Question

我正在使用此代码：http://examples.javacodegeeks.com/core-java/crypto/encrypt-decrypt-file-stream-with-des用于加密我在Android应用程序中使用的zip文件。当我使用java代码尝试使用zip文件时它工作得很好但是当我在Android应用程序中尝试相同的方法时 - 它解密文件，但我收到的文件已损坏，无法打开。

日志：

         04-19 10:58:25.711: W/System.err(6752): net.lingala.zip4j.exception.ZipException: zip headers not found. probably not a zip file
         04-19 10:58:25.721: W/System.err(6752):    at net.lingala.zip4j.core.HeaderReader.readEndOfCentralDirectoryRecord(HeaderReader.java:122)

当我尝试使用winzip在Windows上打开相同的文件时，它会显示：

   Does not appear to be a valid archive file.

更新::

public class EncryptDecryptFileStreamWithDES {

private static Cipher ecipher;
private static Cipher dcipher;

// 8-byte initialization vector
private static byte[] iv = {
    (byte)0xB2, (byte)0x12, (byte)0xD5, (byte)0xB2,
    (byte)0x44, (byte)0x21, (byte)0xC3, (byte)0xC3
};

public static void call() {

    try {

        SecretKey key = KeyGenerator.getInstance("DES").generateKey();

        AlgorithmParameterSpec paramSpec = new IvParameterSpec(iv);

        ecipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
        dcipher = Cipher.getInstance("DES/CBC/PKCS5Padding");

        ecipher.init(Cipher.ENCRYPT_MODE, key, paramSpec);
        dcipher.init(Cipher.DECRYPT_MODE, key, paramSpec);

    //    encrypt(new FileInputStream("C:\\Users\\Admin\\Desktop\\zipped\\4.zip"), new FileOutputStream("C:\\Users\\Admin\\Desktop\\zipped\\4.dat"));
      //  decrypt(new FileInputStream("C:\\Users\\Admin\\Desktop\\zipped\\4.dat"), new FileOutputStream("C:\\Users\\Admin\\Desktop\\zipped\\4new.zip"));

    //}
    //catch (FileNotFoundException e) {
        //System.out.println("File Not Found:" + e.getMessage());
        //return;
    }
    catch (InvalidAlgorithmParameterException e) {
        System.out.println("Invalid Alogorithm Parameter:" + e.getMessage());
        return;
    }
    catch (NoSuchAlgorithmException e) {
        System.out.println("No Such Algorithm:" + e.getMessage());
        return;
    }
    catch (NoSuchPaddingException e) {
        System.out.println("No Such Padding:" + e.getMessage());
        return;
    }
    catch (InvalidKeyException e) {
        System.out.println("Invalid Key:" + e.getMessage());
        return;
    }

}

public static void encrypt(InputStream is, OutputStream os) {

    try {

        call();

        byte[] buf = new byte[1024];

        // bytes at this stream are first encoded
        os = new CipherOutputStream(os, ecipher);

        // read in the clear text and write to out to encrypt
        int numRead = 0;
        while ((numRead = is.read(buf)) >= 0) {
            os.write(buf, 0, numRead);
        }

        // close all streams
        os.close();

    }
    catch (IOException e) {
        System.out.println("I/O Error:" + e.getMessage());
    }

}

public static void decrypt(InputStream is, OutputStream os) {

    try {

        call();

        byte[] buf = new byte[1024];

        // bytes read from stream will be decrypted
        CipherInputStream cis = new CipherInputStream(is, dcipher);

        // read in the decrypted bytes and write the clear text to out
        int numRead = 0;
        while ((numRead = cis.read(buf)) > 0) {
            os.write(buf, 0, numRead);
        }

        // close all streams
        cis.close();
        is.close();
        os.close();

    }
    catch (IOException e) {
        System.out.println("I/O Error:" + e.getMessage());
    }

}

}

这是我正在使用的课程：

Answer 1

问题是您使用不同的密钥来加密和解密文件：

1）您从encrypt(..)之外的某个地方致电EncryptDecryptFileStreamWithDES，call()会调用您的SecretKey key = KeyGenerator.getInstance("DES").generateKey();方法，该方法会初始化新密钥：

decrypt(..)

2）然后，您拨打call()，再次调用SecretKey方法，然后获得新的encrypt(..)。

在您使用的示例中没有这样的问题，这些方法调用的顺序相反。要扩展此示例，您需要在调用decrypt(..)和SecretKeySpec之间按住键，然后使用存储的密钥初始化byte[] keyBytes = KeyGenerator.getInstance("AES").getEncoded(); ... SecretKeySpec skeySpec = new SecretKeySpec(keyBytes, "AES"); Cipher cipher = Cipher.getInstance("AES"); cipher.init(Cipher.DECRYPT_MODE, skeySpec);：

DES

Here是一个更现实的例子。

P.S。如上所述，使用AES算法不是最佳选择，请改用{{1}}。

在Android中加密和解密zip文件？

1 个答案: