Subject: RE: CONSENSUS CALL: KDC certs part 1

From: "Liqiang(Larry) Zhu" <[email-masked]>
Date: Wed, 31 Aug 2005 12:45:58 -0700

RFC3280 says name constraint is not defined for "otherName"

-----Original Message-----
From: Nicolas Williams [mailto:[email-masked]] 
Sent: Tuesday, August 30, 2005 11:15 PM
To: Jeffrey Hutzelman
Cc: Stefan Santesson; Liqiang(Larry) Zhu; Paul Leach; Sam Hartman;
[email-masked]; [email-masked]
Subject: Re: CONSENSUS CALL: KDC certs part 1

On Wed, Aug 31, 2005 at 12:33:25AM -0400, Jeffrey Hutzelman wrote:
> 
> 
> On Tuesday, August 30, 2005 23:10:54 -0500 Nicolas Williams 
> <[email-masked]> wrote:
> 
> >On Tue, Aug 30, 2005 at 11:31:53AM +0100, Stefan Santesson wrote:
> >>I have no problem with this approach in principle.
> >>
> >>However, I have a little problem with "SHOULD use name constraints"
> >>
> >>Name constraints is a protective measure by a CA and not by a
client.
> >>The client MUST "use" any name constraints present in the validated
> >>path. A CA however only applies name constraints when it is relevant
> >>(When it does not fully control or trust cross certified CAs)
> >
> >PKINIT is a very special PKI application though.  I think the client
> >really does want to apply/verify name constraints in the cert chain
of a
> >KDC cert because the KDC cert is a like a CA cert and the client has
to
> >talk the KDC.  Otherwise PKINIT clients will need more configuration,
in
> >a large PKI, than just trust anchors.
> 
> I'm afraid you're not making any sense.  The question of whether to
pay 
> attention to name constraints is not up to us, or to the PKINIT
client. 
> The name constraints extension MUST be critical, and verifiers MUST
check 
> them.  These requirements come from RFC3280.

I misread something Stefan wrote.  But we still have the problem that we
either can't apply name constraints to id-pksan or we have to explain
how.  Looking at RFC3280 it does seem like we could specify how to apply
name constraints to id-pksan.

---

From: Jeffrey Hutzelman <[email-masked]>
Date: Wed, 31 Aug 2005 16:50:12 -0400

> RFC3280 says name constraint is not defined for "otherName"

No, RFC3280 says that RFC3280 does not define how to process name 
constraints for otherName.  It does not preclude some other document from 
doing so.

---

From: Nicolas Williams <[email-masked]>
Date: Wed, 31 Aug 2005 20:18:18 -0500

Nico> I misread something Stefan wrote.  But we still have the problem
Nico> that we either can't apply name constraints to id-pksan or we have
Nico> to explain how.  Looking at RFC3280 it does seem like we could
Nico> specify how to apply name constraints to id-pksan.

Larry> RFC3280 says name constraint is not defined for "otherName"

Stefan pointed this out, I agreed, then I suggested that we could
furnish that definition for the KRB5Principal AnotherName.

I don't see where RFC3280 says you can't -- it's wording even
suggests that yes we can ("...are not defined by this specification"
-- leaving it to one or more other specs, say).  If we can't it must
be for some subtle reason, like perhaps some implementations won't
know what to do with name constrainst of AnotherName and fail
certificate verification.

Nico
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