Omnipay\Alipay\Requests\AbstractAopRequest::sign PHP Метод

    protected function sign($params, $signType)
    {
        $signer = new Signer($params);
        $signer->setIgnores(['sign']);
        $signType = strtoupper($signType);
        if ($signType == 'RSA') {
            $sign = $signer->signWithRSA($this->getPrivateKey());
        } elseif ($signType == 'RSA2') {
            $sign = $signer->signWithRSA($this->getPrivateKey(), OPENSSL_ALGO_SHA256);
        } else {
            throw new InvalidRequestException('The signType is invalid');
        }
        return $sign;
    }