在Android中加密和解密zip文件？

Question

我使用这种代码：http://examples.javacodegeeks.com/core-java/crypto/encrypt-decrypt-file-stream-with-des加密我的zip文件在Android应用程序中使用。它使用zip文件工作得很好，当我尝试使用java代码时，但是当我在Android应用程序中尝试相同的方法 - 它解密文件但我得到的文件已损坏，无法打开它。

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  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) 

当我尝试打开W​​indows上的同一个文件使用WinZip它显示：

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()); 
    } 

} 

} 

这是类我正在使用：

Answer 1

的问题是，你使用不同的密钥来加密和解密文件：

1）你叫从某处encrypt(..)的EncryptDecryptFileStreamWithDES，这反过来调用您call()方法，它初始化新的密钥外：

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

2）然后您拨打decrypt(..)，再次调用您的call()方法，您将获得新的SecretKey。

在您使用的示例中没有这样的问题，这些方法调用存在相反的顺序。 为了扩展这个例子中，你需要持有的encrypt(..)和decrypt(..)调用之间的键，然后与存储的关键初始化SecretKeySpec：

byte[] keyBytes = KeyGenerator.getInstance("AES").getEncoded(); 

... 

SecretKeySpec skeySpec = new SecretKeySpec(keyBytes, "AES"); 
Cipher cipher = Cipher.getInstance("AES"); 
cipher.init(Cipher.DECRYPT_MODE, skeySpec); 

Here是多一点点真实的例子。

P.S.如前所述，使用DES算法不是最好的主意，请使用AES代替。