PHP and JAVA Encryption And Decryption Routines

Question

I have the following PHP routine to encrypt my communication with the client:

public static function encrypt($input, $key) {
        $size = mcrypt_get_block_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_ECB); 
        $input = AES::pkcs5_pad($input, $size); 
        $td = mcrypt_module_open(MCRYPT_RIJNDAEL_128, '', MCRYPT_MODE_ECB, ''); 
        $iv = mcrypt_create_iv (mcrypt_enc_get_iv_size($td), MCRYPT_RAND); 
        mcrypt_generic_init($td, $key, $iv); 
        $data = mcrypt_generic($td, $input); 
        mcrypt_generic_deinit($td); 
        mcrypt_module_close($td); 
        $data = base64_encode($data); 
        return $data; 
}

and the following Java rotuine to decrypt my communication with the server:

public static String decrypt(String input, String key) {
        byte[] output = null;
        try {
            SecretKeySpec skey = new SecretKeySpec(key.getBytes(), "AES");
            Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
            cipher.init(Cipher.DECRYPT_MODE, skey);
            output = cipher.doFinal(Base64.decode(input,Base64.NO_WRAP));
        } catch (Exception e) {
            System.out.println(e.toString());
        }
        return new String(output);
}

Why does the following decryption routine throws an exception?

java.lang.IllegalArgumentException: bad base-64

Edit: After hardcoding the string into the code I am getting a BadPaddingException.

my input to decrypt function :

wrmRa2hAoseNOev6/ascapxkLQRGX/GW3DQm3ETwBH7gJm1NetkgGFzgY4kZTE10Tv45YIcy/xoodq/GumSY5hsao1s4bkuKXZeim/IDTVr3elrqX13b81/XE5iB3iJrAqny2dQ5SsWso0lUcAZGS2Wls/lTeQiIKXEaOh7iZZ3xOtM6633iNcoiFxEnX5A0dMrdRNEOkmQ3UnQmuIGTSv0RLKuPv5r5dplGZ3N2LMMpoB0AMu3DSXFEdiD4XN49

@USKMobility, tried using URL_SAFE alone and it didn't work, trying the answer that was suggested now. — NotGI
– NotGI, Commented Oct 1, 2016 at 10:28
try to observe your input string that have non-base64 character — Umesh Singh Kushwaha
– Umesh Singh Kushwaha, Commented Oct 1, 2016 at 10:30
@USKMobility my input string is directly from the PHP function, is it possible it will generate non Base64 chars? — NotGI
– NotGI, Commented Oct 1, 2016 at 10:31
It is best not to use mcrypt, it is abandonware, has not been updated in years and 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 had many outstanding bugs dating back to 2003. Instead consider using defuse or RNCryptor, they provide a complete solution and are being maintained and is correct. — zaph
– zaph, Commented Oct 1, 2016 at 11:10

Tigger · Accepted Answer · 2016-10-01 10:05:14Z

1

It is possible that you need to use:

Base64.decode(input,Base64.NO_WRAP|Base64.URL_SAFE)

It is also possible you need a different combo of flags too.

It also depends how you are getting the base64 string. Sometimes the '+' is converted to a ' ' (space) if it transferred from a URL or other online source.

answered Oct 1, 2016 at 10:05

Tigger

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6 Comments

NotGI Over a year ago

I still get bad-base64, the string I'm encrypting on the php script is constant it's a string containing javascript that doesn't change.

Tigger Over a year ago

Without seeing the base64 string or knowing exactly how you are transferring the base64 string I can only guess. I'm guessing this might not be something you want to share, but maybe you can do a test case that also produces the error and you can share.

NotGI Over a year ago

I get the usual base64 string with no bad chars, it doesn't make sense.

Tigger Over a year ago

It makes sense to me - it all depends on the transfer method. Just for fun / debug, you could do a test by hard-coding the base64 string in to your Java to see if that works. The Wikipedia article might help too.

NotGI Over a year ago

I hardcoded as you suggested and now I'm getting a BadPaddingException, also added the base64 string to thread and using your Base64.NO_WRAP | Base64.URL_SAFE causes a bad-base64 exception, any ideas?

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