anchor.diff:  
     Uint8List decrypt(dynamic data, dynamic key) {
       if (data is String) data = base64.decode(data);
  -    if (key is String) key = _toBytes(key);
  +    if (key is String) key = utf8.encode(key);
       if (data == null || data.length == 0) {
         return data;
       }
  
positive.code: |      Roger M. Needham                                    |
  |                                                          |
  | Code Author: Ma Bingyao <mabingyao@gmail.com>            |
  | LastModified: Oct 16, 2018                               |
  |                                                          |
  \*________________________________________________________*/
  library xxtea;
  
negative.code:       k.setAll(0, key);
        return k;
      }
      return key.sublist(0, 16);
    }
  
    int _int(int i) {
  