Dealing with Context in WSFederation and ACS

gistfile1.cs

 [AllowAnonymous]
    [ValidateInput(false)]
    public class AcsResponseController : Controller
    {
        public ActionResult Index()
        {
            if (ControllerContext.HttpContext.Request.Form["wresult"] != null)
            {
                // This is a response from the ACS - you can further inspect the message if you will
                SignInResponseMessage message =
                    WSFederationMessage.CreateFromNameValueCollection(
                    WSFederationMessage.GetBaseUrl(ControllerContext.HttpContext.Request.Url),
                    ControllerContext.HttpContext.Request.Form)
                    as SignInResponseMessage;

                if (!string.IsNullOrWhiteSpace(message.Context))
                {
                    // create Saml2SecurityToken (if we know it is SAML2)
                    Saml2SecurityToken 
                        token = FederatedAuthentication
                        .WSFederationAuthenticationModule.GetSecurityToken(message)
                        as Saml2SecurityToken;

                    // user the message.Context on our own will
                Response.Redirect("~/");
            }
            else
            {
                Response.Redirect("~/");
            }
            return Redirect("~/");
        }
    }