Subject: [core] Stephen Farrell's No Objection on draft-ietf-core-groupcomm-21: (with COMMENT)

From: "Stephen Farrell" <[email-masked]>
Date: Thu, 21 Aug 2014 08:15:31 -0700

Stephen Farrell has entered the following ballot position for
draft-ietf-core-groupcomm-21: No Objection

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COMMENT:
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Sorry, I only had time to quickly scan this. 

- For a non MC IP addr, how does one know a URI is for a
group?

- 5.3.3: That draft-keoh draft is quite controversial in the
DICE WG. The question there is whether or not its at all
sensible to try do group security in the DTLS record layer. I
think you really ought recognise that, since its quite
possible that a very different solution will be needed in
reality.

- Thanks for 5.4! I think you should also note that even with
encryption providing confidentiality, traffic analysis could
be a powerful tool against CoAP and group communication, so
future work with CoAP and developers/deployers should also
take into account traffic analsyis. To use your fav example,
its not hard to detect the lights being turned on or off even
if that's done via ciphertext is it?

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From: Brian Haberman <[email-masked]>
Date: Thu, 21 Aug 2014 11:23:46 -0400

> http://datatracker.ietf.org/doc/draft-ietf-core-groupcomm/

The IP address is in a special range.  If you have a domain name, you
have to resolve it to the IP address to determine if it falls in the range.

Brian