bech32-js.js

var ALPHABET = 'qpzry9x8gf2tvdw0s3jn54khce6mua7l'

var ALPHABET_MAP = {}
for (var z = 0; z < ALPHABET.length; z++) {
  var x = ALPHABET.charAt(z)
  ALPHABET_MAP[x] = z
}

function polymodStep (pre) {
  var b = pre >> 25
  return ((pre & 0x1FFFFFF) << 5) ^
    (-((b >> 0) & 1) & 0x3b6a57b2) ^
    (-((b >> 1) & 1) & 0x26508e6d) ^
    (-((b >> 2) & 1) & 0x1ea119fa) ^
    (-((b >> 3) & 1) & 0x3d4233dd) ^
    (-((b >> 4) & 1) & 0x2a1462b3)
}

function prefixChk (prefix) {
  var chk = 1
  for (var i = 0; i < prefix.length; ++i) {
    var c = prefix.charCodeAt(i)
    if (c < 33 || c > 126) return 'KO';

    chk = polymodStep(chk) ^ (c >> 5)
  }
  chk = polymodStep(chk)

  for (i = 0; i < prefix.length; ++i) {
    var v = prefix.charCodeAt(i)
    chk = polymodStep(chk) ^ (v & 0x1f)
  }
  return chk
}

function checkbech32 (str) {
  var LIMIT = 90;
  if (str.length < 8) return 'KO';
  if (str.length > LIMIT) return 'KO';


  var split = str.lastIndexOf('1')
  if (split === -1) return 'KO';
  if (split === 0) return 'KO';

  var prefix = str.slice(0, split)
  var wordChars = str.slice(split + 1)
  if (wordChars.length < 6) return 'KO';

  var chk = prefixChk(prefix);
  if (typeof chk === 'string') return 'KO';

  var words = []
  for (var i = 0; i < wordChars.length; ++i) {
    var c = wordChars.charAt(i)
    var v = ALPHABET_MAP[c]
    if (v === undefined) return 'KO';
    chk = polymodStep(chk) ^ v

    // not in the checksum?
    if (i + 6 >= wordChars.length) continue
    words.push(v)
  }

  if (chk !== 1) return 'KO';
  return 'OK';
}