permit-712签名
来源于EIP2612提案,先看文档再做操作
https://eips.ethereum.org/EIPS/eip-2612
合约代码
支持permit-712的代币，DAI，它的核心签名方法代码如下
function permit(address holder, address spender, uint256 nonce, uint256 expiry,
bool allowed, uint8 v, bytes32 r, bytes32 s) external
{
bytes32 digest =
keccak256(abi.encodePacked(
"\x19\x01",
DOMAIN_SEPARATOR,
keccak256(abi.encode(PERMIT_TYPEHASH,
holder,
spender,
nonce,
expiry,
allowed))
));
require(holder != address(0), "Dai/invalid-address-0");
require(holder == ecrecover(digest, v, r, s), "Dai/invalid-permit");
require(expiry == 0 || now <= expiry, "Dai/permit-expired");
require(nonce == nonces[holder]++, "Dai/invalid-nonce");
uint wad = allowed ? uint(-1) : 0;
allowance[holder][spender] = wad;
emit Approval(holder, spender, wad);
}
查看全部代码，
https://etherscan.io/address/0x6b175474e89094c44da98b954eedeac495271d0f#code
钱包签名实现
主要讲解web3实现
看metaMask钱包官方文档
https://docs.metamask.io/guide/signing-data.html#sign-typed-data-v4
web3签名实现
web3签名实现
步骤1、获取 PERMIT_TYPEHASH、DOMAIN_SEPARATOR
先看合约代码，发现PERMIT_TYPEHASH、DOMAIN_SEPARATOR定义都有public修饰符，且PERMIT_TYPEHASH有默认值，DOMAIN_SEPARATOR在初始化时已经赋值
// --- EIP712 niceties ---
bytes32 public DOMAIN_SEPARATOR;
// bytes32 public constant PERMIT_TYPEHASH = keccak256("Permit(address holder,address spender,uint256 nonce,uint256 expiry,bool allowed)");
bytes32 public constant PERMIT_TYPEHASH = 0xea2aa0a1be11a07ed86d755c93467f4f82362b452371d1ba94d1715123511acb;
constructor(uint256 chainId_) public {
wards[msg.sender] = 1;
DOMAIN_SEPARATOR = keccak256(abi.encode(
keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"),
keccak256(bytes(name)),
keccak256(bytes(version)),
chainId_,
address(this)
));
}
获取方式1，通过rpc请求取合约数据，PERMIT_TYPEHASH、DOMAIN_SEPARATOR（建议）
const contract = new ClientContract(abi, '0x6b175474e89094c44da98b954eedeac495271d0f', 1)
const calls = [
contract.PERMIT_TYPEHASH(),
contract.DOMAIN_SEPARATOR(),
]
const [PERMIT_TYPEHASH, DOMAIN_SEPARATOR] = await multicallClient(calls)
//DOMAIN_SEPARATOR: 0xdbb8cf42e1ecb028be3f3dbc922e1d878b963f411dc388ced501601c60f7c6f7
//PERMIT_TYPEHASH: 0xea2aa0a1be11a07ed86d755c93467f4f82362b452371d1ba94d1715123511acb
获取方式2，通过web3Utils进行计算（特殊情况可以使用此方式获取，顺便了解web3获取的方式）
const PERMIT_TYPEHASH = Web3.utils.keccak256("Permit(address holder,address spender,uint256 nonce,uint256 expiry,bool allowed)")
const web3 = new Web3(window.ethereum)
const DOMAIN_SEPARATOR = Web3.utils.keccak256(
// 第一个参数数组是合约里面参数的数据类型，第二个参数与合约代码里的参数对应
web3.eth.abi.encodeParameters(['bytes32', 'bytes32', 'bytes32', 'uint256', 'address'], [
Web3.utils.keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"),
Web3.utils.keccak256('Dai Stablecoin'),//name
Web3.utils.keccak256('1'),//version
1,//chainId_
'0x6B175474E89094C44Da98b954EedeAC495271d0F'//合约地址
]))
//DOMAIN_SEPARATOR: 0xdbb8cf42e1ecb028be3f3dbc922e1d878b963f411dc388ced501601c60f7c6f7
