使用BouncyCastle的分组密码对字节数组进行加密/解密的最简单方法是什么？ [英] What is the simplest way to encrypt/ decrypt a byte array using BouncyCastle's block cipher?

问题描述

如果我有一个 BlockCipher 和一个 byte [] ，我是从获得的包含秘密消息的字符串，最简单的方法是获得 byte [] 个已加密消息的最简单方法？

If I have a BlockCipher and a byte[] that I got from a String containing a secret message, what's the easiest way to get a byte[] of the message encrypted?

在普通的Java API中，我可以执行 cipher.doFinal（secretMessage），但是这里似乎没有这样的东西，它

In the normal Java API, I could just do cipher.doFinal(secretMessage), but there doesn't seem to be anything like that here, it only processes blocks.

我知道我可以使用 BufferedBlockCipher ，但这仍然不能显着简化事情。

I know I can use a BufferedBlockCipher, but this still doesn't simplify things significantly. What's the easiest high-level way to use this cipher?

推荐答案

确定，因此，使用轻量级API和计数器模式是最简单的高级方法。您将获得的最简单和现代的模式之一：

OK, so using the lightweight API and counter mode, which is one of the easiest and modern modes you would get:

public class BouncyEncrypt {

    private static final int IV_SIZE = 16;

    public static void main(String[] args) throws Exception {
        // key should really consist of 16 random bytes
        byte[] keyData = new byte[256 / Byte.SIZE];
        KeyParameter key = new KeyParameter(keyData);

        byte[] ciphertext = encryptWithAES_CTR(key, "owlstead");
        System.out.println(decryptWithAES_CTR(key, ciphertext));
    }

    private static byte[] encryptWithAES_CTR(KeyParameter key, String in)
            throws IllegalArgumentException, UnsupportedEncodingException,
            DataLengthException {
        // iv should be unique for each encryption with the same key
        byte[] ivData = new byte[IV_SIZE];
        SecureRandom rng = new SecureRandom();
        rng.nextBytes(ivData);
        ParametersWithIV iv = new ParametersWithIV(key, ivData);

        SICBlockCipher aesCTR = new SICBlockCipher(new AESFastEngine());

        aesCTR.init(true, iv);
        byte[] plaintext = in.getBytes("UTF-8");
        byte[] ciphertext = new byte[ivData.length + plaintext.length];
        System.arraycopy(ivData, 0, ciphertext, 0, IV_SIZE);
        aesCTR.processBytes(plaintext, 0, plaintext.length, ciphertext, IV_SIZE);
        return ciphertext;
    }

    private static String decryptWithAES_CTR(KeyParameter key, byte[] ciphertext)
            throws IllegalArgumentException, UnsupportedEncodingException,
            DataLengthException {
        if (ciphertext.length < IV_SIZE) {
            throw new IllegalArgumentException("Ciphertext too short to contain IV");
        }

        ParametersWithIV iv = new ParametersWithIV(key, ciphertext, 0, IV_SIZE);

        SICBlockCipher aesCTR = new SICBlockCipher(new AESFastEngine());
        aesCTR.init(true, iv);
        byte[] plaintext = new byte[ciphertext.length - IV_SIZE];
        aesCTR.processBytes(ciphertext, IV_SIZE, plaintext.length, plaintext, 0);
        return new String(plaintext, "UTF-8");
    }
}

计数器模式不需要填充，并且完全在线，因此您只需要调用 processBytes 。对于CBC模式，您应该查看 PaddedBufferedBlockCipher 。在解密过程中，您仍然会有少量的缓冲区处理：在解密之前，您不知道填充的数量。

Counter mode does not require padding and is fully online, so you only have to call processBytes. For CBC mode you should look at PaddedBufferedBlockCipher. Still you would have slightly a tiny amount of buffer handling during decryption: before decryption you don't know the amount of padding that is present.

您可以删除IV代码和UTF-8字符解码+异常处理，但您可能会感到不安全，甚至可能不兼容。此代码将IV前缀为密文。

You could remove the IV code and the UTF-8 character decoding + exception handling, but you would be insecure and possibly incompatible. This code prefixes the IV to the ciphertext.

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