ecrecover_test.js

// requires ethereumjs-util and ethers, 3rd party npm packages.

/* 
Ran on macbook with these results:

10000 ran with 0 errors.

real	0m28.769s
user	0m28.301s
sys	0m0.246s
*/

var ethUtil = require('ethereumjs-util')
var ethers = require('ethers')

var ecprivkey = Buffer.from('0123456789012345678901234567890123456789012345678901234567890123', 'hex')
var pubAddr = "0x14791697260E4c9A71f18484C9f997B308e59325"

var errors = 0
var numOfTests = 10000

for(i = 0; i < numOfTests; i++){
  var testMsg = Math.random().toString(36).substring(7)
  //console.log(testMsg)
  var hash = ethUtil.keccak(ethUtil.toBuffer(testMsg))
  var signed = ethUtil.ecsign(hash, ecprivkey)
  signed.r = toHexString(signed.r)
  signed.s = toHexString(signed.s)
  // subtract 27 so v is either 0 or 1
  signed.v = (signed.v - 27)
  //console.log(signed)
  var recoveredAddr = ethers.SigningKey.recover(hash, signed.r, signed.s, signed.v)
  //console.log(recoveredAddr)
  if(recoveredAddr != pubAddr) {
    errors = errors + 1
    console.log("ERROR: recovered address does not match the address of the signing private key")
  }
}

console.log(numOfTests + " ran with " + errors + " errors.")

// https://stackoverflow.com/questions/34309988/byte-array-to-hex-string-conversion-in-javascript
function toHexString(byteArray) {
  return "0x" + Array.from(byteArray, function(byte) {
    return ('0' + (byte & 0xFF).toString(16)).slice(-2);
  }).join('')
}