Encrypting and decrypting a zip file in Android?

Question

I am using this code: http://examples.javacodegeeks.com/core-java/crypto/encrypt-decrypt-file-stream-with-des for encrypting my zip files used in android app .It is working really fine with the zip files when I tried it using java code ,But when I tried same methods in Android app - It decrypts the file but file I get is corrupted and unable to open it.

Log:

         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) 

And when I try to open the same file on Windows with winzip it displays:

   Does not appear to be a valid archive file.

Update::

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());
    }

}

}

This is the Class which I am using:

Answer 1

The problem is that you use different keys to encrypt and decrypt the file:

1) You call encrypt(..) from somewhere outside the EncryptDecryptFileStreamWithDES, which in its turn calls your call() method, which initializes new key:

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

2) Then you call decrypt(..), which calls your call() method again and you get new SecretKey.

There is no such a problem in the example you used, there is an opposite order of these methods invocations. To extend this example you need to hold the key between invocation of encrypt(..) and decrypt(..) and then initialize SecretKeySpec with the key stored:

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

...

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

Here is a little bit more real-life example.

P.S. As it was mentioned, using DES algorithm is not the best idea, use AES instead.