Forum Verify User across site
 

I have a website that is primarily done in JSP, however we use vBulletin for the forums. My question is i want to be able for a user to be authenticated on the JSP side as well as the vBulletin PHP side.

What can i do if the user puts his login/password on the JSP... authenticate the password from the vBulletin user table... i don't remember what the encryption type is on the password in the table. If authenticated, i can set a session in the JSP, but how do i tell PHP the person is now authenticated on the PHP side... And vice versa

Thanks for your thoughts or tips.