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

From: "Denis Pinkas" <[email-masked]>
Date: Thu, 4 Aug 2005 10:57:36 +0100

>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.

Matching the CRL certification path with that of the target certificate is certainly secure.
However, after some discussions with some PKIX members, it appears that is can be made 
more general without loosing any security.

If the same TA is used and the same sequence of CA DNs (below that TA) is used, 
then it is always secure.

Now if the RP locally "knows" some additional naming rules that apply to every CA below 
each trusted TA from the validation policy that is being used, then this rule may not
be necessary.

Denis

>-----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: Thu, 4 Aug 2005 06:51:15 -0400

Denis,

Thanks for agreeing that RFC for my approach is simple and the approach is
not complex (You capture the rules in 2 sentences below).

Now, for the alternative as to what the relying party knows about each PKI,
what would you say in an RFC?  Please provide specific words.

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On
Behalf Of Denis Pinkas
Sent: Thursday, August 04, 2005 5:58 AM
To: 'pkix'; Santosh Chokhani
Subject: Re: 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.
>

Matching the CRL certification path with that of the target certificate is
certainly secure. However, after some discussions with some PKIX members, it
appears that is can be made 
more general without loosing any security.

If the same TA is used and the same sequence of CA DNs (below that TA) is
used, 
then it is always secure.

Now if the RP locally "knows" some additional naming rules that apply to
every CA below 
each trusted TA from the validation policy that is being used, then this
rule may not be necessary.

Denis

>From: [email-masked] 
>[mailto:[email-masked]] On Behalf Of Tom Gindin

Regards,

Denis Pinkas