如何在Dart中填充cipher.doFinal（）方法所需的參數？

Question

我正在嘗試使用pointy_castle包在我的Flutter應用程序中進行加密，這類似於Java中的crypto.Cipher庫。 有一個名為doFinal()的方法，在Java中，您可以分配一個參數。 在Dart中，您必須分配四個參數。 那么我該如何正確填寫所需的參數呢？ 我需要一個如何做到這一點的例子。

在包docs中， doFinal(Uint8List inp, int inpOff, Uint8List out, int outOff) → int

這是Java中的代碼：

 ...
    byte[] encrypted;
    encrypted = cipher.doFinal(padString(text).getBytes());
    String finalData = bytesToHex(encrypted);
    return finalData;
 ...

在達特：

...
    Uint8List encrypted; // <- I have to make it of type Uint8List because _bytesToHex method requires looping through the list. However, it produces an error because of that: `A value of type 'int' can't be assigned to a variable of type 'Uint8List'.`
    encrypted = cipher.doFinal(utf8.encode(_padString(data))); // <- This produces an error since doFinal() requires 4 params.
    String finalData = _bytesToHex(encrypted);
    return finalData;
...

Answer 1

如果有人遇到過這種情況。 這就是我最終得到的結果：

import 'package:pointycastle/export.dart';

class Example {
  Uint8List encrypt(String data) {
    if (data == null || data.length == 0) return null;
    final Uint8List _key = utf8.encode('key');
    final Uint8List _iv = utf8.encode('iv');
    try {
      Uint8List encrypted;
      final CipherParameters params = PaddedBlockCipherParameters(
        ParametersWithIV(
          KeyParameter(_key),
          _iv,
        ),
        null,
      );
      final PaddedBlockCipherImpl cipher = PaddedBlockCipherImpl(
        PKCS7Padding(),
        CBCBlockCipher(
          AESFastEngine(),
        ),
      );
      cipher.init(true, params);
      encrypted = cipher.process(utf8.encode(data));
      return encrypted;
    } catch (_) {
      print(_);
      return null;
    }
  }

  String decrypt(Uint8List data) {
    if (data == null || data.length == 0) return null;
    final Uint8List _key = utf8.encode('key');
    final Uint8List _iv = utf8.encode('iv');
    try {
      final CipherParameters params = PaddedBlockCipherParameters(
        ParametersWithIV(
          KeyParameter(_key),
          _iv,
        ),
        null,
      );
      final PaddedBlockCipherImpl cipher = PaddedBlockCipherImpl(
        PKCS7Padding(),
        CBCBlockCipher(
          AESFastEngine(),
        ),
      );
      cipher.init(false, params);
      final String finalData = utf8.decode(cipher.process(data));
      return finalData;
    } catch (_) {
      print(_);
      return null;
    }
  }
}

感謝https://stackoverflow.com/users/9014097/topaco和https://github.com/Nguyenpk57的靈感。