Subject: RE: Cross-certification

From: "Alberti Antoine" <[email-masked]>
Date: Thu, 1 Jul 2004 11:29:45 +0200

Thanks for the answers. Wouldn't this issue diserve a little bit of a specification ? For instance, I understand cross-certification when an authority has several certificate with the same public key and the same subjectDN, but the second document Craig Borysowich indicated gives an example of an authority that has several public keys. I suppose this is a consequence of a key renewal (is it really the only case ?). But then, the cross-certification is not valid anymore, is it ? I assume certifying means signing a public key, but I may be wrong.

-----Message d'origine-----
De : Borysowich, Craig (CSS) [mailto:[email-masked]]
Envoyé : mercredi 30 juin 2004 20:15
À : Alberti Antoine
Objet : RE: Cross-certification

http://www.au-kbc.org/bpmain1/PKI/cross_certification.pdf
 
http://www.geminisecurity.com/docs/ndss050.doc
 
These papers may give you some insight...

-----Original Message-----
From: Alberti Antoine [mailto:[email-masked]]
Sent: Wednesday, June 30, 2004 11:16 AM
To: [email-masked]
Subject: Cross-certification

Would there be any document where cross-certification and non-hierarchical infrastructures are defined, please ? 
Regards. 

	        Antoine Alberti                 Axway.  a Sopra Group company   
        Tel  : +33 (0)1 47 17 24 37             XFB R&D 
        Fax : +33 (0)1 47 17 24 25              26 Rue des Pavillons 
        email: [email-masked]               92807 Puteaux Cedex - France

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From: "Anders Rundgren" <[email-masked]>
Date: Thu, 1 Jul 2004 15:06:44 +0200

Cross-certificationAntoine,

Although slightly off-topic, may I add that cross-certification is unlikely to ever be a main-stream activity as neither commercial CAs or private enterprises having many partners feel any particular need or interest in these schemes that are based on the same intellectual foundation as public LDAP directories.  You may be interested to hear that governments in Scandinavia have found a much more useful way to communicate and that is using domain-based security.  This reduces the number of external CA certificates and keys to an absolute minimum.

Anders Rundgren

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From: Jean-Marc Desperrier <[email-masked]>
Date: Thu, 01 Jul 2004 18:47:18 +0200

Alberti Antoine wrote:

> [...] the second document Craig Borysowich indicated gives an example 
> of an authority that has several public keys. I suppose this is a 
> consequence of a key renewal (is it really the only case ?). But then, 
> the cross-certification is not valid anymore, is it ? I assume 
> certifying means signing a public key, but I may be wrong.

The CA should get a cross-certificate for it's new key to simplify the case.
It's up to proper implementation of path validation to correctly handle 
the fact the CA has several different key/certificate, and to be able 
select the correct path.

But according to RFC2510 (&2.4.1), it is not strictly required to get a 
new cross-certificate.
When getting a certificate for it's new key, the CA should generate a 
"old with new" and a "new with old" certificate, and the path validation 
should be able to switch from one of the key to the other by following 
here what we could call a mono-entity cross-certification.

This said it will change the length of the path, which can break the 
verification depending on the constraints, so it is much better to get 
one cross-certificate per key.

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From: Jean-Marc Desperrier <[email-masked]>
Date: Thu, 01 Jul 2004 19:07:38 +0200

Anders Rundgren wrote:

> Although slightly off-topic, may I add that cross-certification is 
> unlikely to ever be a main-stream activity as neither commercial CAs 
> or private enterprises having many partners feel any particular need 
> or interest in these schemes

There was a presentation by a member of the Asia PKI Forum in the ETSI 
security plugtests, that showed they were concretely interested in 
getting this to work to enable inter country level exchange in Asia.
That would cover exchange between China; Hong Kong, Japan, South Korea, 
Singapore, etc...

Also if one is interesting in checking how cross-certification can work 
concretely the best place is certainly to go check all the US Federal 
Bridge Certification Authority  related links.
http://csrc.nist.gov/pki/fbca/welcome.html

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From: "Anders Rundgren" <[email-masked]>
Date: Thu, 1 Jul 2004 22:50:32 +0200

Sure J-M,
But note, I explicitely mentioned private enterprises and
commercial CAs as no likely targets for cross-cert.

Regarding ETSI, PKI-forum etc.

All these places lack an "informaton model", they believe
that security = cryptography and trustworty CAs.  Security
in an organizational environment has other dimensions
that the end-to-end model can't support.  Not a single paper
has been written explaining how archiving, authorization
privacy, etc. is supposed to be handled in a true end-to-end model.
Which is sort of understandable as it is technically infeasible.

It was amusing to read on the S/MIME list, Phill H-B claim
that this (e2e) model have made us stuck for ten years in the
same place.  But as I said, in Scandinavia and in Estonia
we have given up this model and I believe for good.

There is a reason....

Wrong! There are *numerous* reasons.

A simple one is that I used to buy computers from DELL, not 
from Michael Dell.  And DELL knows me as a company account
with Anders Rundgren as contact person.  One of them.

Anders

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From: Michael Ströder <[email-masked]>
Date: Fri, 02 Jul 2004 09:14:44 +0200

Jean-Marc Desperrier wrote:
> getting this to work to

Watching PPT slides showing that someone is "interested in" something is 
completely different from having it already in production in a reasonable 
big deployment.

=> I don't buy that.

Ciao, Michael.