Force Facebook to ask user password when using OpenGraph

Question

I use Facebook OAuth 2.0 to register new users to my website. After which they can also login using Facebook.

If a user is already logged in at Facebook, and registers at my site, I would like Facebook to ask again for the password of the current user so I know for sure the user that registers is the person logged in at Facebook. Because often home-computers are being used my multiple people, and people tend not to logout from Facebook.

Answer 1

You can't. It's up to Facebook to decide when to prompt the user for password, not you. You can always put up an additional prompt asking the user to confirm who they are later.

Answer 2

If you are using asp.net and C#(Facebook API's For .NET available on codeplex.com),

Add this line in the Page_PreInit Event

      base.RequireLogin=true;

If the user is logged in, it will not ask for the login, but if the user it not logged in, it will redirect to you the Facebook login page.