Just use the ASP.NET Identity framework and write your own provider. You will get all the great benefits like encryption for free. Without any effort. To lose all this good stuff just because somebody doesn't know ASP.NET is just not reasonable (imho). It has very little to do with ASP.NET because it is so loosely-coupled.
http://www.asp.net/identity gives you an idea of how to sit on top of OWIN.
Custom provider examples
And here is mine for Oracle databases, very simple to understand I would say. It should give you an idea on how to implement your own one:
https://github.com/timmkrause/AspNet.Identity.OracleProvider