Truffle console commands - Learning how to sign a message using a private key and restore the address from hashed message

signandrecoveraddress.js

var ethUtil = require('ethereumjs-util')

var data = 'Hello World!'
var message = new Buffer(data)
var msgHash = ethUtil.hashPersonalMessage(message)
// privateKey = 0xc87509a1c067bbde78beb793e6fa76530b6382a4c0241e5e4a9ec0a0f44dc0d3 
// publicKey = 0x627306090abaB3A6e1400e9345bC60c78a8BEf57
var privateKey = new Buffer('c87509a1c067bbde78beb793e6fa76530b6382a4c0241e5e4a9ec0a0f44dc0d3', "hex")
var sig = ethUtil.ecsign(msgHash, privateKey)

var publicKey = ethUtil.ecrecover(msgHash, sig.v, sig.r, sig.s)
var sender = ethUtil.publicToAddress(publicKey)
console.log('publicKey = ', sender.toString('hex'))

var Web3 = require('web3');
var web3 = new Web3();
var ethUtil = require('ethereumjs-util');

// Private Key
var pKey = "c87509a1c067bbde78beb793e6fa76530b6382a4c0241e5e4a9ec0a0f44dc0d3"
var pKeyx = new Buffer(pKey, "hex")

// Shared Message
var message = 'Hello World!'
var messageHash = web3.utils.sha3(message)
var messageHashx = new Buffer(messageHash.replace("0x", ""), "hex")

// Signed Hash
var signedMessage = ethUtil.ecsign(messageHashx, pKeyx)
var signedHash = ethUtil.toRpcSig(signedMessage.v, signedMessage.r, signedMessage.s).toString("hex")
console.log('signedHash = ', signedHash)

// Recover Address
var sigDecoded = ethUtil.fromRpcSig(signedHash)
var recoveredPub = ethUtil.ecrecover(messageHashx, sigDecoded.v, sigDecoded.r, sigDecoded.s)
var recoveredAddress = ethUtil.pubToAddress(recoveredPub).toString("hex")
console.log('recoveredAddress = ', recoveredAddress)