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List:       cap-talk
Subject:    RE: [cap-talk] The shared object graph problem
From:       "Karp, Alan H" <alan.karp () hp ! com>
Date:       2005-05-24 21:20:58
Message-ID: C49F2ECB5C14DE44898E96EB46147AF523B677 () cacexc12 ! americas ! cpqcorp ! net
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> -----Original Message-----
> From: cap-talk-bounces@mail.eros-os.org 
> [mailto:cap-talk-bounces@mail.eros-os.org] On Behalf Of 
> Jonathan S. Shapiro
> Sent: Tuesday, May 24, 2005 12:08 PM
> To: General discussions concerning capability systems.
> Subject: RE: [cap-talk] The shared object graph problem
> 
> On Mon, 2005-05-23 at 10:42 -0700, Karp, Alan H wrote:
> > If Alice receives two capabilities through the same 
> membrane, then it's
> > possible for her to test EQ locally.  If the capabilities Alice is
> > testing came from Bob and Carol, local EQ and separate revocation of
> > Bob's and Carol's capabilities appear to be incompatible.  If Alice
> > receives them through different membranes, she can't test EQ locally
> > unless there's some metadata associated with the capability.  Right?
> 
> I think this captures the problem, though I think it isn't quite this
> bad.
> 
> If Alice receives a cap from Bob and expects to retain it or otherwise
> perform operations on it reliably, Alice needs to do an exchange
> protocol with the originating server. Once this is done, Alice (a) can
> do local EQ, and (b) is no longer hazarded by Bob's demise.

A process I've been calling "introduction".  Of course, in order to do
EQ she'll also have to exchange the capability she got from Carol.  At
that point she can be told that it is EQ to the one from Bob that she
exchanged.  A side question is what it means if the exchange is refused.

________________________
Alan Karp
Principal Scientist
Virus Safe Computing Initiative
Hewlett-Packard Laboratories
1501 Page Mill Road
Palo Alto, CA 94304
(650) 857-3967, fax (650) 857-7029
https://ecardfile.com/id/Alan_Karp
http://www.hpl.hp.com/personal/Alan_Karp
  

["Karp, Alan H.vcf" (text/x-vcard)]

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