Basic authentication and session management library for PHP?

Question

I know questions like this have been asked numerous times, but not quite this one. Forgive me if I overlooked an obvious duplicate.

In the core of many of my web app

Answer 1

There are several OpenID libraries available.

http://wiki.openid.net/Libraries#php

For the rest you might as well roll your own, since figuring out someone else's library would probably be more trouble than it's worth.