private function getEncParams()
    {
        // Parametri obbligatori
        $params = array(
            'shopLogin' => $this->getShopLogin(),
            'uicCode' => $this->getCurrency(),
            'amount' => $this->getAmount(),
            'shopTransactionId' => $this->getShopTransactionID(),
        );

        return array_merge($params, $this->getOptParams());
    }