Re: francois' comments and why RFC4474 not used in the field

I'm not sure I agree with the logic.

It seems to me when e2e security of media, then DTS-SRTP (for UDP) and TLS
(for TCP) makes perfect sense.

If we allow transcoding, then I don't see the point in e2e security, since
it obviously is not e2e. I don't understand what ICE gives you in this case.

If we need transcoding, then we might want instead to have a security mechanism with
the transcoder instead.

For example, we could use DTLS-SRTP where Alice is using the 4474-like mechanism,
but the transcoder is using it's own cert (instead of a self-signed one). That
cert's credentials would already be provisioned in Alice's device. That would 
seem like a simple way to do this.

> -----Original Message-----
> From: Dan Wing [mailto:[email protected]] 
> Sent: Friday, April 03, 2009 10:44
> To: Audet, Francois (SC100:3055); 'Dean Willis'; 'Jiri Kuthan'
> Cc: 'SIP List'; 'Uzelac,Adam'
> Subject: RE: [Sip] francois' comments and why RFC4474 not 
> used in the field
> 
> > > All 5 techniques described in
> > > 
> > 
> http://tools.ietf.org/html/draft-wing-sip-identity-media-02#section-4
> > > accomplish that using TLS, DTLS-SRTP, ICE, HIP, or ZRTP -- any of 
> > > those choices has different tradeoffs.
> > 
> > I'm puzzled by why we would do anything but the DTLS-SRTP 
> (and TLS for 
> > TCP traffic).
> 
> I also prefer TLS.  RFC4474 doesn't require TLS, so ICE is in 
> the draft to demonstrate it is possible to have identity even 
> through a translator and have identity with just RTP (RFC4474 
> provides identity with just RTP).
> 
> However, if we used TLS/DTLS-SRTP for identity it would (a) 
> break transcoding (as discussed) and (b) require deploying 
> SRTP.  If doubt we are willing to do
> (a) and (b).
> 
> -d
> 
> 
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