Subject: RE: Private Info in To/From (was RE: FW: [Sip] Comment, SIP Priva cy draft)

From: "Mark Watson"<[email-masked]>
Date: Tue, 2 Apr 2002 17:16:19 +0100

Dean wrote:

> 
> "The SIP protocol explicitly sends the From and To fields to the
> destination UA. Therefore the sending UA should only insert 
> information
> in the From and To fields that is intended to be delivered to 
> other UAs
> and potentially displayed to the user of the other UA. If the user of
> the UA wishes to remain anonymous, they must not insert any 
> information
> into the From or To fields which compromises this anonymity. This same
> caveat applies to every other aspect of SIP, including headers and
> bodies, except for those elements which are explicitly removed or
> encrypted by intermediate elements known to the UA."
> 

OK, so let's work with this and see where we get...

1) The UA may insert information which later becomes private due to the
operation of services within the network. The device that detects this must
either edit the From/To fields itself, or explicitly route to an Application
Server which can do this & anything else needed to provide the necessary
privacy.

Is everyone happy with this ? Can we descibe it somewhere ?

2) The From/To fields cannot be used for communication from UE to network
entities of identity information which the user wishes to be kept private
(no way to indicate this)

3GPP has a requirement for information of type (2). They had planned to use
RPID, since this was an element 'which is explicitly removed or encrypted by
intermediate elements known to the UA'. They cannot use the Authentication
mechanism, because in 3GPP this is only done at registration (with first hop
integrity used for subsequent transactions) and the information to transport
can change on a call by call basis.

So what should 3GPP use for this information ?

Regards,

Mark

---

From: Rohan Mahy <[email-masked]>
Date: Tue, 2 Apr 2002 09:45:33 -0800 (Pacific Standard Time)

On Tue, 2 Apr 2002, Mark Watson wrote:

> mechanism, because in 3GPP this is only done at registration

It seems that 3GPP could use an unsolicited Proxy-Authorization header
with the correct public identity identified as the username.

thanks,
-rohan

> (with first hop

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---

From: "Dean Willis" <[email-masked]>
Date: Tue, 2 Apr 2002 22:18:34 -0600

Mark wrote:

---------------
OK, so let's work with this and see where we get... 
1) The UA may insert information which later becomes private due to the
operation of services within the network. The device that detects this
must either edit the From/To fields itself, or explicitly route to an
Application Server which can do this & anything else needed to provide
the necessary privacy.
Is everyone happy with this ? Can we descibe it somewhere ? 
2) The From/To fields cannot be used for communication from UE to
network entities of identity information which the user wishes to be
kept private (no way to indicate this)
3GPP has a requirement for information of type (2). They had planned to
use RPID, since this was an element 'which is explicitly removed or
encrypted by intermediate elements known to the UA'. They cannot use the
Authentication mechanism, because in 3GPP this is only done at
registration (with first hop integrity used for subsequent transactions)
and the information to transport can change on a call by call basis.
So what should 3GPP use for this information ? 
Regards, 
Mark 
-------

1) Absolutely not. The information is what was inserted by the UA. It
cannot become private "somewhere else in the network" for that dialog.
The only way to change it is to make a new dialog. Or maybe that's what
you mean and I'm just being dense.

2) part 1: Yes! Part 2: 3GPP terminals had better be able to use
Authentication anytime it's required by a downstream system or they
aren't conformant to the SIP model as I understand it. Just because they
think they are only going to authenticate REGISTER doesn't mean they can
get away with not supporting it in the other usual transactions. So I'd
suggest that if IETF can come up with something like a third-party
authentication model that adresses the transitive identity expression
requirements, that  3GPP could figure out how to use it.

--
Dean