after_len method

Uint8List after_len(
  1. Uint8List message,
  2. int moff,
  3. int mlen,
  4. Uint8List theNonce,
)

Implementation

Uint8List after_len(
    Uint8List message, final int moff, final int mlen, Uint8List theNonce) {
  // check message
  if (!(message != null &&
      message.length >= (moff + mlen) &&
      theNonce != null &&
      theNonce.length == nonceLength)) return null;

  // message buffer
  Uint8List m = Uint8List(mlen + zerobytesLength);

  // cipher buffer
  Uint8List c = Uint8List(m.length);

  for (int i = 0; i < mlen; i++) m[i + zerobytesLength] = message[i + moff];

  if (0 !=
      TweetNaclFast.crypto_box_afternm(c, m, m.length, theNonce, _sharedKey))
    return null;

  // wrap byte_buf_t on c offset@boxzerobytesLength
  ///return new byte_buf_t(c, boxzerobytesLength, c.length-boxzerobytesLength);
  Uint8List ret = Uint8List(c.length - boxzerobytesLength);

  for (int i = 0; i < ret.length; i++) ret[i] = c[i + boxzerobytesLength];

  return ret;
}