Create Ethereum Signatures

genSignature.js

const Web3 = require('web3')
const provider = new Web3.providers.HttpProvider('http://localhost:8545')
const web3 = new Web3(provider)

function toHex(str) {
 var hex = ''
 for(var i=0;i<str.length;i++) {
  hex += ''+str.charCodeAt(i).toString(16)
 }
 return hex
}

let addr = web3.eth.accounts[0]
let msg = 'I really did make this message'
let signature = web3.eth.sign(addr, '0x' + toHex(msg))
console.log(signature)