SigningCredentials was not initialized

Question

I am creating a provider hosted app with my office 365 subscription. I created it as an asp.net MVC application and Modified the code according to this post

http://blogs.msdn.com/b/bspann/archive/2013/01/19/asp-net-mvc-based-apps-for-sharepoint-2013-on-premises.aspx

However I got this error in the token helper class, so I am clueless.

Update 1: WHen I initialize Visual Studio, and press F5 the first time in the app, VS asks me my office 365 credentials, however when debugging I see my account name on the Request object which is weird, I am thinking that could be the source of the issue but how to fix it?

Maybe my browser has that credential on memory:?

`

Update 2:
Code

[SharePointContextFilter]
public ActionResult Index()
{
    Uri hostWeb = new Uri(Request.QueryString["SPHostUrl"]);
    using(var clientContext=TokenHelper.GetS2SClientContextWithWindowsIdentity(hostWeb,Request.LogonUserIdentity))
    {
        var web= clientContext.Web;
        clientContext.Load(web, w=>w.Lists.Include(l=>l.Title).Where(l=> !l.Hidden));
        clientContext.ExecuteQuery();
        return View(web.Lists);
    }
}

Answer 1

Well, if you analyze the code for a second the name of the method is GetS2SClientContextWithWindowsIdentity, but I am creating a Sharepoint Online Provider Hosted App.

Does it make sense to get the client contex from a windows identity? obviously it does not.

After investigating for some minutes, I found there are other methods in the token helper class, and the one below makes more sense, doesnt it?

var contextToken = TokenHelper.GetContextTokenFromRequest(Request);
var hostWeb = Request.QueryString["SPHostUrl"];
using (var clientContext = TokenHelper.GetClientContextWithContextToken(hostWeb, contextToken, Request.Url.Authority))
{
  var web = clientContext.Web;
  clientContext.Load(web, w=>w.Lists.Include(l=>l.Title).Where(l=> !l.Hidden));
  clientContext.ExecuteQuery();
  return View(web.Lists);
​}
​ 

Posted also here on my blog for future reference: http://levalencia-public.sharepoint.com/Pages/2014/03/Solving-SigningCredentials-was-not-initialized-on-Sharepoint-Provider-Hosted-Apps.aspx