Subject: [Ecrit] media security & phone bcp

From: Hannes Tschofenig <[email-masked]>
Date: Tue, 30 Oct 2007 00:52:22 +0100

I noticed that phone bcp talks about signaling security but it does not 
speak about media security.
I believe SRTP is possible for emergency calls. For key management I 
would mandate Security Descriptions [RFC4568]

Sounds reasonable?

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From: Richard Barnes <[email-masked]>
Date: Tue, 30 Oct 2007 02:05:26 -0400

Hannes,

That's a good catch.  There should be a discussion of media security in 
phonebcp.  Could you clarify why you think SDES is the mechanism of choice?

--Richard

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From: "Brian Rosen" <[email-masked]>
Date: Tue, 30 Oct 2007 03:23:39 -0400

My problem with this is that the state of media security in SIP can best be
described as chaotic.  There are few interoperable implementations.  The
basic SRTP is easy to specify, but there is no clear guidance we can give on
the signaling to establish the SRTP connections.  As you know, there is work
on this in rtpsec, but that appears to be far from solidifying as yet.

Brian

> -----Original Message-----
> From: Hannes Tschofenig [mailto:[email-masked]]
> Sent: Monday, October 29, 2007 7:52 PM
> To: ECRIT
> Subject: [Ecrit] media security & phone bcp
>

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From: "Stark, Barbara" <[email-masked]>
Date: Tue, 30 Oct 2007 06:46:42 -0400

I agree with Brian's assessment. Also, SRTP is "heavy". Currently,
there's no push for the added expense of SRTP to be supported in
consumer end devices. Until it becomes common in end devices, I can't
support mandating it for use with emergency calls. And I think it's
going to be a long time (maybe a really long time) before it gets
implemented in consumer end devices.
Barbara

-----Original Message-----
From: Brian Rosen [mailto:[email-masked]] 
Sent: Tuesday, October 30, 2007 3:24 AM
To: 'Hannes Tschofenig'; 'ECRIT'
Subject: RE: [Ecrit] media security & phone bcp

My problem with this is that the state of media security in SIP can best
be
described as chaotic.  There are few interoperable implementations.  The
basic SRTP is easy to specify, but there is no clear guidance we can
give on
the signaling to establish the SRTP connections.  As you know, there is
work
on this in rtpsec, but that appears to be far from solidifying as yet.

Brian

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From: Henning Schulzrinne <[email-masked]>
Date: Tue, 30 Oct 2007 10:14:44 -0400

I agree with Brian here; this requirement will likely just be ignored  
and should best be done in a revision of the document in a year or  
two, once we have a better idea which combination of techniques is  
generally being implemented. As far as I know, the SIP and MMUSIC WGs  
have not reached consensus on this.

It is not clear that we have a motivation that makes all emergency  
media so much more privacy-sensitive than all other phone calls.