Re: [Dtls-iot] FW: New Version Notification for draft-keoh-dice-multicast-security-08.txt

[Carsten Bormann <[e-mail]>]

I consider a definition of (integrity) protection more useful that figures in the attacker.
If an attacker can steal a lamp out of my home and tamper with it, I probably have larger issues than whether they can do some morse code on my lights.  (If they can “hack” it, they already can do the morse code thing.)
So, yes, I consider group keying to provide integrity protection — against attackers outside the group.

> application-based group keying is still significant progress for those cases where the attack model doesn’t rule out group keying.
> 
> The use cases where this works all seem to involve a secure processing element and that's not exactly within the DICE charter.

Tamper-proofing is not required for the above use case.

> The most successful group keying system I'm aware of is pay TV (either satellite or cable).  Those systems - obviously - use a secure processing element (e.g. smart card or built in) to manage group keys and decryption based on credentials.

This has a quite different attack model — here you hand over the entire environment (smart card, decoder) to any interested attacker.  This is not the case we are interested in.

> I literally can't think of a use case without an SPE where the attack model doesn't rule out group keying for integrity protection and most attack models for most use cases rule it out for confidentiality.

See above.

Grüße, Carsten