@dan But is it possible to initiate the FA session?
Custom form is used for registration, it's on a separate page than the actual application (X). Let's say after the registration I get the token from FA on the server side. I can send it back to the client side and save it there. This way, when the user visits login page, I'm able to send the token to the server and from there to FA for checking.
But what if there's a second separate application (Y). In this app user tries to login, gets redirected to the FA login page. However, he's not recognized by FA here and is asked to enter his password.
I've read and tested your SSO example app, but it doesn't answer my case. Is it possible to do so that FA recognizes user when he is redirected from application Y after registration in application X's custom form? Thanks