SagePay (VPSProtocol 3.00) AES/CBC/PCKS#5 encryption problems

Question

I am trying to initiate an order on the Sage Pay servers using VPSProtocol 3.00. I am having problems encrypting the NVP data to generate the "Crypt" field.

When I submit the details to the Sage Pay servers it says "3045 : The Currency field is missing.".

I know my encrypted NVPs are all correct including the currency field. If I change the encryption key to something wrong I get the same error which leads me to believe it's an encryption problem.

Here's the code I am using...

class sagepay{

    /**
     * My Encryption Key
     */
    const encryptionKey = 'MY-ENCRYPTION-KEY';

    /**
     * Encryption Function.
     * @param string $data NVP Data to be encrypted.
     * @return string Encrypted Data.
     */
    public static function doEncrypt($data){
        $strCrypt = mcrypt_encrypt(MCRYPT_RIJNDAEL_128, self::encryptionKey, self::_pkcs5_pad($data), MCRYPT_MODE_CBC, self::encryptionKey);
        return "@".bin2hex($strCrypt);
    }

    /**
     * Pad Data
     * @param string $text NVP Data being encrypted.
     * @return string Padded Data.
     */
    private static function _pkcs5_pad($text){
        $blocksize = mcrypt_get_block_size('des', 'cbc');
        $pad = $blocksize - (strlen($text) % $blocksize);
        return $text . str_repeat(chr($pad), $pad);
    }
}

Thanks.

Answer 1

Richard,

This issue is generally due to a bad Encryption key, please triple check that.

Regards,

Pablo

Answer 2

Just check my class to find the working php sagepay form protocol v3 version https://github.com/acidrat/sagepayForm-php