TLS 1.1

protected void CreateAuthorization()
        {
            //Remember these for later.
            System.Net.ServicePointManager.SecurityProtocol = System.Net.SecurityProtocolType.Tls11;
            HttpContext.Current.Session["consumerKey"] = consumerKey;
            HttpContext.Current.Session["consumerSecret"] = consumerSecret;
            HttpContext.Current.Session["oauthLink"] = OAUTH_URL;
            //
            IOAuthSession session = CreateSession();
            IToken requestToken = session.GetRequestToken();
            HttpContext.Current.Session["requestToken"] = requestToken;
            
            tokenSecret = requestToken.TokenSecret;
            var authUrl = string.Format("{0}?oauth_token={1}&oauth_callback={2}", AUTHORIZE_URL, requestToken.Token, UriUtility.UrlEncode(oauth_callback_url));
            HttpContext.Current.Session["oauthLink"] = authUrl;
            Response.Redirect(authUrl);
        }