Java Cipher 解密中的奇怪字符

Question

我的程序有一个奇怪的问题，我想加密一些字符串然后解密它们；我做了一个试用类来测试加密和解密的功能。加密工作正常，但是当我尝试解密时，只有有时，我在字符串中间有奇怪的字符。 这是我的代码：

public class Prova {

public static void main(String[] args){
    String s = "with the lights out is less dangerous here we are now entertain us";
    s = cripta(s);
    System.out.println(s);
    s = decripta(s);
    System.out.println(s);
}

public static String cripta(String s){
    System.out.println("lunghezza stringa:"+s.length());
    byte[] input = s.getBytes();
    byte[] output;
    byte[] keyBytes = hexStringToByteArray("AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA");
    byte[] ivBytes = hexStringToByteArray("AAAAAAAAAAAAAAAA");
    String out = "";


    SecretKeySpec key = new SecretKeySpec(keyBytes, "DESede" );
    IvParameterSpec ivSpec = new IvParameterSpec(ivBytes);
    try {
        Cipher cp = Cipher.getInstance("DESede/ECB/PKCS5Padding");
        cp.init(Cipher.ENCRYPT_MODE, key);
        byte[] criptati = new byte[cp.getOutputSize(input.length)];
        int enc_len = cp.update(input, 0, input.length, criptati, 0);
        enc_len += cp.doFinal(criptati, enc_len);
        out = new String(criptati);
    } catch (NoSuchAlgorithmException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (NoSuchPaddingException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (InvalidKeyException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (ShortBufferException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IllegalBlockSizeException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (BadPaddingException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    return out;
}

public static String decripta(String s){

    byte[] input = s.getBytes();
    byte[] output;
    byte[] keyBytes = hexStringToByteArray("AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA");
    byte[] ivBytes = hexStringToByteArray("AAAAAAAAAAAAAAAA");
    String out = "";

    try {
        SecretKeySpec key = new SecretKeySpec(keyBytes, "DESede");
        IvParameterSpec ivSpec = new IvParameterSpec(ivBytes);
        Cipher cp = Cipher.getInstance("DESede/ECB/NoPadding");
        cp.init(Cipher.DECRYPT_MODE,  key);
        byte[] decrypt = new byte[cp.getOutputSize(input.length)];

        int dec_len = cp.update(input, 0, input.length, decrypt, 0);
        System.out.println(dec_len);
        dec_len += cp.doFinal(decrypt, dec_len );
        System.out.println(dec_len);
        out = new String(decrypt);
    } catch (NoSuchAlgorithmException | NoSuchPaddingException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (InvalidKeyException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (ShortBufferException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IllegalBlockSizeException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (BadPaddingException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    return out;
}

private static byte[] hexStringToByteArray(String s) {
    // TODO Auto-generated method stub
    int len = s.length();
    byte[] data = new byte[len / 2];
    for (int i = 0; i < len; i += 2) {
        data[i / 2] = (byte) ((Character.digit(s.charAt(i), 16) << 4)
                             + Character.digit(s.charAt(i+1), 16));
    }
    return data;

}

}

我收到的输出是“熄灯后的 dangÝâ¥8,–xÖÆZŽÏö=æe 现在招待我们”

Answer 1

问题是加密字节可能包含一些值，这些值在简单地转换为字符串时会导致奇怪的行为。所以你应该像这样使用base64编码：

在密码中：

out = new String(Base64.getEncoder().encode(criptati));

简述：

byte[] input = Base64.getDecoder().decode(s.getBytes());

顺便问一下：你为什么用cp.update()？为什么不只是 cp.doFinal() 那样：

Cipher cp = Cipher.getInstance("DESede/ECB/PKCS5Padding");
cp.init(Cipher.ENCRYPT_MODE, key);
byte[] criptati = cp.doFinal(input);
out = new String(Base64.getEncoder().encode(criptati));

decript 也一样？

编辑

删除所有杂乱（TODO-cmets、未使用的代码等）的工作示例：

public static void main(String[] args) {
        String s = "with the lights out is less dangerous here we are now entertain us";
        s = cripta(s);
        System.out.println(s);
        s = decripta(s);
        System.out.println(s);
    }

    public static String cripta(String s) {
        System.out.println("lunghezza stringa:" + s.length());
        byte[] input = s.getBytes();
        byte[] keyBytes = hexStringToByteArray("AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA");
        String out = "";

        SecretKeySpec key = new SecretKeySpec(keyBytes, "DESede");
        try {
            Cipher cp = Cipher.getInstance("DESede/ECB/PKCS5Padding");
            cp.init(Cipher.ENCRYPT_MODE, key);
            byte[] criptati = cp.doFinal(input);
            out = new String(Base64.getEncoder().encode(criptati));
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (NoSuchPaddingException e) {
            e.printStackTrace();
        } catch (InvalidKeyException e) {
            e.printStackTrace();
        } catch (IllegalBlockSizeException e) {
            e.printStackTrace();
        } catch (BadPaddingException e) {
            e.printStackTrace();
        }

        return out;
    }

    public static String decripta(String s) {

        byte[] input = Base64.getDecoder().decode(s.getBytes());
        byte[] keyBytes = hexStringToByteArray("AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA");
        String out = "";

        try {
            SecretKeySpec key = new SecretKeySpec(keyBytes, "DESede");
            Cipher cp = Cipher.getInstance("DESede/ECB/NoPadding");
            cp.init(Cipher.DECRYPT_MODE, key);
            byte[] decrypt = cp.doFinal(input);
            out = new String(decrypt);
        } catch (NoSuchAlgorithmException | NoSuchPaddingException e) {
            e.printStackTrace();
        } catch (InvalidKeyException e) {
            e.printStackTrace();
        } catch (IllegalBlockSizeException e) {
            e.printStackTrace();
        } catch (BadPaddingException e) {
            e.printStackTrace();
        }
        return out;
    }