pad method
Implementation
Uint8List pad({required Uint8List data, int blockSize = AES_BLOCK_SIZE}) {
_log.finest("Padding data with zeros to block size: $blockSize");
_log.sdVerbose("Data to pad: ${data.hex()} ");
final padLength = blockSize - (data.length % blockSize);
List<int> list = data.toList()..addAll(List.filled(padLength, 0));
return Uint8List.fromList(list);
}