public string Downloading(string url)
    {
      X509Store store = new X509Store("MY", StoreLocation.CurrentUser);
      store.Open(OpenFlags.ReadOnly | OpenFlags.OpenExistingOnly);
      
      
      X509Certificate2Collection scollection = (X509Certificate2Collection)store.Certificates.Find(X509FindType.FindByTimeValid, DateTime.Now, false);
      
      X509Certificate2Collection ui = X509Certificate2UI.SelectFromCollection(scollection, "Выберите сертификат", "Сертификаты:", X509SelectionFlag.SingleSelection);
      X509Certificate2 x509 = (X509Certificate2)ui[0];
      
      try
      {
        Console.WriteLine(x509.PrivateKey.ToString());
      }
      catch (Exception e)
      {
        Console.WriteLine(e.Message); //Алгоритм ключа не поддерживается 
      }
      
      HttpWebRequest request_authorize = (HttpWebRequest)WebRequest.Create(url);
      request_authorize.UserAgent = "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR 1.1.4322; .NET CLR 2.0.50727)";
      request_authorize.AllowAutoRedirect = true;
      request_authorize.Referer = this.url;
      request_authorize.Timeout = 60000 * 25; //25 минут
      
      ServicePointManager.ServerCertificateValidationCallback = (a, b, c, d) => true;
      request_authorize.ClientCertificates.Add(x509);


    

        HttpWebResponse response_authorize = (HttpWebResponse)request_authorize.GetResponse();
        string html = new StreamReader(response_authorize.GetResponseStream(), Encoding.UTF8).ReadToEnd();
        return html;
     
      
      
      

    }