Random¶
链上伪随机数¶
使用哈希函数以上生成随机数的参数都是公开且可以预测的,所以这种方法是不安全的。
function getRandomOnchain() public view returns(uint256) {
bytes32 randomBytes = keccak256(
abi.encodePacked(
block.number,
msg.sender,
blockhash(block.timestamp - 1)
)
);
return uint256(randomBytes)
}
VRF¶
Chainlink 提供了可验证随机函数(Verifiable Randomness Function)
V2 版本取代并增强了 V1 版本,但 V1 版本仍可测试使用,示例如下
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.7;
import "@chainlink/contracts/src/v0.8/VRFConsumerBase.sol";
/**
* Code: https://github.com/smartcontractkit/chainlink-mix/blob/b0ffaff2a53e21a8d6113af4e55bafb471d7a371/contracts/VRFConsumer.sol
* Video: https://www.youtube.com/watch?v=JqZWariqh5s&ab_channel=Chainlink
* Get testnet LINK: https://faucets.chain.link/
*/
contract RandomNumberConsumer is VRFConsumerBase {
event RequestFulfilled(bytes32 requestId, uint256 randomness);
bytes32 internal keyHash;
uint256 internal fee;
uint256 public randomResult;
/**
* Constructor inherits(继承) VRFConsumerBase
*
* Network: Goerli
* Chainlink VRF Coordinator address: 0x2bce784e69d2Ff36c71edcB9F88358dB0DfB55b4
* LINK token address: 0x326C977E6efc84E512bB9C30f76E30c160eD06FB
* Key Hash: 0x0476f9a745b61ea5c0ab224d3a6e4c99f0b02fce4da01143a4f70aa80ae76e8a
*/
constructor()
VRFConsumerBase(
0x2bce784e69d2Ff36c71edcB9F88358dB0DfB55b4, // VRF Coordinator 地址
0x326C977E6efc84E512bB9C30f76E30c160eD06FB // 对应网络的 LINK Token 地址
)
{
keyHash = 0x0476f9a745b61ea5c0ab224d3a6e4c99f0b02fce4da01143a4f70aa80ae76e8a; // 随机公钥
fee = 0.1 * 10 ** 18; // VRF 请求需要消耗 0.1 LINK (Varies by network)
}
/**
* Requests randomness
*
* 在返回随机数前不要重复请求
*/
function getRandomNumber() public returns (bytes32 requestId) {
// 需要向部署后的合约中充值足够的LINK(确认钱包中的LINK币合约地址是否与上面的一致)
require(LINK.balanceOf(address(this)) >= fee, "Not enough LINK - fill contract with faucet");
return requestRandomness(keyHash, fee);
}
/**
* Callback function used by VRF Coordinator
*
* 生成的随机数randomness是uint256的,可能需要自行处理
*/
function fulfillRandomness(bytes32 requestId, uint256 randomness) internal override {
randomResult = (randomness % 50) + 1; // 1~50之间的随机数
emit RequestFulfilled(requestId, randomness);
}
// function withdrawLink() external {} - Implement a withdraw function to avoid locking your LINK in the contract
}
RNG¶
Random Number Generation