I have a PHP application that is successfully authenticating against a CAS server. One of the features supported by the application is impersonation; a user with the appropriate privileges can impersonate another of the application. Generally, this isn't a problem because the app itself can keep track of who the user is impersonating and manage privileges (which are based on username).

A new requirement has come up, though, that requires the original app to include, via an iframe, content from a second PHP app that is also CAS-enabled. Somehow, I need for the second app to know whether impersonation is happening in the first. I don't want to pass usernames around for security reasons, so I'm wondering whether I can offload the responsibility for handling impersonation to the CAS server which is shared by both apps.

Thanks.