title: IAuthenticationFilter interface implementation in asp.net MVC
body: <p>I was going through the Controller class in ASP.NET MVC, and found out that it implements IAuthenticationFilter interface. However I am unable to understand how can I implement, its methods OnAuthentication() and OnAuthenticationChallenge(), in my controller and when these will be called.</p>
  
  <p>It will be very helpful if someone can explain it to me or share with me any link that explains this. Even I was unable to find any resource on this in MSDN.</p>