Re: [Ace] Adoption of Low Latency Group Communication Security Work in ACE

[Michael StJohns <[e-mail]>]

On 7/21/2016 5:29 AM, Ludwig Seitz wrote:
> On 2016-07-21 11:04, Michael Richardson wrote:
>>
>> Why will ACE succeed when DICE failed?
>> Does ACE now have some knowledge or mechanism that DICE couldn't have 
>> created
>> because it was out of scope?
>>
>
> ACE is (also) about authorization, which DICE wasn't. A compromised 
> lightbulb might well have the possibility to talk to a door lock 
> (using it's group key), but it would lack the authorization to do 
> anything with the lock.
>
> IMHO that's what ACE add that DICE didn't have (and wasn't chartered 
> to have).

Hi Ludwig -

Sorry - you are incorrect.

The group key is also the authorization key in the model proposed. Any 
entity that holds that key can forge a message that can cause the action 
authorized by the issuance of that key. In your example, assuming that 
the door lock and the lightbulb share the same group key, then 
compromising the lightbulb allows you to control the door lock.

In general, authentication comes with the key that you have - 
authorization is then tied to that key.  In DTLS  (as in TLS), your 
session key is also your authorization key once your TLS session is tied 
to a particular identity (e.g. via an HTTP login, via a client cert 
exchange, via OAuth).

So - cosmetic differences only.

Mike






>
> /Ludwig
>
>
>
>
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