decode static method

Uint8List decode(String base32)

Takes in a base32 string and decodes it back to a Uint8List that can be converted to a hex string using Crypto.bytesToHex().

Implementation

static Uint8List decode(String base32) {
  int index = 0, lookup, offset = 0, digit;
  Uint8List bytes = new Uint8List(base32.length * 5 ~/ 8);
  for (int i = 0; i < bytes.length; i++) {
    bytes[i] = 0;
  }

  for (int i = 0; i < base32.length; i++) {
    lookup = base32.codeUnitAt(i) - '0'.codeUnitAt(0);
    if (lookup < 0 || lookup >= _base32Lookup.length) {
      continue;
    }

    digit = _base32Lookup[lookup];
    if (digit == 0xFF) {
      continue;
    }

    if (index <= 3) {
      index = (index + 5) % 8;
      if (index == 0) {
        bytes[offset] |= digit;
        offset++;
        if (offset >= bytes.length) {
          break;
        }
      } else {
        bytes[offset] |= digit << (8 - index);
      }
    } else {
      index = (index + 5) % 8;
      bytes[offset] |= (digit >> index);
      offset++;

      if (offset >= bytes.length) {
        break;
      }

      bytes[offset] |= digit << (8 - index);
    }
  }
  return bytes;
}