[XCON] Re: [MMUSIC] BFCP: SDP usage and k=

[Mark Baugher <mbaugher at cisco.com>]

On Feb 12, 2005, at 1:01 PM, Nathan Allen Stratton wrote:
> >
...
> > I glanced at the usage of k= in this I-D, which says that it encodes a
> > shared secret.  But where does it specify what kind of shared secret?
> > What algorithm is used for computing the digest?  I did not study the
> > draft and may be missing something.  If it is completely specified 
> > then
> > it avoids the general problem that we found with k= in the past, 
> > namely
> > that there is no way to identify the transform to be used and pass
> > additional cryptographic and session parameters that practically 
> > always
> > need to be communicated with a cryptographic key.  If
> > draft-ietf-mmusic-sdp-bfcp-00.txt does not have these problems and k=
> > signals all needed information, then there may be no problem.
>
> My understanding of mmusic-kmgmt-ext-13 is that it is open to using 
> many
> different key management protocols. I however am in the dark as to what
> the draft use of mikey is, I think based on RFC 7311 it is AES, but I 
> am
> not sure.

The specification that we're discussing makes no mention of MIKEY or 
the kmgmt I-D.  k= is a much different approach than kmgmt.   If the 
authors were to replace k= with something more expressive, then I'd 
expect that they would use sdescriptions.

The question that I have raised and that I don't think has been 
answered is whether k= is sufficient for carrying a digest key.  The 
authors could choose to use MIKEY/kmgmt or they could use 
sdescriptions.  Maybe k= meets the application requirements.  I don't 
know, which is why I asked the question: Is there a need to specify the 
algorithm with the key?

Mark

Mark
> > <>
> Nathan Stratton                                   BroadVoice, Inc.
> nathan at robotics.net                                 Talk IS Cheap
> http://www.robotics.net                           
> http://www.broadvoice.com

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