Subject: [Sip] Questions on new draft identity concepts posted

From: "Chiou, Mark" <[email-masked]>
Date: Fri, 19 Apr 2002 15:20:57 -0500

Hi Dean,

I have the following questions:

	1. What is the purpose of this identity draft?
	   If it is for network usage, then identity info shall not be delivered to the UAS 
	   when the Privacy is set to Anonymous.
	2. Why is using MIME type instead of new optional header field?
	   Why Call-ID and Date are required?
	   Why is only encrypted for Anonymous calls? How about non-Anonymous calls?
	3. Can we consider forwarding scenario? Such that the forwarding Identity is included.
	   I know this does not apply to IP world when 3xx is returned to the UAC. 
	   But it is very popular in the PSTN interwork scenarios.

	4. In page 14, 5.4 example of the Content-Length:147 of the Unique-Boundary-1.
	   Do you think the length shall include the length of Unique-boundary42.
	5. There are several IDs that we need to consider all together instead of 
	   separating them: 
		1) User, who actually makes the call 
		2) actual Subscriber, who subscribes the service 
	  	3) identity known by the Service Provider, who provides the service
		4) The last forwarding-by identity known by the Service Provider, 
		   who provides the service
		5) Billing Identity, who actually pays the bill
	   Not all of above are needed by the UAS, but all are needed by the Network.
	6. Every identity shall have its own privacy attribute, 
	   so we should address Identity and Privacy together.
Regards,

Mark Chiou

-----Original Message-----
From: Dean Willis [mailto:[email-masked]]
Sent: Wednesday, April 17, 2002 6:24 PM
To: [email-masked]
Subject: [Sip] new drafts relating to privacy and identity concepts
posted

Please review:

http://www.softarmor.com/sipwg/drafts/draft-peterson-sip-privacy-longter
m-00.txt

http://www.softarmor.com/sipwg/drafts/draft-peterson-sip-identity-00.txt

They've been sent into the internet-drafts repository and should appear
there shortly.

--
Dean

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_______________________________________________
Sip mailing list  https://www1.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol
Use [email-masked] for questions on current sip
Use [email-masked] for new developments on the application of sip

---

From: "Peterson, Jon" <[email-masked]>
Date: Fri, 19 Apr 2002 17:42:37 -0500

I'd like to take a stab at these questions. Some responses below.

Jon Peterson 
NeuStar, Inc.

> From: Chiou, Mark [mailto:[email-masked]]
> Sent: Friday, April 19, 2002 1:21 PM
> To: Dean Willis
> Cc: [email-masked]
> Subject: [Sip] Questions on new draft identity concepts posted
> 
> 
> Hi Dean,
> 
> 	   If it is for network usage, then identity info shall 
>  not be delivered to the UAS when the Privacy is set to Anonymous.

The purpose of this identity draft is to define a general-purpose way for an
'authentication service' to provide a secure, verified identity for the
originator of a request that can be inspected by any potential recipients.
Privacy concerns are addressed in the draft - the identity will not be
decipherable by a UAS when privacy is requested.

> 	2. Why is using MIME type instead of new optional header field?

This is a good question, and unfortunately a deep one. That short story is
that it is easier to stage the required security properties (integrity via
signature with certificate, replay protection, optional confidentiality) in
a body than in a header. With a body, we can also do this through baseline
bis09 security mechanisms without having to invent anything new.

> 	   Why Call-ID and Date are required?

To provide reference integrity to the request, and a small amount of replay
protection, respectively.

> 	   Why is only encrypted for Anonymous calls? How about 

If privacy is not required, then presumably the identity can and should be
shared with any potential recipient. Seeing a network-verified identity
might make a recipient more comfortable that they know the identity of the
originator of a request. Users should only request privacy when they need it
- I often don't accept phone calls that are from a blocked ID, myself.

> 	   But it is very popular in the PSTN interwork scenarios.

I have some hopes that the 'auth-id' system described in this draft (or
whatever it eventually ends up being when the draft is done) will be
applicable to things like forwarding and referral. I think it may already
help out with some identity problems in forwarding.

> 	   Do you think the length shall include the length of 

Those MIME types do get confusing  when they're embedded, eh? The
Content-Length in that example does not pretend to be accurate - maybe I'll
update it to a less inaccurate value. However, the unique-boundaries, are, I
hope, correctly aligned.

> 	   Not all of above are needed by the UAS, but all are 

All interesting concepts, and as you'll note I left open the possibility
that other information could be put into the 'auth-id' token as necessary.
For the time being, the draft is only concerned, really, with (1) and (3)
above. I'm surprised you make a distinction between (2) and (5) - I though
the fact that (2) encompasses (5) is what differentiates (2) from (1). Then
again, I don't really understand (2) that well either. Anyway, I don't think
the identity draft needs to get into any of these details - this mechanism
could be extended at a later time to accomodate these concepts as necessary.
SIP needs to grapple a bit with what these other sorts of identities are
before we figure out how to stuff them into secured bodies.

> 	   so we should address Identity and Privacy together.

This identity draft does depend on and extend the accompanying privacy
draft. Frankly, I think ascribing a new privacy attribute to every
conceivable form of identity is unnecessary, and possibly dangerous. A user
shouldn't have to know, when they create a message, all of the various
headers in a message for which they need privacy - merely what kind of
privacy they need. While there is definitely a relationship between identity
and privacy, I think they are separable and they benefit from separate
consideration.

m-00.txt

--
Dean