WPF application authentication with Google

Question

I have found many different solutions with OAuth and either with some libraries or with pure requests (https://github.com/googlesamples/oauth-apps-for-windows).

Howe

Answer 1

I think you are missing the point on what the OAuth is, start by reading this and here is a simple description of the flow.

which will just make sure that user can also login with his Google e-mail-password pair, I don't need a returned token for the further use

There is no api for user/pass validation, and the token is the whole point of the OAuth. A user with existing email should be able to login if indeed you registered your application with google. Also i see no point in prior validation of user/pass, just add the button.