Subject: Re: End-Entity Certificate Policies

From: Bill Burr <[email-masked]>
Date: Wed, 01 Sep 1999 14:33:01 -0400

Russ and Tim,

Wow, I'm somewhat in shock.  Limiting qualifiers to EE certs is probably a
good idea, but what problem does limiting EE certs to a single policy fix?
Comments in-line below:

At 04:56 PM 8/31/99 -0400, you wrote:
>Tim Polk and I got together today to discuss the changes needed to address 
>the policy mapping bug (as discussed at the Oslo meeting).  As part of this 
>discussion, we discussed the certificate policy extension.
>
>We believe that a CA certificate may contain one or more certificate policy 
>OID.  On the other hand, we believe that an end-entity certificate 
>containing a certificate policy extension must  contain a single 
>certificate policy OID.  

<SNIP>

>Does anyone disagree?

As you know, the Gov. of Canada, the US DoD and the US Federal PKI at
least, contemplate using policies for some sort of ordered "assurance
level."  The GOC defines four: rudimentary, low, medium and high.  I
believe that the assumption has been that anyone who would accept low would
also accept medium or high.  The straightforward way to handle this would
then be to put all four OIDs in high assurance certificates, medium, low
and rudimentary in medium assurance certificates, etc.  Your proposal seems
to break that.

The alternative is to make the relying party's initial set include all the
higher assurance level policies.  This seems cumbersome to me, and to move
the complexity to the client at run time, when we could handle it in the
certificates.     

Also, wouldn't it be useful to have separate OIDs in an EE cert for on-line
banking, stock trading, and other separable services that a single
financial institution might offer?  Do we want to force one bank or one
association to issued different certificates to the same person, for every
separate application?

What problem are we fixing here???

>
>Tim and I also discussed certificate policy qualifiers.  Tim and I agree 
>that certificate policy qualifiers should only appear in end-entity 
>certificates.  That is, we agree that certificate policy qualifier should 
>never appear in a CA certificate.  Does anyone (besides Mike Baum) disagree?

Good idea, as far as I can see.  If policy qualifiers have a use, it's
surely for EE certs.  Heaven forbid that every successive CA cert in a path
should cause a message to be displayed, or require a click acceptance.

>Russ
Regards,

Bill Burr

---

From: "Peter Williams" <[email-masked]>
Date: Wed, 1 Sep 1999 12:21:12 -0700

> should cause a message to be displayed, or require a click acceptance.

The particular processing you suggest for handling qualifiers in
critical policy extensions w/qualifiers should
be distinguished from the mere existence of
a qualifier value, in critical or non-critical policy
extensions.

If you check a VeriSign public intermediate CA using
the Windows UI interface, for example, it *offers*
you a button, which you *may* click, to chase
down the https URL built into the qualifier
of a non-critical policy extension, and learn
today's details of what reliance means, and determine
the warranted financial protections offered today. 
There is no downside to this design. There are many
upsides for PKIs addressing trade
and commerce whose activates are backed
by reinsurance. Removing it serves no purpose. It
has zero relevance to the cited bug fix, and
seems to reflect Russ' personal preference
to remove qualifiers from the face of the earth.

His preference was not reasonable during
2459 design, and is still not reasonable.
No particular military of US Federal assurance domain 
is required to use or accept them, however. Those 
other domains that do, accrue many benefits.

As the internet PKI is a collection of autonomous
domains, who can evidently interoperate using
PKIX rules, the current working infrastructure 
should continue.