Re: [Sipping] Decision needed on final issue withdraft-ietf-sipping-update-pai-07

["DRAGE, Keith \(Keith\)" <drage at alcatel-lucent.com>]

> We recently 
> agreed to remove specification of PAI in responses because 
> there is no standardised means of authenticating a UAS. Brett 
> 

So what exactly is the change you are making here.

As far as I am concerned RFC 3325 allowed PAI in responses. There was
some debate a long while ago on this but that is used by many
implementations.

In the 3GPP case, it is based on the P-Called-ID header transferred
internally, i.e. the request was delivered to this terminal which was an
authenticated user based on the registration, and a security association
created at that time. Note that we are making some assumptions here, but
those assumption are valid in this scenario.

So I do not believe you should be changing the underlying RFC 3325 in
this respect.

Regards

Keith

> -----Original Message-----
> From: sipping-bounces at ietf.org 
> [mailto:sipping-bounces at ietf.org] On Behalf Of Elwell, John
> Sent: Thursday, October 23, 2008 3:18 PM
> To: sipping at ietf.org
> Subject: [Sipping] Decision needed on final issue 
> withdraft-ietf-sipping-update-pai-07
> 
> I need a decision on one outstanding issue. We previously 
> agreed that PAI could be used in any request. We recently 
> agreed to remove specification of PAI in responses because 
> there is no standardised means of authenticating a UAS. Brett 
> Tate pointed out that likewise there is no standardised means 
> of authenticating a UAC when it sends CANCEL or ACK (these 
> cannot be challenged, and cannot be rejected if 
> authentication is wrong). I have so far received no further 
> opinions on this. To be consistent I believe we have to make 
> exceptions of CANCEL and ACK and say that PAI cannot be used 
> with these methods.
> 
> If I receive no objections by 26th October I will update the 
> draft on 27th.
> 
> John
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