C#中实现https的双向认证

问题：

【SSL】WebClient 请求 https 页面出错:未能创建 SSL/TLS 安全通道

代码：

 /**
        post 表单的方式发送请求数据
        **/
        public String sendMessage(String postUrl, NameValueCollection postData)
        {
            ServicePointManager.ServerCertificateValidationCallback = new System.Net.Security.RemoteCertificateValidationCallback(CheckValidationResult);

            //WebClient web = new WebClient();
            //byte[] respData = web.UploadValues(postUrl, "POST", postData);
            //String resp = Encoding.UTF8.GetString(respData);

            String resp;
            using (SecureWebClient client = new SecureWebClient())
            {
                byte[] respData = client.UploadValues(postUrl, "POST", postData);
                resp = Encoding.UTF8.GetString(respData);
            }
            return resp;
        }

        /// <summary>
        /// 总是接受 认证平台 服务器的证书
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="certificate"></param>
        /// <param name="chain"></param>
        /// <param name="errors"></param>
        /// <returns></returns>
        public static bool CheckValidationResult(object sender, System.Security.Cryptography.X509Certificates.X509Certificate certificate, System.Security.Cryptography.X509Certificates.X509Chain chain, System.Net.Security.SslPolicyErrors errors)
        {   // 总是接受 认证平台 服务器的证书
            return true;
        }

        /// <summary>
        /// https双向认证
        /// </summary>
        public class SecureWebClient : WebClient
        {
            /// <summary>
            /// 加载证书
            /// </summary>
            /// <param name="address"></param>
            /// <returns></returns>
            protected override WebRequest GetWebRequest(Uri address)
            {
                HttpWebRequest request = (HttpWebRequest)base.GetWebRequest(address);
                var cer = new X509Certificate2(Config.GetValue("MinSheng_custPriPfxPath"), Config.GetValue("MinSheng_custPriPfxPwd"));
                request.ClientCertificates.Add(cer);
                return request;
            }
        }

注：

当调用 X509Certificate2 的时候，会提示找不到文件而报错。

发现文件也是存在的，就是这个函数读取不了，网上查了一下，发现是IIS的程序池配置问题，云服务器上的自动加载配置文件设为Fasle的，只要在你网站的程序池中，设置为True就解决了。