anchor.diff:    }
   
   
  -String saltData(String data, [String salt = ""]) {
  -    if (data == null || data == "") {
  +String saltData(String data, String salt) {
  +    if (data.isEmpty || salt.isEmpty) {
         return data;
  -    }
  -    if (salt == null) {
  -      salt = "";
       }
       String _data = data + salt;
       var sha256 = new MD5();
  
positive.code:     return hexString;
    }
  
  String createHash([String str = ""]) {
      if (str == null) {
        str = "";
      }
      MD5 sha256 = new MD5();
      sha256.add(str.codeUnits);
      var digest = sha256.close();
      var hexString = CryptoUtils.bytesToBase64(digest);
      return hexString;
  
negative.code: 
  String encrypt(String data, String key) {
      initSymCrypt();
      if (data == null || data.isEmpty) {
        return null;
      }
      Uint8List _key = new Uint8List.fromList(key.codeUnits);
  