Recover address from Ethereum message

secp256k1_ec_recover.js

#!/usr/bin/env node

const { utils } = require('ethers');
const secp256k1 = require('secp256k1');

function ethereumMessage(str) {
    const data = Buffer.from(str, 'utf8');
    const prefix = Buffer.from(
      `\u{19}Ethereum Signed Message:\n${data.length}`,
      'utf8',
    );
    return Buffer.concat([prefix, data]);
}

function hexToBuffer(str) {
    return Buffer.from(str.replace('0x', ''), 'hex');
}

function bufferToHex(buf) {
    return Buffer.from(buf).toString('hex');
}

function ecRecoverTest() {
    const data = "Some message";
    const message = ethereumMessage(data);
    const hashStr = utils.keccak256(message);
    // hash: 0x5a65edf40dec93b00ad4221fbe200e5c83006b6240f0fcf747be11b8de3d12ca
    const hash = hexToBuffer(hashStr)

    // signature(r,s,v) signed by Trust
    const signatureStr = "648a6169ea6a6b164dbcd85966aa341da8f63f4df132b00345b999515c929bc22ff02224c4e6319af82921394c6e6a0c4e139ca78bdd39406aeaa2d0ca93d28e1c";
    const signature = hexToBuffer(signatureStr);
    // recovery id - 27 for Ethereum
    const recovered = secp256k1.ecdsaRecover(signature.slice(0,64), signature[64] - 27, hash, false);
    console.log(bufferToHex(recovered));
    // uncompressed public key: 045ab29c3f44ee7a13302f42feff1f4f9527ddcbd0e9fb981cb9e70f8360c2b6a774959be65068c42f18cf4a921155b5c153e98892154c18f94ea36c9249d0b648

    const keyHash = utils.keccak256(Buffer.from(recovered).slice(1, 65))
    console.log(keyHash)
    // keccak256 hash: 0x3357503474a66aac8ad61ac17d8bf18c7ce84b3e175b339c4ca93aed1dd166f1
    
    // last 20 bytes is address without checksum
    const address = hexToBuffer(keyHash).slice(32 - 20, 32);
    console.log('0x' + bufferToHex(address));
    // address: 0x7d8bf18c7ce84b3e175b339c4ca93aed1dd166f1
}

ecRecoverTest();