ripple-bs58check/index.js

A straightforward implementation of base58-check encoding

'use strict'

var base58 = require('ripple-bs58')
var createHash = require('create-hash')

// SHA256(SHA256(buffer))
function sha256x2 (buffer) {
  var tmp = createHash('sha256').update(buffer).digest()
  return createHash('sha256').update(tmp).digest()
}

// Encode a buffer as a base58-check encoded string
function encode (payload) {
  var checksum = sha256x2(payload)

  return base58.encode(Buffer.concat([
    payload,
    checksum
  ], payload.length + 4))
}

function decodeRaw (buffer) {
  var payload = buffer.slice(0, -4)
  var checksum = buffer.slice(-4)
  var newChecksum = sha256x2(payload)

  if (checksum[0] ^ newChecksum[0] |
      checksum[1] ^ newChecksum[1] |
      checksum[2] ^ newChecksum[2] |
      checksum[3] ^ newChecksum[3]) return

  return payload
}

// Decode a base58-check encoded string to a buffer, no result if checksum is wrong
function decodeUnsafe (string) {
  var buffer = base58.decodeUnsafe(string)
  if (!buffer) return

  return decodeRaw(buffer)
}

function decode (string) {
  var buffer = base58.decode(string)
  var payload = decodeRaw(buffer)
  if (!payload) throw new Error('Invalid checksum')
  return payload
}

module.exports = {
  encode: encode,
  decode: decode,
  decodeUnsafe: decodeUnsafe
}