Verified Random Number Generator (vRNG)

ApeChain's vRNG is powered by Supra dVRF, a distributed and cryptographically verifiable randomness service. It enables smart contracts to request tamper-proof random numbers on-chain — suitable for NFT minting, gaming, lotteries, and any use case where provable fairness matters.

Contract addresses for ApeChain Mainnet and Testnet are listed on the Supra dVRF Available Networks ↗ (opens in a new tab) page.

Dev Guides

Advanced Example (with Custom Seed)

This example demonstrates requesting multiple random numbers with a custom client seed for additional entropy, and mapping results back to individual users.

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
 
interface ISupraRouter {
    function generateRequest(
        string memory _functionSig,
        uint8 _rngCount,
        uint256 _numConfirmations,
        uint256 _clientSeed,          // Optional: provide your own seed for extra entropy
        address _clientWalletAddress
    ) external returns(uint256);
}
 
contract Interaction {
    address supraAddr;
 
    constructor(address supraSC) {
        // Pass the ApeChain Mainnet Router address:
        // 0xf4966137dE4638Baa280ea35265B3AFEc5332df3
        supraAddr = supraSC;
    }
 
    mapping(uint256 => string) result;
    mapping(string => uint256[]) rngForUser;
 
    function exampleRequest(uint8 rngCount, string memory username) external {
        // Number of block confirmations before randomness is generated.
        // You can customize this value to meet your needs. Minimum: 1, Maximum: 20.
        uint256 numConfirmations = 1;
 
        uint256 nonce = ISupraRouter(supraAddr).generateRequest(
            "exampleCallback(uint256,uint256[])", // Must match callback signature exactly
            rngCount,
            numConfirmations,
            123,        // Custom client seed — replace with your own value (e.g. timestamp, UUID)
            msg.sender  // Must be your whitelisted wallet address
        );
 
        // Map the nonce to the username so the callback knows who to assign results to
        result[nonce] = username;
    }
 
    // Supra Router calls this automatically once randomness is ready
    function exampleCallback(uint256 nonce, uint256[] calldata rngList) external {
        // Security: only the Supra Router is allowed to call this function
        require(msg.sender == supraAddr, "only supra router can call this function");
 
        uint256[] memory x = new uint256[](rngList.length);
        rngForUser[result[nonce]] = x;
 
        for(uint8 i = 0; i < rngList.length; i++) {
            // Example: normalise each result to a value between 0–99
            rngForUser[result[nonce]][i] = rngList[i] % 100;
        }
    }
 
    // View the random results assigned to a username
    function viewUserName(string memory username) external view returns (uint256[] memory) {
        return rngForUser[username];
    }
}