Authentication

In the authentication process in Jigsaw, I have some problems to
understand how the persistance works. In more details, when a user
connects to the server, he authenticates once and then all
subsequent requests don't need to be preceded by an authentication.

How does it work? Is the IP address stored somewhere or is there some
internal ID system implemented?

I have browsed classes like GenericAuthFilter but can't see where
the mecanism is done. 

Regards,

ch. Buchs