Java 3DES 实现（学术）

Question

到目前为止我的代码是：

public class TripleDES {
    /**
     * @param args the command line arguments
     * @throws java.security.NoSuchAlgorithmException
     * @throws javax.crypto.NoSuchPaddingException
     * @throws java.security.InvalidKeyException
     * @throws javax.crypto.IllegalBlockSizeException
     * @throws javax.crypto.BadPaddingException
     */
    public static void main(String[] args) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
        //Encrypt: C = EK3(DK2(EK1(P)))
        //Decrypt: P = DK3(EK2(DK1(C)))
        
        Scanner sc = new Scanner(System.in);
        
        //Generate key for DES
        KeyGenerator keyGenerator = KeyGenerator.getInstance("DES");
        SecretKey secretKey = keyGenerator.generateKey();
        SecretKey secretKey2 = keyGenerator.generateKey();
        SecretKey secretKey3 = keyGenerator.generateKey();
        
        //Text Enc & Dec
        Cipher cipher = Cipher.getInstance("DES/ECB/PKCS5Padding");



        
        //enter msg
        System.out.print("Enter a string: ");
        String x= sc.nextLine();
        
//enc
        cipher.init(Cipher.ENCRYPT_MODE,secretKey);
        byte[] message = x.getBytes();//text
        byte[] messageEnc = cipher.doFinal(message);//encryption with key1
        cipher.init(Cipher.DECRYPT_MODE,secretKey2);
        byte[] deck2 = cipher.doFinal(messageEnc);//decryption with key2
        cipher.init(Cipher.ENCRYPT_MODE,secretKey3);
        byte[] messageEnc1 = cipher.doFinal(deck2);//encryption with key3
        System.out.println("Cipher Text: " + new String(messageEnc1));
        
        //dec
        cipher.init(Cipher.DECRYPT_MODE,secretKey3);
        byte[] dec = cipher.doFinal(messageEnc1);//decryption with key1
        cipher.init(Cipher.ENCRYPT_MODE,secretKey2);
        byte[] messageEnc2 = cipher.doFinal(dec);//encryption with key2
        cipher.init(Cipher.DECRYPT_MODE,secretKey);
        byte[] deck3 = cipher.doFinal(messageEnc2);//decryption with key3
        System.out.println("Plain Text: " + new String(deck3));
    }
}

我收到错误：

Exception in thread "main" javax.crypto.BadPaddingException: Given final block not properly padded. Such issues can arise if a bad key is used during decryption.
    at com.sun.crypto.provider.CipherCore.doFinal(CipherCore.java:991)
    at com.sun.crypto.provider.CipherCore.doFinal(CipherCore.java:847)
    at com.sun.crypto.provider.DESCipher.engineDoFinal(DESCipher.java:314)
    at javax.crypto.Cipher.doFinal(Cipher.java:2164)
    at tripledes.TripleDES.main(TripleDES.java:45)

我的猜测是，当我在第 45 行尝试使用不同的密钥解密时出现上述错误，这是因为加密文本比生成的密钥大，但我不太确定。

谁能帮我解决问题，我想不通。

Answer 1

我指的是最初发布的带有 cipher、cipher2 和 cipher3 实例的代码：问题是关于 cipher2 和 [=12= 的填充].只有cipher可以使用PKCS5Padding，cipher2和cipher3必须申请NoPadding。

如果 secretKey、secretKey2 和 secretKey3 的串联字节用作 3DES 密钥，则生成的密文确实与 3DES 生成的密文相同.

ECB是一个不安全的模式，顺便说一句，s。 here.

关于评论：
对于使用字符集编码的密文解码，请参见例如Problems when converting from byte array to string and back to byte array. Concerning the missing encoding specification, s. e.g. String.getBytes() in different default charsets.

Java 3DES 实现（学术）

Java 3DES implementation (academic)

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encryption

3des

cryptography

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