clarifying question.

Jim Schaad <[email protected]> wrote:
    > I do not seem to have been doing a good job of explaining the issue
    > that I am raising here, so I am going to go scenario based for a
    > description.

    > (1) I get an access token from an AS with a scope of [
    > "coap://multicast-01", ["responder"]]
    > (2) I join the group associated
    > with that address
    > (3) I then decide to send the message below out
    > encrypted with the group symmetric key and signed with the public key I
    > registered during the join

    >    GET coap://multicast-01/resource1

.... (I numbered the steps)
I believe that (1) was intended to allow you to become a responder for this 
resource.

    > It then processes the get request
    > because it does not know that this is a violation of the scope assigned
    > to me by the AS.

!

    > The only way that I know for the server TimeX to enforce the allowable
    > operations is for that information to be propagated along with the
    > signature public key from the KDC to the server.  One can create a
    > similar scenario on the other side where a client sends a response when
    > it is only authorized as a "requester".

It seems to me that if the access control to the group is a group-shared
symmetric key + asymmetric signature, that each responder requires the list of 
valid signers.
Or, we need LAKE to turn the group key into 1:1.

--
Michael Richardson <[email protected]>, Sandelman Software Works
 -= IPv6 IoT consulting =-



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