Re: Comment on the paper by Rotondi, et al.

Could you link to this paper?


On Fri, Jan 31, 2014 at 12:50 AM, Karp, Alan H <[email protected]> wrote:

>  I’m reading the paper section by section as time permits, and I just
> finished the piece on revocation.  Here I want to comment on the feature
> that allows revocation of just the capability and not those delegated from
> it.  I believe that feature has a serious flaw, but Marc Stiegler has come
> up with the correct variant.
>
>
>
> As described in the paper, a revocation request can be for the capability
> itself or the capability and all capabilities delegated from it.  The
> problem with the former is that it is too easy to bypass the revocation.
> Say that Alice delegates a capability that expires in a year to Bob, a
> manager in her department.  Bob re-delegates capabilities with subsets of
> the permissions to people reporting to him.  Three months later, Bob leaves
> the company under suspicion of stealing company secrets.  Alice clearly
> wants to revoke Bob’s capability, but she doesn’t want to disrupt the work
> of people in his former department.  As a result, she revokes Bob’s
> capability but not the capabilities delegated from it.  Unfortunately, one
> of those delegated capabilities was one Bob delegated to himself with a key
> not controlled by the company.  The result is that Bob retains access even
> after being fired.
>
>
>
> Marc Stiegler’s solution to Alice’s dilemma uses the distinction between
> vetted and unvetted identities.  Say that the enterprise provides a
> mechanism by which Bob denotes the target of the delegation by specifying
> someone in the company directory.  That’s a vetted identity.  If Bob
> delegates to someone not known to the enterprise, that’s an unvetted
> identity.  When Bob’s capability is revoked, the rule is to revoke all
> capabilities delegated to unvetted identities but leave the others.
>
>
>
> ________________________
>
> Alan Karp
>
> Principal Scientist
>
> Enterprise Services, Office of the CTO
>
> Hewlett-Packard Company
>
> 1501 Page Mill Road
>
> Palo Alto, CA 94304
>
> (650) 857-3967, fax (650) 857-7029
>
> http://www.hpl.hp.com/personal/Alan_Karp
>
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>

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