//PERMIT_TYPEHASH: 0xea2aa0a1be11a07ed86d755c93467f4f82362b452371d1ba94d1715123511acb
对于合于名称，version，建议还是直接取合约数据(反正都要取合约数据，还是直接取计算好的hash更方便)
步骤2、获取structHash
先看合约代码获取部分
keccak256(abi.encode(PERMIT_TYPEHASH,holder,spender,nonce,expiry,allowed))
const digestHash = web3.utils.keccak256(web3.eth.abi.encodeParameters(['bytes32', 'address', 'address', 'uint256', 'uint256', 'bool'], [
PERMIT_TYPEHASH,
account,
TWTRDao.address,
nonce,
deadline,
buyTokenData.allowed]
))
web3代码
组合无限授权hash（如果你需要无限授权的话）
// 获取nonce
const tokenContract = new ClientContract(buyTokenData.abi, buyTokenData.address, ChainId.MAINNET)
const nonce = await multicallClient([
tokenContract.nonces(account)
]).then(data => data[0])
const digestHash = web3.utils.keccak256(web3.eth.abi.encodeParameters(['bytes32', 'address', 'address', 'uint256', 'uint256', 'bool'], [
PERMIT_TYPEHASH,
holder,//你的地址
spender,//授权给目标地址
nonce,//你在DAI里面的nonce
expiry,//授权到期时间
allowed,//填true表示无限授权
]
))
组合指定量授权的hash（如果你需要有限授权的话）
// 获取nonce
const tokenContract = new ClientContract(buyTokenData.abi, buyTokenData.address, ChainId.MAINNET)
const nonce = await multicallClient([
tokenContract.nonces(account)
]).then(data => data[0])
const digestHash = web3.utils.keccak256(web3.eth.abi.encodeParameters(['bytes32', 'address', 'address', 'uint256', 'uint256', 'uint256'], [
PERMIT_TYPEHASH,
holder,//你的地址
spender,//授权给目标地址
amount,//你要授权的数量
nonce,//你在DAI里面的nonce
expiry,//授权到期时间
]
))
步骤3、获取签名哈希 structHash
合约代码
bytes32 structHash =
keccak256(abi.encodePacked(
"\x19\x01",
DOMAIN_SEPARATOR,
keccak256(abi.encode(PERMIT_TYPEHASH,
holder,
spender,
nonce,
expiry,
allowed))
));
web3代码
const digest = web3.utils.soliditySha3(
{
type: 'string',
value: '\x19\x01'
},
{
type: 'bytes32',
value: DOMAIN_SEPARATOR
},
{
type: 'bytes32',
value: structHash
}
)
步骤4、钱包签名
const signatureHash = await web3.eth.sign(digest, account);
// 0x150b79625e7321efe7ffa86f7141aa5906b185795647e27e2236c36bc407f0932010e8089ad6bb4f96ed0ec297cf8dc5553091b0a91eb5e8abc4958d27e3ac6c1c
此步骤会弹出钱包签名，用户同意签名之后得出一大串加密哈希，我们需要的是 v, r, s 所以要解析签名
解析签名
import {fromRpcSig} from 'ethereumjs-util'
const signature = fromRpcSig(signature)
// 结果
//{
// r: "0x150b79625e7321efe7ffa86f7141aa5906b185795647e27e2236c36bc407f093"
// s: "0x2010e8089ad6bb4f96ed0ec297cf8dc5553091b0a91eb5e8abc4958d27e3ac6c"
// v: 28
// }
node签名
web3签名第四步替换为以下方法即可
//const {SigningKey} = require('@ethersproject/signing-key')
//signingKey.privateKey('0x........')
//const signature = SigningKey.signDigest(digest);
const SigningKey = new ethers.utils.SigningKey(私钥)
const signature = SigningKey.signDigest(digest);
// 结果
//{
// r: "0x150b79625e7321efe7ffa86f7141aa5906b185795647e27e2236c36bc407f093"
// s: "0x2010e8089ad6bb4f96ed0ec297cf8dc5553091b0a91eb5e8abc4958d27e3ac6c"
// v: 28
// }