Subject: [Sip] Comment on draft-munakata-sip-privacy-new

From: "Elwell, John" <[email-masked]>
Date: Tue, 17 Jul 2007 11:54:23 +0100

Mayumi,

"If the "temp-gruu" URI parameter and value exist within the REGISTER
   response, the user agent SHOULD use the value of the "temp-gruu" as
   an anonymous URI representing the originator.  This URI SHOULD be
   used for Contact and From, for example, wherever the originator of
   the URI is required."
I have not heard of using a temp GRUU in the From header field before.
Normally the From header field contains the AoR, not the contact URI,
and where anonymity is required if contains a value such as
sip:[email-masked] or a domain part of "anonymous.invalid". Of
course, a temp GRUU does provide anonymity (given that you are prepared
to disclose the domain), so I suppose it might work. There may be one or
two side effects:

1. A UAS that simply displays the From URI would display the temp GRUU
rather than something like "sip:[email-masked]".

2. If the outbound proxy provides an Authentication Service, it would
need to recognise that this is a temporary GRUU and sign the Identity
header field even though the From URI does not match the identity in the
Proxy-Authorization header field.

I would like to hear opinions on this.

John

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---

From: Shida Schubert <[email-masked]>
Date: Tue, 17 Jul 2007 11:13:06 -0700

John;

 My comments inline..

> rather than something like "sip:[email-masked]".
  I agree, this is a mistake on our side and the From URI should not 
utilize the temp-gruu, and instead
should utilize anonymous URI such as "sip:[email-masked]". One 
could try to use the
"anonymous.invalid" domain but this will interfere with the SIP Identity 
which heavily relies
on domain of the From header field. We will fix the text here to ensure 
temp-gruu is not
used for From URI.
> Proxy-Authorization header field.
 If From header is populated using anonymous URI 
([email-masked]),with domain portion equal to 
the domain for which the outbound proxy is responsible, this won't be 
problematic. The identity
service would use the information in the proxy-authorization to identity 
the user and will simply
judge whether that user has a right to send out request while 
withholding its identity.

 If temp-gruu is used as it is currently written, outbound proxy would 
need to look up the
location-service and see if the AoR associated with the credential is 
indeed associated with
the temp-gruu in the request. The text will be changed to populate the 
 From header field with
anonymous URI as mentioned above, so this really is not a concern anymore.

 As a side note, if there is a concern about revealing its domain name 
to the peer, one would probably
need to utilize a dedicated anonymous service(anonymity provider) which 
provides URI to be used in
 From while withholding its original domain name etc.
 
 Regards
  Shida