How to Create a signed_request with JS-SDK to pass to PHP-SDK via Ajax

I use the JS-SDK to Login the Users in my FB-App but directly after the User authorized my App I'm passing a AJAX Request in wich i need the FB-Session in Firefox its working as it should without any special data about the FB-Session bu开发者_开发问答t in Chrome and Safari the FB-Session is lost.

So I'm looking for a solution to fix that and thought about sending an signed_request in the Request to save the FB-Session.

JS-SDK is creating a special cookie for your app on a client called fbsr_APP_ID, which is a signed request, you should be able to get it with every ajax call, verify and obtain access token. No need to pass anything else in order to identify the user.

hope this helps