Re: [COSE] Multicast Use Case

[Hannes Tschofenig <[e-mail]>]

Hi Stephen,

the discussion in DICE was controversial because there was some
reluctance of relying on symmetric keys since it allows anyone in the
multicast group to inject messages without the ability to authenticate
the sender.

I had a chance to look more into this issue with our participation in an
EU funded lighting project and I believe that the use of symmetric keys
in combination with a key distribution is OK. (The project is called
OpenAIS and consists of a number of the big players in Europe in the
professional lighting sector.) Of course, we will have to discuss this
in more detail in the ACE working group when we get to that point.

To come up with a comparison we obviously have to compare the solution
we would be using at the DTLS layer with an application layer solution.
That's what I had been trying to do here.

We also did not find other use cases that the same type of requirements
as professional lighting has. Other use cases may not have the same low
latency requirements, may not need to rely on IP multicast, or have
higher security requirements.

Hence, lighting does not introduce a generic mechanism but it is still
an important enough area to standardize a solution. I still believe we
should standardize solutions in the IETF that are relevant only for
certain industry sectors.

Ciao
Hannes

PS: In general, my initial review was not really about a specific use
case but rather about the fact that (a) the currently provided examples
were difficult to understand since they didn't contain a lot of comments
and (b) they did contain anything I was looking for. They most likely
have their origin in other use cases.


On 09/01/2015 01:17 AM, Stephen Farrell wrote:
> 
> 
> On 31/08/15 23:35, Carsten Bormann wrote:
>> Jim Schaad wrote:
>>> I did not find the keoh draft because it expired at the beginning of
>>> July.   Which is the draft that I should be looking at?
>>>
>>
>> Now you got me confused.
>>
>> https://tools.ietf.org/html/draft-keoh-dice-multicast-security-08
>>
>> expired on January 4, 2015.  Are we talking about the same documents?
> 
> And... the proposal for the dice WG to adopt that functionality
> (regardless of draft) has been controversial. So I think that means
> that one cannot directly compare encoding sizes, as we do not know
> that a DTLS approach to multicast is workable. I'n not saying here
> that one cannot depend on what's in these drafts, but rather that
> we might not be doing an apples to apples comparison.
> 
> S.
> 
> 
>>
>> Grüße, Carsten
>>
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