convert method

Implementation

@override
Uint8List convert(List<int> message) {
  int i, j, n, m, pos;
  int h0, h1, h2, h3;
  int s0, s1, s2, s3;
  n = message.length;
  m = n + 16 - (n & 15);

  final output = Uint8List(m);
  final block32 = Uint32List(4); // 128-bit
  final iv32 = Uint32List.view(iv.buffer);
  final key32 = Uint32List.view(key.buffer);
  final block = Uint8List.view(block32.buffer);
  final output32 = Uint32List.view(output.buffer);
  final xkey32 = AESCore.$expandEncryptionKey(key32);

  s0 = iv32[0];
  s1 = iv32[1];
  s2 = iv32[2];
  s3 = iv32[3];

  // process 16-byte blocks
  for (i = 0; i + 16 <= n; i += 16) {
    h0 = (message[i + 0] ^
        (message[i + 1] << 8) ^
        (message[i + 2] << 16) ^
        (message[i + 3] << 24));
    h1 = ((message[i + 4]) ^
        (message[i + 5] << 8) ^
        (message[i + 6] << 16) ^
        message[i + 7] << 24);
    h2 = (message[i + 8] ^
        (message[i + 9] << 8) ^
        (message[i + 10] << 16) ^
        (message[i + 11] << 24));
    h3 = (message[i + 12] ^
        (message[i + 13] << 8) ^
        (message[i + 14] << 16) ^
        (message[i + 15] << 24));

    block32[0] = h0 ^ s0;
    block32[1] = h1 ^ s1;
    block32[2] = h2 ^ s2;
    block32[3] = h3 ^ s3;
    AESCore.$encryptLE(block32, xkey32);
    s0 = block32[0] ^ h0;
    s1 = block32[1] ^ h1;
    s2 = block32[2] ^ h2;
    s3 = block32[3] ^ h3;

    j = i >>> 2;
    output32[j + 0] = block32[0];
    output32[j + 1] = block32[1];
    output32[j + 2] = block32[2];
    output32[j + 3] = block32[3];
  }

  // process last block
  for (pos = 0; i + pos < n; ++pos) {
    block[pos] = message[i + pos];
  }
  if (padding.pad(block, pos)) {
    block32[0] ^= s0;
    block32[1] ^= s1;
    block32[2] ^= s2;
    block32[3] ^= s3;

    AESCore.$encryptLE(block32, xkey32);

    j = i >>> 2;
    output32[j + 0] = block32[0];
    output32[j + 1] = block32[1];
    output32[j + 2] = block32[2];
    output32[j + 3] = block32[3];

    i += 16;
    pos = 0;
  }

  if (pos != 0) {
    throw StateError('Invalid input size');
  }

  if (i == m) {
    return output;
  } else {
    return output.sublist(0, i);
  }
}