Subject: Re: RE: 3280bis: suggested words for ambiguous DNs and delegated CRLs

From: "Denis Pinkas" <[email-masked]>
Date: Fri, 5 Aug 2005 12:50:14 +0100

>Tom,

>That would be fine for indirect CRL.  

This is insufficient, unless additional naming constrains are localy known.

> I assume you are not recommending this
>for a direct CRL (i.e., when Cert Issuer = CRL issuer)

>-----Original Message-----
>From: Tom Gindin [mailto:[email-masked]] 
>Sent: Thursday, August 04, 2005 9:38 AM
>To: Santosh Chokhani
>Cc: 'pkix'
>Subject: RE: 3280bis: suggested words for ambiguous DNs and delegated CRLs
>
>        Santosh:
>
>        Actually, I have been arguing for requiring the CRL issuer's 
>certification path to be a subset of the subject certificate's path.  I 

Unless additional naming constrains are localy known, this may be insecure.

Denis

>don't see any major issue if the hierarchical superior of a CA issues a 
>CRL signing certificate which can issue CRL's for the subordinate CA's. 
>However, I don't see how to go beyond that.
>
>Tom Gindin

>"Santosh Chokhani" <[email-masked]>
>Sent by: [email-masked]
>08/03/2005 10:17 AM
> 
>        To:     "'pkix'" <[email-masked]>
>        cc: 
>        Subject:        RE: 3280bis: suggested words for ambiguous DNs and 
>delegated CRLs
>
>
>
>Tom Gindin,
>
>You seem to be arguing for matching CRL certification path with that of 
>the
>certificate.
>
>If so, you will not get an argument from me.
>
>-----Original Message-----
>From: [email-masked] [mailto:[email-masked]] 
>On
>Behalf Of Tom Gindin
>Sent: Tuesday, August 02, 2005 11:17 PM
>To: Manger, James H; [email-masked]
>Cc: pkix
>Subject: RE: 3280bis: suggested words for ambiguous DNs and delegated CRLs
>
>
>
>        James, Santosh:
>
>        You certainly can construct unambiguous names for CA's, and I 
>think that Denis already knows that (Permanent Identifier is certainly a 
>way of constructing unambiguous names, for example).  The difficulty we 
>have is when one issuer issues a certificate to an organizational CA with 
>a subject name which is convenient and in common use for its organization, 
>
>but ambiguous, and then a different issuer issues a certificate to an 
>organizational CA with the same subject name which is also in common use 
>for its organization.  This case is most common when both organizations 
>use an acronym.  I do not see why the issuers of the two organizational CA 
>
>certificates should be assumed to originate at different trust anchors, 
>although they will be different issuers.  In fact, I don't understand why 
>organizational name collisions are thought to be much rarer with a "common 
>
>trust anchor" than with "different trust anchors" if the actual issuers of 
>
>the colliding certificates are both public CA's.
>        Such collisions will have negative effects in other parts of the 
>global PKI, of course.  However, unless we are prepared to issue guidance 
>to deprecate the assignment of DN's for organizations with geographical 
>scopes wider than the one for which they are registered and guaranteed to 
>be unique (and many existing CA certificates have such DN's), I don't see 
>how we can be certain or nearly certain that such collisions won't occur. 
>A typical example of what I mean by an organization having a DN with a 
>geographical scope wider than the one for which it's registered is a 
>corporation registered in a single American state and operating in several 
>
>states while having a DN without the stateOrProvinceName attribute.
>
>                Tom Gindin
>
>
>
>
>
>
>"Manger, James H" <[email-masked]>
>Sent by: [email-masked]
>08/01/2005 11:05 PM
> 
>        To:     "pkix" <[email-masked]>
>        cc: 
>        Subject:        RE: 3280bis: suggested words for ambiguous DNs and 
>
>delegated CRLs
>
>
>[Santosh: Requiring a unique DNS may be fine.  But, CA does not know the 
>trust anchors environment of the relying parties to know if the CRL issuer 
>
>DN will be unambiguous.]
>You can construct unambiguous DNs regardless of trust anchors.  For 
>instance, including DC components can make a DN as unambiguous as a DNS 
>name.  As another example, the following DN
>  o=?Qantas Airways Limited, ABN 16 009 661 901?, c=?AU?
>is unambiguous as it lists a registered business name, its Australian 
>Business Number (ABN) and the jurisdiction where those are unambiguous 
>(Australia).  It is inconceivable that any CA could issue such a DN to 
>another entity in good faith.
>The DN cn=?John Smith?, c=?US? may be unambiguous in the context of an 
>issuing CA, but would be ambiguous in a wider context so it should not be 
>used in cRLIssuer ? use rfc822Name=?[email-masked]? instead, for 
>instance.
>
>
>
>
>

Regards,

Denis Pinkas

---

From: "Santosh Chokhani" <[email-masked]>
Date: Fri, 5 Aug 2005 08:45:27 -0400

Denis,

I agree that the rule of an ancestor may not be sufficient (specially
theoretically).  An alternative is to permit only the following:

1.  Indirect CRL is signed using the same trust anchor DN as the certificate
certification path; or

2.  Indirect CRL is signed using an authority that is issued a certificate
by the same trust anchor DN as the certificate certification path; or

3.  Certificate issuer CA delegates the Indirect CRL issuer.  In this case,
depending on the reason for indirect CRL, the revocation status of the
delegation certificate may need to contain no check or verified using
partitioned CRL.

The implementations I know that use Indirect CRL are consistent with the
above.  But, it a further constraint/profiling/change to the Standard.

BTW, what are the examples of "locally known constraints" and/or how would
you articulate these in an RFC?

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On
Behalf Of Denis Pinkas
Sent: Friday, August 05, 2005 7:50 AM
To: 'pkix'; Santosh Chokhani
Subject: Re: RE: 3280bis: suggested words for ambiguous DNs and delegated
CRLs

Denis

Regards,

Denis Pinkas