Omnipay\Alipay\Common\Signer::signContentWithRSA PHP Метод

    public function signContentWithRSA($content, $privateKey, $alg = OPENSSL_ALGO_SHA1)
    {
        $privateKey = $this->prefix($privateKey);
        $privateKey = $this->format($privateKey, self::KEY_TYPE_PRIVATE);
        $res = openssl_pkey_get_private($privateKey);
        $sign = null;
        try {
            openssl_sign($content, $sign, $res, $alg);
        } catch (Exception $e) {
            if ($e->getCode() == 2) {
                $message = $e->getMessage();
                $message .= "\n应用私钥格式有误，见 https://github.com/lokielse/omnipay-alipay/wiki/FAQs";
                throw new Exception($message, $e->getCode(), $e);
            }
        }
        openssl_free_key($res);
        $sign = base64_encode($sign);
        return $sign;
    }