Subject: RE: WG Last Call: Permanent Identifier

From: "Manger, James H" <[email-masked]>
Date: Tue, 4 Jun 2002 12:01:46 +1000

I suspect the consequences of issuer name clashes are not so different for
perm. id and CRLs.  The clash will appear to a relying party as a separate
key (different key id) for the same CA.
The relying party will happily accept a CRL signed with CA1's key2 as a
proper CRL for a cert signed with CA1's key1.  Similarly a relying party
will happily compare a perm. id signed by CA1's key2 with a perm. id signed
by CA1's key1.

In both cases the system fails for the same reason when the two keys belong
to different CAs with the same name "CA1".

I agree with Russ' suggestion to add ~ "The CA is unambiguously identified
by the distinguished name in the issuer field." to explicitly state the
documents assumption.

P.S. I much prefer "unambiguous" to "unique" were appropriate.  It is often
unclear whether "unique" means only one entity is identified or an entity
has only one of these identifiers.

> ----------
> From:	Housley, Russ [SMTP:[email-masked]]
> Sent:	Tuesday, 4 June 2002 4:58 am
	...
> As Tom already pointed out, we expect the issuer field to uniquely
> identify 
> the CA.  CRLs and CMS both rely on this feature.  So, I think you should
> say:
> 
>     If identifierType is missing, then the permanent identifier is
>     locally unique to the CA.  The CA is uniquely identified by the
>     distinguished name in the issuer field.
> 
> Then, I think that you should include a paragraph in the security 
> considerations that tell what the consequences are if the issuer 
> distinguished name is not unique.  I belive that that they are different 
> than the CRL.  With the CRL, the CRL signature will not check if the
> public 
> key associated with the second CA with the same distinguished name is
> used.
>

---

From: "Housley, Russ" <[email-masked]>
Date: Tue, 04 Jun 2002 08:26:47 -0400

James:

When a CA uses the same private key to sign certificates and CRLs, which is 
the common practice today, then a mismatch will be apparent.  However, as 
you correctly observe, the mismatch is not apparent if different private 
keys are used to sign certificates and CRLs.  This can happen by design or 
it can happen during key rollover, not just when there is a name collision.

I still think that the consequences of name collision should be described 
in the security considerations section.

Russ

---

From: Denis Pinkas <[email-masked]>
Date: Thu, 13 Jun 2002 16:29:51 +0200

To the co-chairs and to the list,

During the last call period on the Permannet Identifier draft, comments 
from Russ Housley have been received. The co-editors have taken into
consideration these comments. 

Russ Housley received a private copy and has confirmed that all issues he
posted to the mail list have been addressed.

The revised draft has been placed on the IETF server and is available from:
http://www.ietf.org/internet-drafts/draft-ietf-pkix-pi-04.txt

Denis