ORAO zkVRF JS SDK

ORAO's Zero-Knowledge Verifiable Random Function (zkVRF) provides fast, secure and affordable randomness utiziling zero knowledge protocols. zkVRF utilizes zkSNARKs version of the Zero-knowledge proofs (ZKPs) family of probabilistic protocols. With zkVRF you can create unique NFT characteristics, generate random weapons and levels in games, provide unique loot boxes, enable provably fair rewards distribution, randomize airdrops and provide secure, verifiable lottery/raffle.

zkVRF is currently deployed to:

Network	OraoVRF
Avalanche Fuji	0x35d0a63c248490810705e895d1Ba4fD8fF454a19
Polygon Amoy	0x8587eBdBED9280A493d4105238b2b3e373931816
Zircuit Sepolia	0xDA2Fc58785B299b731174948D15E5959619d56d2
Arbitrum Sepolia	0x77B95E9e8203A4EEBF89664642f835b0C33F9416

Features

• ability to pre-pay for VRF requests (on-chain treasury per wallet)
• callback option
• gas setting for faster tx

Integration example

We've built a simple Solidity contract which mints an NFT with Random features. The source code is available here

Compile and deploy:

cd examples/sol
npm run compile
npm run deploy

Solidity example:

contract OraoVRFConsumer is OraoVRFConsumerBase {
  bytes32 public seed;
  bytes32 public part1;
  bytes32 public part2;
  IOraoVRF internal _vrfCoordinator;

  constructor(address vrfCoordinator) OraoVRFConsumerBase(vrfCoordinator) {
    _vrfCoordinator = IOraoVRF(vrfCoordinator);
  }
    
  function calcGasUsed() public override returns (uint256 gasUsed) {
    uint256 startGas = gasleft();

    fulfillRandomness(
      0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff,
      0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff,
      0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
    );

    gasUsed = startGas - gasleft();
  }
    
  function fulfillRandomness(bytes32 _seed, bytes32 _part1, bytes32 _part2) internal override {
    seed = _seed;
    part1 = _part1;
    part2 = _part2;
  }

  function request(bytes32 _seed) public payable override {
    seed = _seed;
    super.request(_seed);
  }
}

const provider = new ethers.providers.InfuraWebSocketProvider(
    "matic",
    process.env.INFURA_API_KEY
);
const wallet = new ethers.Wallet(process.env.PRIVATE_KEY, provider);
const signerAddress = wallet.address;
const oraoVrfConsumer = new ethers.Contract(
    ORAO_VRF_CONSUMER_ADDRESS,
    CONSUMER_ABI,
    signer
);

const gasPrice = await provider.getGasPrice();
const txValue = await oraoVrfConsumer.calcTxValue(gasPrice);

const seed = new Uint8Array(randomBytes(32));
await oraoVrfConsumer.request(seed, { value: txValue });