Different AES128 with zero padding encryption result between php and java

Question

I have a different result between java and php method in doing AES128 with zero padding and no IV encryption.

Here PHP code :

<?php
$ptaDataString = "secretdata";
$ptaDataString = encryptData($ptaDataString);
$ptaDataString = base64_encode($ptaDataString);
function encryptData($input) {
                $ptaKey = 'secret'; 
                $iv = "\0";
                $encrypted = mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $ptaKey, $input, MCRYPT_MODE_CBC, $iv);
                return $encrypted;
}
echo $ptaDataString;
?>

And here is java code:

public static String encrypt() throws Exception {
    try {
        String data = "secretdata";
        String key = "secret0000000000";
        String iv = "0000000000000000";

        Cipher cipher = Cipher.getInstance("AES/CBC/NoPadding");
        int blockSize = cipher.getBlockSize();

        byte[] dataBytes = data.getBytes();
        int plaintextLength = dataBytes.length;
        if (plaintextLength % blockSize != 0) {
            plaintextLength = plaintextLength + (blockSize - (plaintextLength % blockSize));
        }

        byte[] plaintext = new byte[plaintextLength];
        System.arraycopy(dataBytes, 0, plaintext, 0, dataBytes.length);

        SecretKeySpec keyspec = new SecretKeySpec(key.getBytes(), "AES");
        IvParameterSpec ivspec = new IvParameterSpec(iv.getBytes());

        cipher.init(Cipher.ENCRYPT_MODE, keyspec, ivspec);
        byte[] encrypted = cipher.doFinal(plaintext);

        return new sun.misc.BASE64Encoder().encode(encrypted);

    } catch (Exception e) {
        e.printStackTrace();
        return null;
    }
}

php resulting : kjgE5p/3qrum6ghdjiVIoA==

Java resulting : zLKhVMksRRr1VHQigmPQ2Q==

Any help would be appreciated, Thanks

It is best not to use mcrypt, it has been abandonware for nearly a decade now. It has therefore been deprecated and will be removed from the core and into PECL in PHP 7.2. It does not support standard PKCS#7 (née PKCS#5) padding, only non-standard null padding that can't even be used with binary data. mcrypt has many outstanding bugs dating back to 2003. Instead consider using defuse or RNCryptor, they provide a complete solution, are being maintained and is correct. — zaph
– zaph, Commented Jan 25, 2017 at 16:31

Duncan Jones · Accepted Answer · 2014-10-09 06:41:09Z

3

In Java, a zero byte expressed as a string is "\0" not "0". If you correct your example as follows, the results match:

String data = "secretdata";
String key = "secret\0\0\0\0\0\0\0\0\0\0";
String iv = "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0";

In the case of the IV, it's probably just easier to write:

byte[] iv = new byte[<block size>];

In the final line of your code, you access sun.misc.BASE64Encoder(). Accessing anything that starts with sun.* is frowned upon, since these are internal classes. Consider instead using:

return DatatypeConverter.printBase64Binary(encrypted);

answered Oct 9, 2014 at 6:41

Duncan Jones

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