Question

我使用 DES 算法来加密/解密我的文本。它与拉丁文本完美配合。

但是当我开始加密/解密西里尔文本时，解密的文本显示为 ?????我的TextField表单和控制台中的。我该如何解决？

在Joachim Sauer advice之后我将inputBytes = textToEnrypt.getBytes();更改为inputBytes = textToEnrypt.getBytes("UTF-8");，现在我已经 javax.crypto.IllegalBlockSizeException 了。请帮帮我......

package crypting;

import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
import javax.microedition.midlet.*;

public class Encryptor extends MIDlet {

    String buffer;

    public void startApp() {
        String keyString = "testtest";
//        encrypt("Text for encrypting", keyString);
        encrypt("Привет", keyString);
        decrypt(buffer, keyString);
    }

    public void pauseApp() {
    }

    public void destroyApp(boolean unconditional) {
    }

    public void encrypt(String textToEnrypt, String keyString) {
        Cipher cipher;
        try {
            cipher = Cipher.getInstance("DES");
        } catch (Exception ex) {
            System.out.println(ex.toString());
            return;
        }

        byte[] keyData = keyString.getBytes();
        SecretKeySpec key = new SecretKeySpec(keyData, 0, keyData.length, "DES");

        try {
            cipher.init(Cipher.ENCRYPT_MODE, key);
        } catch (Exception ex) {
            System.out.println(ex.toString());
            return;
        }

        int cypheredBytes = 0;

        byte[] inputBytes;
        try {
            inputBytes = textToEnrypt.getBytes("UTF-8");
//            inputBytes = textToEnrypt.getBytes();
        } catch (Exception ex) {
            System.out.println(ex.toString());
            return;
        }

        byte[] outputBytes = new byte[100];

        try {
            cypheredBytes = cipher.doFinal(inputBytes, 0, inputBytes.length,
                    outputBytes, 0);
        } catch (Exception ex) {
            System.out.println(ex.toString());
            return;
        }

        String str = new String(outputBytes, 0, cypheredBytes);
        buffer = str;
        System.out.println("Encrypted string = " + str);
    }


    public void decrypt(String textToDecrypt, String keyString) {
        Cipher cipher;
        try {
            cipher = Cipher.getInstance("DES");
        } catch (Exception ex) {
            System.out.println(ex.toString());
            return;
        }

        byte[] keyData = keyString.getBytes();
        SecretKeySpec key = new SecretKeySpec(keyData, 0, keyData.length, "DES");

        try {
            cipher.init(Cipher.DECRYPT_MODE, key);
        } catch (Exception ex) {
            System.out.println("2. " + ex.toString());
            return;
        }

        int cypheredBytes = 0;

        byte[] inputBytes;
        try {
            inputBytes = textToDecrypt.getBytes("UTF-8");
//            inputBytes = textToDecrypt.getBytes();
        } catch (Exception ex) {
            System.out.println("3. " + ex.toString());
            return;
        }

        byte[] outputBytes = new byte[100];

        try {
            cypheredBytes = cipher.doFinal(inputBytes, 0, inputBytes.length,
                    outputBytes, 0);
        } catch (Exception ex) {
            System.out.println("4. " + ex.toString());
            return;
        }

        String str = new String(outputBytes, 0, cypheredBytes);
        System.out.println("Decrypted string = " + str);
    }
}

Answer 1

我的猜测（如果没有显示某些代码，我就无法做得更多）就是你在没有参数的情况下使用getBytes()并在没有参数的情况下从String构建byte[]参数也是如此。这意味着使用平台默认编码，如果不能代表西里尔字符，那就是你得到的。

最好将UTF-8用于两种转换，这样就可以表示每个Unicode字符。

Answer 2

DES使用64位（8字节）块大小。你必须确保你正在加密的数据是8个字节的倍数，即用零字节或其他任何东西填充它以确保它是。否则你会得到一个IllegalBlockSizeException。在将字符串转换为UTF-8之后，您需要执行此操作，当然......

Answer 3

我能够使其与以下更改一起使用。

将加密方法的返回类型从void更改为byte[]：

static public byte[] encrypt(String textToEnrypt, String keyString)
  throws Exception
{
    //at the end
    //write this down:
    byte[] newResponse = new byte[cypheredBytes];
    for(int i=0;i &lt; cypheredBytes;i++)
    {
        newResponse[i] = outputBytes[i];
    }
    return newResponse;
}

而不是：

String str = new String(outputBytes, 0, cypheredBytes);
buffer = str;
System.out.println("Encrypted string = " + str);

Answer 4

一个问题是行

String str = new String(outputBytes, 0, cypheredBytes);

加密方法中的

。您不能将String用作二进制数据的容器。除非是加密数据，否则不应将加密数据转换为字符串，然后需要使用适当的编解码器，例如base64。

J2ME文本加密 - javax.crypto.IllegalBlockSizeException

4 个答案: