Solidity Sign off-chain & Verify on-chain (EIP191 and EIP721)

This is a project which signs message off-chain and verifies signature on-chain inside Solidity code.

Prerequisites

Project setup

npm install

Compiles and hot-reloads for development

npm run serve

Now, you're ready to open http://localhost:8080/ on Chrome browser, and you can run it step by step for a clearly understanding.

Compiles and minifies for production

npm run build

EIP712

Send Email Contract Send Email Contract and Javascript Common Multiple Struct Contract Common Multiple Struct Contract and Javascript

EIP191

1. Connect With MetaMask

connectToMetamask: async function () {
    if (window.ethereum != undefined) {
        let accounts = await window.ethereum.enable();
        console.log("Your address: ", accounts);
        this.firstAccount = accounts[0]; 
    }
}

This will connect with MetaMask and get the account you selected from MetaMask Pop-up window.

2. Message hash

web3MessageHash: async function () {
    const info = this.getContractInfo();
    const rpcUrl = info[0]
    let web3 = new Web3(rpcUrl);
    
    const to = this.firstAccount;
    const _amount = 123 * 1e18;
    const _message = "Yidian Metaverse";
    const _nonce = 12;

    let result = web3.utils.soliditySha3(to, _amount, _message, _nonce);
    // or
    // let result = web3.utils.soliditySha3({t: 'address', v: to}, {t: 'uint256', v: _amount}, {t: 'string', v: _message}, {t: 'uint256', v: _nonce});
    
    this.messageHash = result;
}

This method will generate a hash string from the data you want to pack, it's only done locally.

3. Sign message hash in use of your private key

MetaMaskSignedMsgHash: async function () {
    let result = await window.ethereum.request({ method: "personal_sign", params: [this.firstAccount, this.messageHash]});
    console.log("Signature=", result)
    this.signedMessageHash = result;
}

This method will generate data sigature by using MetaMask so that users know how do we use their private key. or using a account_sign in web3.js

const web3 = new Web3(rpcUrl); 
const result2 = web3.eth.accounts.sign(this.messageHash, "your private key");
console.log("Signed Message hash in web3.js : ", result2)

4. Verify on Solidity

solVerify: async function () {
    const info = this.getContractInfo();
    const rpcUrl = info[0]
    const contractAddress = info[1]
    const contractAbi = info[2]

    const web3 = new Web3(rpcUrl);

    const to = this.firstAccount;
    const _amount = web3.utils.toHex(123 * 1e18);
    const _message = "Yidian Metaverse";
    const _nonce = 12;

    const myContract = new web3.eth.Contract(contractAbi, contractAddress);
    const result = await myContract.methods.verify(this.firstAccount, to, _amount, _message, _nonce, this.signedMessageHash).call();
    console.log("The Verification result：", result);
}

This is the PRC endpoint、contract address、and contract abi for the signature verification scenario.

getContractInfo: function () {
    const rpcUrl = "https://rinkeby.infura.io/v3/your-project-id";
    const contractAddress = "0xff0cC28F685b74AB46F724844B49Ff3E71eF65EC";

    const contractAbi = [{"inputs":[{"internalType":"bytes32","name":"_messageHash","type":"bytes32"}],"name":"getEthSignedMessageHash","outputs":[{"internalType":"bytes32","name":"","type":"bytes32"}],"stateMutability":"pure","type":"function"},{"inputs":[{"internalType":"address","name":"_to","type":"address"},{"internalType":"uint256","name":"_amount","type":"uint256"},{"internalType":"string","name":"_message","type":"string"},{"internalType":"uint256","name":"_nonce","type":"uint256"}],"name":"getMessageHash","outputs":[{"internalType":"bytes32","name":"","type":"bytes32"}],"stateMutability":"pure","type":"function"},{"inputs":[{"internalType":"bytes32","name":"_ethSignedMessageHash","type":"bytes32"},{"internalType":"bytes","name":"_signature","type":"bytes"}],"name":"recoverSigner","outputs":[{"internalType":"address","name":"","type":"address"}],"stateMutability":"pure","type":"function"},{"inputs":[{"internalType":"bytes","name":"sig","type":"bytes"}],"name":"splitSignature","outputs":[{"internalType":"bytes32","name":"r","type":"bytes32"},{"internalType":"bytes32","name":"s","type":"bytes32"},{"internalType":"uint8","name":"v","type":"uint8"}],"stateMutability":"pure","type":"function"},{"inputs":[{"internalType":"address","name":"_signer","type":"address"},{"internalType":"address","name":"_to","type":"address"},{"internalType":"uint256","name":"_amount","type":"uint256"},{"internalType":"string","name":"_message","type":"string"},{"internalType":"uint256","name":"_nonce","type":"uint256"},{"internalType":"bytes","name":"signature","type":"bytes"}],"name":"verify","outputs":[{"internalType":"bool","name":"","type":"bool"}],"stateMutability":"pure","type":"function"}];
    return [rpcUrl, contractAddress, contractAbi];
}