[linux-elitists] GPG luser rant

Karsten M. Self kmself@ix.netcom.com
Tue Apr 17 15:40:53 PDT 2001

on Mon, Apr 16, 2001 at 10:41:04PM -0400, David Shaw (dshaw@jabberwocky.com) wrote:
> On Fri, Apr 13, 2001 at 12:47:34PM -0700, Karsten M. Self wrote:
> > on Fri, Apr 13, 2001 at 11:50:11AM -0700, Rick Moen (rick@linuxmafia.com) wrote:
> > > I wish it were not the case, but there are not yet very workable
> > > real-world systems for distributing, managing, and revoking keys --
> > > PKI/certificate authority or web-of-trust models are both problematic
> > > in those areas if you aim for both day-to-day practicality and
> > > meaningful authentication.  Much as I would like to hope that these 
> > > are early implementation issues that will be ironed out, the worst of
> > > them appear essential to the authentication models concerned.
> > 
> > There is a distributed public keyserver network.  This seems to work
> > reasonably well from a data distribution standpoint.  I'd be interested
> > in knowing what specific problems exist with it.
> > 
> > Revocation seems to be the real nit.  There isn't an analog, AFAIK, in
> > the PGP model to a "revokation signature".  That is, signing a key to
> > say "I know this key and it is false, invalid, or revoked".
> Quite a while ago, somebody proposed such a thing.  The intent, if I
> recall, was to address the "oops-I-lost-my-key" problem.  If many
> people (presumably acquaintances of the unhappy key owner) signed the
> key with this negative signature, it would effectively revoke the key.
> I don't recall why it did not progress past that, but one of the
> issues raised was the extreme potential for abuse (an unpopular person
> could lose all their keys, present and future, to this).
> As things stand now, aside from harassment signatures which don't
> really affect the web of trust except in a FUD sort of way, the worst
> thing someone can do is refuse to sign a key.  I think that's a good
> thing.

Thing is, cryptospace is an analog to meatspace.

There are credibility attacks on people in both.  If a group of people
gather 'round and try to brand someone as untrustworthy (think:  Rachel
Carlson, _Silent Spring_, Ralph Nader, the US and USSR,...).  There
isn't a magic bullet, but if you do find that someone's fraudulently
representing another person's credibility, you may reduce your own
reliance on that person's trust.  Unfortunately, trust isn't uniform,
even for a given individual.  I may trust someone for one task or role
(fix my care, write code) but not another (watch my kids, share my bed).
Trust can change over time.  Most models fit this only poorly.

Key revocation -- the best trust would be that you have two keys, both
of which you *know* map to the same person, one claiming the other is
invalid.  This works pretty well.  If the other key suddenly challenges
the first again, you've got a problem.  As for those signing to assert
one claim or the other, now you've got some truth-seeking to do.

Keysigning and PKI doesn't certify a state of trust, it documents it in
a credible way.  Your own interpretation of the trail should change with
its own internal consistancy and correlation to reality.

> > Updating key to aquire new signatures is a slightly different story.
> > It's possible to roll through your keyring and re-request the keys from
> > public servers.  This takes some time for me, but is doable, and could
> > be packaged as a scheduled system task.
> gpg --recv-keys `gpg --list-keys 2>/dev/null | grep pub | awk '{print $2}' | sed -e 's/^.*\///'`

That looks familiar ;-)

> (It probably puts more load on the keyserver than is warranted for big
> keyrings, but I only have a handful of keys on my local machine.)
> > Actually, I suspect such security devices may become de rigur as current
> > trusted systems such as credit cards and authentication cards are found
> > to be wanting.  My Palm Pilot already acts somewhat as such a device, in
> > that it holds my access keys to numerous systems -- in an encrypted,
> > password-protected database.  While the Palm isn't the perfect
> > standalone system, it's (again) a pretty reasonable proxy.
> > 
> > The vision that we'll all going to be carrying around a little security
> > fob (or at least a significant number of us) is probably a reasonable
> > approximation of a future truth.
> Yes.  If you really wanted to, you could do it now -
> http://www.ibutton.com/pki.html, or perhaps
> http://www.agatetech.com/products_q.html

One-time password fobs are already relatively common.  Friend of mine
working in public health was showing off his a few weeks back.

Karsten M. Self <kmself@ix.netcom.com>    http://kmself.home.netcom.com/
 What part of "Gestalt" don't you understand?       There is no K5 cabal
  http://gestalt-system.sourceforge.net/         http://www.kuro5hin.org
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