Ethers signs my request with a different from address

Hi, I am trying to sign a request with ethers using serialize.

This is my code

const { utils } = require('ethers');
const bn = require('bignumber.js');
const { serializeTransaction, parseEther } = utils;
const tx2 = require('ethereumjs-tx');
async function serialize1() {
        const wei = parseEther('0.02');
        console.log(wei);
        const gasPrice = '0x' + (2000000000).toString(16);
        console.log(gasPrice);
        const tx = {
                gasPrice: gasPrice,
                gasLimit: 21000,
                to: '0x3e245df5a4de41e65cecd1f98b96ca06c3d319f0',
                value: wei,
                nonce: 0,
                data: '',
                chainId: 3,
        };
        const serializedTransaction = await serializeTransaction(tx);
        console.log(serializedTransaction);
        const signature = 'c4b71f516c36468022d61b0e22016c6bc69bc2c99666fb7e63e3d04841c82ff53d5c687ebe43b290d03caa6766e8e957192faa6b360f4102b536c54c3318304f1b';
        console.log('---------------------------------------------');
        const signedSerialized = await serializeTransaction(tx, Buffer.from(signature, 'hex'));
        console.log(signedSerialized);
}

serialize1();

The signature (in hex) is for the address: 0x518171C334AD3adc1cF990A884D67963201B675F but the function returns 0xf86a808477359400825208943e245df5a4de41e65cecd1f98b96ca06c3d319f087470de4df8200008029a0c4b71f516c36468022d61b0e22016c6bc69bc2c99666fb7e63e3d04841c82ff5a03d5c687ebe43b290d03caa6766e8e957192faa6b360f4102b536c54c3318304f which when decoded is

{
  "nonce": 0,
  "gasPrice": 2000000000,
  "gasLimit": 21000,
  "to": "0x3e245df5a4de41e65cecd1f98b96ca06c3d319f0",
  "value": 20000000000000000,
  "data": "",
  "from": "0x0d67ffdd9b1d8858582d903bf0093e22b9da682e",
  "r": "c4b71f516c36468022d61b0e22016c6bc69bc2c99666fb7e63e3d04841c82ff5",
  "v": "29",
  "s": "3d5c687ebe43b290d03caa6766e8e957192faa6b360f4102b536c54c3318304f"
}

Here the from address shown is 0x0d67ffdd9b1d8858582d903bf0093e22b9da682e What I want to know is that what I am feeding into the serializeTransaction function is of the correct format or not? Does it need to go through any thing else when getting the final signed transaction? Am I using the function correctly?

[codemaster101]

Yo ricmoooooooooooo you’re a legend. I was supposed to pass the keccack of the transaction before sending it to the sign_ecdsa.

[ricmoo]

Yeah, my hunch is that you are not signing what you think you are signing. The ECDSA algorithm can only sign a 256-bit number, so usually data is hashed.

In the case of a transaction, the keccak256 of the unsigned, serialized transaction is hashed, depending on whether EIP-155 is in use or not, will dictate whether it is 6 RLP encoded fields or 9, which includes an encoded chain ID and 2 null data sets.

In the case of a message, it is prefixed with a preamble strong, and then the utf-8 bytes are hashed and this is signed.

So, you need to look up sign_ecdsa and see how it processes bytes. If it expects a digest, it may be truncating for example, which is not what you want to happen. If too short it might be padding. Whatever that method does, I think it is not doing what you need. 😃