public function createResponseHash($amount, $dateTime, $code)
    {
        $this->validate('storeId', 'sharedSecret', 'currency');

        $storeId      = $this->getStoreId();
        $sharedSecret = $this->getSharedSecret();
        $currency     = $this->getCurrencyNumeric();

        $stringToHash = $sharedSecret . $code . $amount . $currency . $dateTime . $storeId;
        $ascii        = bin2hex($stringToHash);

        return sha1($ascii);
    }