On 7/27/2016 5:56 PM, Michael Richardson wrote:
Probably not - as long as symmetric key group communications is used as a control protocol.Kathleen Moriarty <kathleen.moriarty.i...@gmail.com> wrote: >> Mohit Sethi <mohit.m.se...@ericsson.com> wrote: >> > designed/developed/specified for their use-case. I could definitely >> > see some IoT startup building a solution that switches on the lights >> > in a room as soon as you unlock the door (thus keeping them in the >> > same group). >> >> Or perhaps more usefully, turning the lights (and the oven) off when you >> leave the house.> Good points, but you could do this without them being in the same > group with some controller that managed the interactions with each. > This would be a good set of examples for the security considerations > sections, providing guidance to use a controller rather than group > keys to perform useful functions like these. I agree. Perhaps we could convince Mike St.Johns to write that section?
And ACE has the right mechanisms to make this work well.
I agree - public key systems. But that seems to be out of scope here.
We've had a thread now on performance of asymmetrical crypto, and it seems that controllers ought to be able to talk to other controllers quickly enough to make this workable. We should also consider whether we can use hash-chains, like S/KEY did, to authenticate messages that should only go out in emergencies. Such messages would clearly *need* to be multicast, but once used, they can never be reused. They can't be originated by more than one sender though.... so it's really the message stored by the "EMERGENCY STOP" button.
That's an interesting idea - but AIRC, hash chains could be originated by anyone that held the signing/verification key.
Again - if you don't touch the physical world, I'm pretty much not worried about how screwed up the protocol is. But you touch the physical world.
Let's do this the right way. Let's not bow to the "tyranny of the light switch" in accepting solutions that are NOT secure, even for the limited scope they are proposing.
Later, Mike
-- Michael Richardson <mcr+i...@sandelman.ca>, Sandelman Software Works -= IPv6 IoT consulting =- _______________________________________________ Ace mailing list Ace@ietf.org https://www.ietf.org/mailman/listinfo/ace
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