Question

I have a problem I have been trying to solve for last three days. I have to use DES to encrypt an array of bytes to get a specific result. The default implementation of DES in Java (Javax.crypto.cipher, JDK 7, provider SunJCE version 1.7), however, seemingly does not work.
When I have the following code:

    private void testDES() throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
        Cipher cipher = Cipher.getInstance("DES/ECB/NoPadding");
        byte[] keyByte = convertStringToBytes("00 00 00 00 00 00 00 00");
        byte[] data = convertStringToBytes("00 00 00 00 00 00 00 00");
        Key key = new SecretKeySpec(keyByte, "DES");
        cipher.init(Cipher.ENCRYPT_MODE, key);
        System.out.println(hexadecimalString(cipher.doFinal(data)));
    }

It prints F4 DA 4D 97 BF CF 23 D9 instead of the correct result 8C A6 4D E9 C1 B1 23 A7 (according to the test vectors : http://common-lisp.net/project/clbuild/mirror/ironclad/test-vectors/des.testvec)
The methods hexadecimalString and convertStringToBytes just transform byte to hexa and vice versa.
Could anyone please help me? After searching for a rather long time, I just don’t know what to do. Thanks in advance. Joe

Answer 1

I think the problem is with either convertStringToBytes or hexadecimalString.

You can replace:

byte[] keyByte = convertStringToBytes("00 00 00 00 00 00 00 00");
byte[] data = convertStringToBytes("00 00 00 00 00 00 00 00");

with:

byte[] keyByte = new byte[8];
byte[] data = new byte[8];

… because in Java, arrays are initialised to zero.

When I run the same code, but with the above (and not convertStringToBytes), then I get the expected result (8C A6 …)

Edit:
Since you’re still having problems, here’s a full program. The output for me is:

8c a6 4d e9 c1 b1 23 a7 

Code below:

public class Main {
    public static void main(String[] args) throws GeneralSecurityException {
        Cipher cipher = Cipher.getInstance("DES/ECB/NoPadding");
        byte[] keyByte = new byte[8];
        byte[] data = new byte[8];
        Key key = new SecretKeySpec(keyByte, "DES");
        cipher.init(Cipher.ENCRYPT_MODE, key);
        byte[] result = cipher.doFinal(data);
        StringBuilder str = new StringBuilder();
        for (byte b : result) {
             str.append(Integer.toHexString(0xff & b)).append(' ');
        }
        System.out.println(str);
    }
}