure to provide verifiable randomness. Powered by drand.

Consuming contracts may request a random beacon from the future. A random beacon can be proved by anyone who can supply a valid SNARK proof of verification of the BLS signature for that round.

This project uses BLS12-381 verification circuits from 0xPARC's circom-pairing (forked here) project to (somewhat) efficiently perform BLS12-381 signature verification on the EVM.

Many optimisations can be made including adding a hash_to_field verification circuit so that this expensive operation does not need to be done in Solidity (would save ~850k gas).

Deployed addresses

Scroll Alpha

RNGesus: 0xb3a2EAB23AdC21eA78e1851Dd4b1316cb2275D9E

BLSSNARKVerifier: 0x9309bd93a8b662d315Ce0D43bb95984694F120Cb

Test random beacon proof tx: 0x14776cbe5e2999ffdc2b7ec71c3b708487e4c1ec9af3dbac1e5e462327a6441b

Base Goerli

RNGesus: 0xa6a10668c93d532643e2e4511c2e668537288643

BLSSNARKVerifier: 0xb3a2EAB23AdC21eA78e1851Dd4b1316cb2275D9E

Test random beacon proof tx: 0x1552867bfb9acb3d2326d01a90a6622cf96ca793e9ff7cfbefd1e0619d65c4cb

Aurora Testnet

RNGesus: 0xA6A10668c93d532643e2e4511c2E668537288643

BLSSNARKVerifier: 0xb3a2EAB23AdC21eA78e1851Dd4b1316cb2275D9E

Mantle Testnet

RNGesus: 0xb3a2EAB23AdC21eA78e1851Dd4b1316cb2275D9E

BLSSNARKVerifier: 0x9309bd93a8b662d315Ce0D43bb95984694F120Cb

Test random beacon proof tx: 0xd05493353faa39b2d68e669daa8ec18465bd40b832f9bc7a1426e18f6b380c5e

Requesting a random number

A contract that wants to receive a random number may request a random number from the RNGesus contract by calling the IRNGesus#requestRandomness(uint256 deadline) function. The deadline must be a future block timestamp. A prover will be able to fulfill this request with a random beacon from the nearest round on or after this deadline.

import { IRNGesus } from 'rngesus/contracts/interfaces/IRNGesus.sol';

contract Consumer {
    function begin(uint256 deadline) external {
        requestId = IRNGesus(rngesus).requestRandomness(deadline);
    }
}

The calling contract should also implement the IRandomnessReceiver interface in order to receive the random beacon after its validity has been proven.

import { IRandomnessReceiver } from 'rngesus/contracts/interfaces/IRandomnessReceiver.sol';

contract Consumer is IRandomnessReceiver {
    function receiveRandomness(uint256 rid, uint256 rand) external {
        require(requestId == rid, "Request ID didn't match");
        randomness = rand;
    }
}

Development

This project makes use of git submodules, which need to be initialised:

git submodule init
git submodule update

To install dependencies:

# Make sure yarn is installed
npm install -g yarn
# Install dependencies
yarn

Running tests:

yarn test