Randomness

Randomness is a difficult problem to solve in computer science. Due to blockchain's deterministic nature, it is even more difficult in blockchain projects.

In fact, it's no exaggeration to say that 100% secure randomness is impossible on the blockchain.

However, "almost secure" randomness could be usefull in most cases. This project's goal is having "almost secure" randomness on the blockchain.

How It Works

Some nice diagrams and explanations here...

Integration

Short hardhat example here...

Example Client Contract

//SPDX-License-Identifier: MIT
// contracts//ARandomness.sol
pragma solidity ^0.8.4;

import "./libraries/Randomness.sol";
import "./ARandomness.sol";
import "hardhat/console.sol";

contract ExampleClient is ARandomness {
    using Randomness for Randomness.RNG;
    Randomness.RNG internal rng;
    uint8 public currentRandom;

    constructor(uint256 _prime, uint16 _iterations)
        ARandomness(_prime, _iterations)
    {}

    // first step, creating seed, costs ether
    function generate() external payable {
        require(msg.value == 1 ether, "invalid payment");
        (, seeds[msg.sender]) = rng.getRandom();
    }

    // second step, proof should be generated on frontend side
    function use(uint256 _proof) external {
        require(_verify(_proof), "invalid proof");
        uint256 _randomness = _proof;
        uint256 _random;
        (_randomness, _random) = rng.getRandom(_proof, seeds[msg.sender]);
        console.log("here is your random number:", _random);
        (_randomness, _random) = rng.getRandomRange(0, 100, seeds[msg.sender]);
        console.log("here is another one between 0 and 100:", _random);
        currentRandom = uint8(_random);
    }
}

Deployment

await ethers.getContractFactory("ExampleClient", {
  libraries: {
    Randomness: randomnessFujiAddress,
  },
});

Contract Addresses

• Avalanche Fuji Testnet: 0xf4ff6bd06181f7893bfb5dd49abe9566ae37c736
• Binance Smart Chain Testnet: 0x177aba2adb7570c70ca3e2760cd89e1823c29450
• Polygon Mumbai Testnet: 0x177aba2adb7570c70ca3e2760cd89e1823c29450
• Avalanche C-Chain: 0x177aba2adb7570c70ca3e2760cd89e1823c29450
• Binance Smart Chain Mainnet: 0x177aba2adb7570c70ca3e2760cd89e1823c29450
• Polygon Mainnet: 0x177aba2adb7570c70ca3e2760cd89e1823c29450

Projects Using Randomness

• Randora

ps: you can create a pull request to add your project

Credits

The theoretical and practical background of this project is based on the following article by Justin Silver

• Provable Randomness with VDF by Justin Silver

Disclaimer

At the time of writing, there is no known successfull attack to this algorithm. But as mentioned before, blockchain is a deterministic environment. Please use this source for non-critical operations with your own risk.