RE: Problems with draft-ietf-mmusic-sdescriptions-09.txt

> I guess this work could be used by many application protocols but the
one I
> am most interested in is SIP so let me answer your question for that
one.

Most likely it will be used by SIP.

> The application, a SIP UA, in this case needs to decide how it wants
the
> material to be protected - if it does not care, it could just send it.
If it
> wants to enforce all hops use hop by hop protection, it would use a
sips
> URL, it it wanted to enforce end to end protection, it could use the
S/MIME
> stuff. All these are somewhat described in 3261.

I haven't touched SIP for quite a while - and I don't think may SIP
applications (especially those from 3GPP/3GPP2) support S/MIME.
Since this proposal suggests sending keys themselves - unless it is
demonstrated how the application will *enforce* end-to-end security, the
proposed protocol has a nice hop-to-hop hole in it.

> I imagine for other application that use this the answer would be
similar.



> Any application that has keying material needs to decide how and when
to
> protect it and not much some lower level thing can do about that.

Especially since there is no pre-defined lower-level stuff.

On 5/2/05 8:59 AM, "Marcus Leech" <mleech <at> nortel.com> wrote:
> One of my colleagues pointed me at this document.    Quite apart from
> whatever problems might exist in the protocol itself, it makes an
assumption
> that it will always run of "some kind of secure channel".  It's not
clear
> how that's enforced, and given that this protocol is carrying keying
material
> for SRTP, it makes me nervous.

I don't think it can be enforced from within SIP. Also, I question
appropriate-ness of hop-to-hop security for keying material, even if it
could be enforced (which I think it can't).

> Can others take a look and tell me whether I'm out to lunch or not?
[In
> this specific case, not the more general case of me being out to
lunch,
> since I already know that  ].

Leaving alone the general case - yes this particular draft raises
security concerns (IMHO).