ASP.NET Identity in Visual Studio 2013 is a way to simplify the boring but essential tasks of managing user data and establishing a more effective membership system.
If your application is using ASP.NET Identity or other membership systems such as SQL, Universal or Simple membership, then you might be running into the following issue. If you are using ASP.NET Identity 2.x, the query for getting profile values (among other things) uses the UPPER() function on Username - this causes any indexes on username to be ignored.
ASP.NET Identity is Microsoft’s fourth and by far its best iteration of an authentication/authorization system that’s built right into ASP.NET. It’s super flexible and extensible, yet easy to use and ready to go right out of the box.
How to use 2 Factor Authentication in ASP.NET Identity 2.o with Google Authenticator. This blog post is going to show you exactly how to do it.