Ethers 102

1. StaticCall
2. Identify ERC721 Contracts
3. Encode Calldata
4. Batch Wallet Generation
5. Batch Transfer
6. Batch Collect
7. MerkleTree Script
8. Digital Signature Script
9. Listen to Mempool
10. Decode Transaction
11. Vanity Address Generator
12. Read Any Data
13. Front-running Script
14. Identify ERC20 Contracts
15. Flashbots
16. EIP712 Signature Script
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EIP712 Signature Script

I've been revisiting ethers.js recently to refresh my understanding of the details and to write a simple tutorial called "WTF Ethers" for beginners.

Twitter: @0xAA_Science

Community: Website wtf.academy | WTF Solidity | discord | WeChat Group Application

All the code and tutorials are open-sourced on GitHub: github.com/WTFAcademy/WTF-Ethers

In this tutorial, we will introduce how to use ethers.js to write an EIP712 signature script. Please refer to WTF Solidity 52: EIP712 for details on EIP712 contract.

EIP712

EIP712 Typed Data Signatures provides a more advanced and secure method for signatures. When a Dapp supporting EIP712 requests a signature, the wallet will display the original data of the signature message, allowing the user to verify the message data before signing.

EIP712 Signature Script

In this section, we will write a script to sign ERP712 signature.

  1. Create provider and wallet objects. In this example, we will use the private key of the Remix test wallet.

    // Connect to the Ethereum network using Infura or Alchemy's RPC endpoint
const SEPOLIA_TESTNET_URL = 'https://sepolia.infura.io/v3/8b9750710d56460d940aeff47967c4ba';
const provider = new ethers.JsonRpcProvider(SEPOLIA_TESTNET_URL);

// Create a wallet object using the private key and provider
const privateKey = 'cd82a7d0d6e528322e8c26f9ccbc18767543786d073c48ef38a753f29b1e8f39'
const wallet = new ethers.Wallet(privateKey, provider)

  2. Create the EIP712 Domain, which includes the contract's name, version (usually set to "1"), chainId, and verifyingContract (the address of the contract that verifies the signature).

    // Create the EIP712 Domain
let contractName = "EIP712Storage"
let version = "1"
let chainId = "1"
let contractAddress = "0xf8e81D47203A594245E36C48e151709F0C19fBe8"

const domain = {
    name: contractName,
    version: version,
    chainId: chainId,
    verifyingContract: contractAddress,
};

  3. Create the typed data for the signature message, where types declares the types, and message contains the data.

    // Create typed data, Storage
let spender = "0xD616f5A49571e7BCb1BB5326031bC8078BDA9Faa"
let number = "100"

const types = {
    Storage: [
        { name: "spender", type: "address" },
        { name: "number", type: "uint256" },
    ],
};

const message = {
    spender: spender,
    number: number,
};

  4. Call the signTypedData() signing method of the wallet object with the previously created domain, types, and message variables:

    // EIP712 signature
const signature = await wallet.signTypedData(domain, types, message);
console.log("Signature:", signature);
// Signature: 0xcd63049dd2388870f3fd18d00b36e1691971e4aea57369c45df2ba54b79853a16f02a71b71d71cf2d6ff01e3e679bc45633eedea64e54478c666a1f07bb5bf221c

  5. You can use the verifyTypedData() method to recover the signer address from the signature and message, and verify the validity of the signature. Typically, this step is executed in a smart contract.

    // Verify the EIP712 signature and recover the signer address from the signature and message
let eip712Signer = ethers.verifyTypedData(domain, types, message, signature)
console.log("EIP712 Signer: ", eip712Signer)
// EIP712 Signer: 0xD616f5A49571e7BCb1BB5326031bC8078BDA9Faa

Summary

In this tutorial, we have introduced how to write an EIP712 signature script using ethers.js.

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