DEX RNG

DexRNG.sol is a permissionless random number generator contract. It uses the total reserve value of Uniswap and Sushiswap pairs as a source of randomness.

The primary random number function of the contract is

getRandomNumber(uint range) external returns(uint randomNumber, bool acceptableEntropy)

On every getRandomNumber call, the contract queries the total reserve value of the DEX pairs to use in its generation of a random number.

The contract treats a random number as generated with "acceptable entropy" if the reserve value of at least one of the DEX pairs used in the generation has updated since the previous call to the random number function.

The EAO / contract calling getRandomNumber is left to handle the acceptableEntropy value as it pleases.

Rolling Bounty

NFT Labs is offering a bounty of up to (tbd) in ETH to those who satisfy the bounty parameters.

We are privy of common RNG contract exploits and understand that DexRNG is vulnerable to the same. The purpose of this bounty is to discover how costly it is to exploit the DexRNG contract.

The bounty shall be awarded to those who submit an exploit setup that can reliably predict the random number generated by the DexRNG contract, for any given Ethereum mainnet block.

Details about the bounty, such as how to receive it, can be found on the bounty's Gitcoin page or Notion doc.

Run Locally

Clone the project

  git clone https://github.com/nkrishang/dex-rng.git

Install dependencies

  yarn install

Running Tests

To run hardhat tests, run the following command

npx hardhat test

The tests in test/ serve the following purpose:

• contract.js tests contract state changes.
• gas.js prints the estimated gas consumption of the contract functions. The test prints the gas consumption of calling getRandomNumber with up to 6 DEX pairs.
• healthCheck.js prints the randomNumber and acceptableEntropy values for the 10 most recent mainnet blocks.

The tests use hardhat's mainnet-forking feature. You will require provider API keys to successfully run the tests. The project uses Alchemy as a provider.

Deployment

To deploy this project on a given network (e.g. mainnet) update the hardhat.config.js as follows:

module.exports = {
  solidity: "0.8.0",
  networks: {
    mainnet: {
      url: `https://eth-mainnet.alchemyapi.io/v2/${ALCHEMY_API_KEY}`,
      accounts: [`${TEST_PRIVATE_KEY}`]
    }
  }
};

After updating the config file, run

  npx hardhat run scripts/deploy.js --network mainnet

Feedback

If you have any feedback, please reach out to us at krishang@nftlabs.co or support@nftlabs.com

Contributors

• @nkrishang

License

MIT