Creating a transaction message for eth_sign

Question

I don't know how to create a transaction message for the method eth_sign (to, msg). I know that through eth_sign you can send a request for a transaction signature (in metamask for example), which will be passed in the msg parameter, which will be encoded through rlp. I don't understand how to implement all this.

Answer 1

There is a difference between a message and a transaction.

eth_sign is used for signing arbitrary messages (either text encoded to binary, serialized objects, or just any binary message), while eth_signTransaction and eth_sendTransaction is used for signing transaction objects.

MetaMask allows signing messages and returns the signature that can be used in your web app. But when it signs a transaction, it automatically broadcasts it and doesn't allow returning just the signed transaction.

If you want to sign a simple message, you can use the eth_sign method. Note that there are also newer methods such as personal_sign or signTypedData_v4.

let accounts = await ethereum.request({ method: 'eth_requestAccounts' });
// keccak256 hash of string "hello"
let messageHash = "0x1c8aff950685c2ed4bc3174f3472287b56d9517b9c948127319a09a7a36deac8";
let signature = await ethereum.request({ method: 'eth_sign', params: [accounts[0], messageHash] });
console.log(signature);

If you want MetaMask to sign and broadcast a transaction, you need to pass its object to the eth_sendTransaction method.

let accounts = await ethereum.request({ method: 'eth_requestAccounts' });
let txHash = await ethereum.request({
    method: 'eth_sendTransaction',
    params: [{
        from: accounts[0],
        to: "0xDeaDbeefdEAdbeefdEadbEEFdeadbeEFdEaDbeeF",
        value: "1" // 1 wei
    }],
});
console.log(txHash);