Notification authentication -- more things left out of the PIDF draft

In a setting in which security is important, one must provide a means
for a client that is watching a presence entity to verify that
notifications about the presence entity originated at the presence
server to which the watcher is subscribed.  To allow a notification to
be signed, it is important to define a standard way in which PIDF is
embedded into CPIM-MSGFMT content, but the most important aspect of
this embedding is that the From field identify the server that is
sending the notification, and not identify the presence entity that is
contained in the content.  The From field of a subscription request
names a presence entity and identifies the principal that originated
the request.  If the From field of a notification names a presence
entity, than it is erroneously identifying a client as the source of a
notification, where as the true originator of the notification is the
presence server.  Failure to correctly identify the principal of a
notification negates the value of using digital signatures for
authentication.

For more on this topic, see:

   http://simp.mitre.org/drafts/simp_server.html#security

and 

   http://simp.mitre.org/drafts/simp_server.html#notify

John


  [reminder: [email protected] for non-technical discussions, please]