Subject: RE: Open Issue in Part1: path length constraints

From: David Kemp <[email-masked]>
Date: Tue, 6 Mar 2001 11:25:07 -0500 (EST)

Al,

The question is what should be done about language such as RFC-2459
section 5.1.2.5:  "This profile requires inclusion of <xxx> in all CRLs
issued by conforming CAs."  In the case of CRLs signed by an end
entity, I wouldn't want anyone to think that "This profile does not
require inclusion of <xxx> in all CRLs issued by conforming end
entities". :-)

I'm quite happy with Warwick's "issued by conforming CRL Issuers".
And I see you can accept that too.

But to return to the original question: should path length constraints
yield the identical results when the CRL Issuer is a CA and when the
CRL Issuer is an end entity?   I say yes - a CRL should be accepted
in one case iff it is accepted in the other case.

Dave

P.S. There is a difference between OCSP and CRLs - OCSP responses
can be signed by a "trusted" responder (one which is not operated
by the Certificate Management Authority, to use the DoD's term
for the CA and it's authorized agents.)   CRLs, on the other hand,
are never valid unless signed by the CA or the CA's designee.
For that reason, I think it's reasonable to talk about CRLs being
issued by the CA even when basicConstraints is absent in the CRL-signing
cert.  But "CRL Issuer" says it all, so there is no reason pursue
whether a CRL signed by the CA's agent is "issued" by the CA.

> From: "Al Arsenault" <[email-masked]>
>
> I would support the former, or some variant of it.  Let's be clear about 
> our terminology.  We don't call an entity which signs OCSP responses but 
> doesn't sign certificates and has basicConstraints absent a "CA".  We 
> shouldn't call an entity which signs CRLs but doesn't sign certificates and 
> has basicConstraints absent a "CA", either.
> 
> If we're sloppy with the terminology, somebody later on is going to fail to 
> grasp the subtlety of it and get this wrong.

---

From: David Simonetti <[email-masked]>
Date: Tue, 06 Mar 2001 13:38:11 -0500

Dave,

I agree with you on both points.

Dave S.

--
David Simonetti
Securify (www.securify.com), 410-356-2260

---

From: "Michael Myers" <[email-masked]>
Date: Tue, 6 Mar 2001 13:31:06 -0800

> From: David Kemp [[email-masked]]
> Sent: Tuesday, March 06, 2001 8:25 AM
> To: [email-masked]
> Subject: RE: Open Issue in Part1: path length constraints
>
> . . .
>
> can be signed by a "trusted" responder . . . . CRLs, on the other hand,
> . . .

Dave,

Does your observation of a "trusted" responder interpret case 1.b below or
were you intending to speak to some broader notion?

Section 4.2.2.2 of RFC 2560 asserts the following normative requirements:

   "Systems or applications that rely on OCSP responses . . . MUST reject
   the response if the certificate required to validate the signature on
   the response fails to meet at least one of the following criteria:

   "1. Matches a local configuration of OCSP signing authority for the
   certificate in question; or

   2. Is the certificate of the CA that issued the certificate in
   question; or

   3. Includes a value of id-ad-ocspSigning in an ExtendedKeyUsage
   extension and is issued by the CA that issued the certificate in
   question."

The generality of case 1 allows for two sub-cases:

   1.a  An implicitly trusted but nonetheless CA-delegated trusted
   public key; and

   1.b  A key that is implicitly trusted by a relying party but is
   in no way related to the issuer of the certificate in question.

Mike