I am using ASPNet Identity to implement security in my web application.
There is a requirements where in, I need to extend the IdentityRole and IdentityUser.
You can inherit from IdentityRole in your application the same way that you do your IdentityUser. Why do you need to extend IdentityRole? Please take a look at the following article which explains in detail what you are trying to do http://typecastexception.com/post/2014/02/13/ASPNET-MVC-5-Identity-Extending-and-Modifying-Roles.aspx