Securing named event is being set from particular process.

Question

Hi,
I have two process P1 & P2 on the same machine P2 is listening for a named event "Terminate" being set in P1.
EventWaitHandle watcherTerminationEvent = null;
WaitHandle[] waitHandles = new WaitHandle[1];
watcherTerminationEvent = new EventWaitHandle(false, EventResetMode.AutoReset,"Terminate");
waitHandles[0] = watcherTerminationEvent;
var exitcode = WaitHandle.WaitAny(waitHandles);


Now, there is a chance of setting this event by  any process in the system(P3,P5....), but i need to restrict this only to P1, how can i achieve that.
Thanks
Vinod