MVC4应用程序和WCF:如何创建自定义身份验证?

I'm playing with Visual Studio and i've created a MVC4 application project that contains a authentication part (the default one). In the other hand, i've a web service (WCF) liked to a database managed by SQL server that contains Users(login, password) table. I'd like to change the "default" authentication with a one linked to the data that are provided by the web service. So, to be clear : How to query a remote database to check login/pwd correctness ?I'm playing with Visual Studio and i've created