Secure communication between two process

FROM : Vincent Pottier
DATE : Thu Dec 16 23:38:43 2004

Hello list,
   My project contain two elements, one application and one daemon (in
fact a startupItem). Daemon perform privilege operation incoming from
the application.
   I'd like to know the best way to perform communication between
application and daemon, I know I can use Notification with
NSNotificationPostToAllSessions but it's not secure at all, every
application can send a notification, NSConnection don't looks better...
   Getting authorization is not a problem, the problem is to transmit it
to the daemon.
   If someone have an idea or a sample code
Thanks in advance
Vincent