Subject: Re: PGP Keyserver Synchronization Protocol

From: "William H. Geiger III" <[email-masked]>
Date: Thu, 01 Jul 1999 09:27:28 -0500

In <[email-masked]>, on 07/01/99 
   at 12:54 AM, Marcel Waldvogel <[email-masked]> said:

>William,

>this was said thinking about duplicate signatures or revocation
>certificates or other stuff:

>- Many key owners seem to revoke their keys more than once, so many
>  keys on different servers have different revocation certificates.
>  (Importing Peter Wan's keyring into my database gives some hundred of
>  these).
>- Many users sign the same UserID more than once. The current pksd
>  prunes them to all but one. Currently, pksd does this by taking the one
>  with the newest time stamp. Other keyservers may have a different
>policy. - If keyservers are put into place which really check the
>validity of the
>  revocations/signatures before either adding them or allowing them to
>  replace other revocations or signatures, there may be even more
>differences.

>Unless all keyservers follow exactly the same policies and these policies
>do not depend on the order in which the PGP packets are received, the
>number of unresolved or unresolvable differences will increase. And I am
>not really sure which policy is the "right" one.

I was not aware that this was going on but it is something that, IMHO,
*must* be addressed. This issue not only affects the key servers but also
the users keyrings. I don't like the idea of the servers making these
types of determinations if they are not doing any verification of the
signatures. It opens up a DOS attack on a key by replacing the self
signature with an invalid signature of a newer date. To be honest I don't
like the idea of the public servers removing anything from an existing
key. It opens up problems that the servers are not in a position to
address.

-- 
---------------------------------------------------------------
William H. Geiger III  http://www.openpgp.net
Geiger Consulting    Cooking With Warp 4.0

Author of E-Secure - PGP Front End for MR/2 Ice
PGP & MR/2 the only way for secure e-mail.
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Hi Jeff!! :)
---------------------------------------------------------------

---

From: Marcel Waldvogel <[email-masked]>
Date: Fri, 2 Jul 1999 11:02:09 +0200

> key. It opens up problems that the servers are not in a position to

Both strategies, either keeping the first (revocation) signature or
updating them, is open to DoS. I would prefer the keyservers to keep
(and return) all duplicate (revocation) signatures, but only display
one of them. Then the user's OpenPGP implementation should deal with
it. Duplicate signatures shouldn't break anything, but I would like
to know whether anyone assumes that duplicate revocations might break
something?

-Marcel

---

From: Patrick Feisthammel <[email-masked]>
Date: Fri, 2 Jul 1999 13:13:44 +0200 (CEST)

-----BEGIN PGP SIGNED MESSAGE-----

Hi!

> to know whether anyone assumes that duplicate revocations might break

I do not think they break something. OpenPGP implementation should handle
multiple signatures with similar meaning. 

If there are implementations which have different behaviour according to
the additional information of the signature, they can have problems.
Such additional informations are the creation time of the signature (an
implementation could treat signatures valid if they occured befor the
revocation of the key) or the reason for the revocation (if the reason is
a changed userID the OpenPGP implementation could take signatures for 
valid, but not if the reason is a compromised key).

IMHO the keyservers should store all key information and not try to guess
what part of this information an application needs to work. 

Cheers,
Patrick

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