title: FormsAuthentication.SetAuthCookie doesn't [Authorize] in MVC 5
body: <p>I created a brand new ASP.NET MVC 5 project to test the <code>[Authorize]</code> attribute with <code>FormsAuthentication.SetAuthCookie</code>. I simply set a cookie in one action (in my Home controller):</p>
  
  <pre><code>    public ActionResult About()
      {
          FormsAuthentication.SetAuthCookie("someUser", false);
  </code></pre>
  
  <p>And I limit access to another:</p>
  
  <pre><code>    [Authorize]
      public ActionResult Contact()
      {
  </code></pre>
  
  <p>When I launch my web page and navigate to <code>/home/contact</code>, I am correctly redirected to a login page. Then I go to <code>/home/about</code>, get my cookie, and go back to the contact page. But I'm still redirected to the login page -- the cookie does not authenticate/authorize me.</p>
  
  <p>In the debugger, <code>HttpContext.User.Identity.IsAuthenticated == false</code> when I load the About page multiple times (that is to say, it never sees me as being authenticated even after setting an auth cookie).</p>
  
  <p>Is there some extra step that must be done here? I shouldn't need to set my own IPrincipal for basic authentication, should I?</p>