Rijndael 实现中的输出长度异常

Question

我在使用 BouncyCastle API for Java 实现 Rijndael 加密时遇到问题。

当我执行cipher.doFinal(inputTextBytes, intOutOff); 时，我得到了OutputLengthException：

org.bouncycastle.crypto.OutputLengthException: 输出缓冲区太短

我不完全理解如何生成该整数来执行doFinal() 方法。

这是我尝试过的：

public class RijndaelAndRFC2899Implementation {

    final static String WORD = "763059";
    final static String PASSWORD = "515t3ma5m15B4d35";
    final static byte[] SALT = new byte[]{1, 2, 3, 4, 5, 6, 7, 8};
    final static int KEY_SIZE = 256;
    final static int BLOCK_SIZE = 128;
    final static int ITERATIONS = 1000;

    public static void main(String[] args) throws Exception {
        BufferedBlockCipher cipher = getCipher(PASSWORD, true);
        byte[] inputText = WORD.getBytes("UTF-8");
        byte asd[] = new byte[cipher.getOutputSize(inputText.length)];
        int l = cipher.processBytes(inputText, 0, inputText.length, asd, 0);
        int n = cipher.doFinal(inputText, l); //<---HERE PRODUCES OutputLengthException
    }

    private static BufferedBlockCipher getCipher(String password, boolean encrypt) throws Exception {
        MessageDigest md = MessageDigest.getInstance("SHA-256");
        md.update(password.getBytes("UTF-8"));
        byte[] newPassword = md.digest();

        PKCS5S2ParametersGenerator generator = new PKCS5S2ParametersGenerator();
        generator.init(newPassword, SALT, ITERATIONS);

        ParametersWithIV iv = ((ParametersWithIV) generator.generateDerivedParameters(KEY_SIZE, BLOCK_SIZE));

        RijndaelEngine engine = new RijndaelEngine();
        BufferedBlockCipher cipher = new PaddedBufferedBlockCipher(new CBCBlockCipher(engine));   
        cipher.init(encrypt, iv);

        return cipher;
    }

}

你能帮我理解我做错了什么吗？

Answer 1

对doFinal() 的调用应该将输出数组作为第一个参数 - 而不是您正在处理的输入：

public static void main(String[] args) throws Exception {
    BufferedBlockCipher cipher = getCipher(PASSWORD, true);
    byte[] inputText = WORD.getBytes("UTF-8");
    byte asd[] = new byte[cipher.getOutputSize(inputText.length)];
    int l = cipher.processBytes(inputText, 0, inputText.length, asd, 0);
    int n = cipher.doFinal(asd, l); // <--- Change to asd
}

（我还没有验证其余的实现！）