Subject: Re: Holder (was Re: Comments on draft-ietf-pkix-ac509prof-05.txt)

From: "David P. Kemp" <[email-masked]>
Date: Mon, 6 Nov 2000 10:28:24 -0500 (EST)

> From: Polar Humenn <[email-masked]>
> 
> Dave,
> 
> I like your summary below and I agree with it.
> 
> Question, would a suggestion adding that AA's SHOULD generate one of the
> 4,8,1,3,5,7,9,11 that they support instead of 2.
> 
> Note that statement would only apply to where Public Key Certificates are
> the link to the holder.
> 
> Cheers,
> -Polar

When PKCs are used, option 2 means that the holder is not a specific
PKC, it is any PKC used by the named entity.  I believe that being able
to preserve attribute links when PKCs are rekeyed (or allowing a
subject to authenticate using his choice of PKCs) is a requirement, so
I don't support saying that AAs SHOULD use one of 4,8,1,3,5,7,9,11
instead of 2.   The profile should not say "*every* AA SHOULD avoid a
useful option because *some* people trust 137 roots."

> From: Steve Hanna <[email-masked]>
> 
> So I suggest again that there's little reason to use formats 5, 7, and
> 9. If the holder is a PKC, include all the available hints by using
> format 11.

BaseCertificateID (7 or 11) allows you to match without hashing
every candidate, but that is a pretty minor benefit.  Being able to
search by issuer might be useful, although it doesn't seem to be widely
supported now.  The case against 11 (extra bulk in every AC) is pretty
weak, but it might be important in low-bandwidth applications.  The
question boils down to "Do we know enough to recommend that every AC
include information that is 'rarely' useful but could be 'slightly'
harmful?"

I don't have a dog in this race, so I don't have a strong preference
for 9 only, 11 only, or all of 5,7,9,11.  As long as the profile
doesn't prohibit ACs using any of the 11 formats (by saying AAs MUST
use some subset), I'm happy.

---

From: Steve Hanna <[email-masked]>
Date: Mon, 06 Nov 2000 14:39:25 -0500

> useful option because *some* people trust 137 roots."

Yes. If you trust your PKI to securely map a name to a public key, then
it's perfectly appropriate to use format 2 in conjunction with a PKC. If
you don't trust your PKI, then you should probably use a format based on
the hash of the public key.

> use some subset), I'm happy.

I also don't have a "dog in this race" (if by that you mean a product or
business that depends on the use of one of these formats). My main goal
is to increase interoperability. For this reason, I would like to see us
settle on a small number of formats that AC verifiers and issuers SHOULD
be able to verify and issue. Certainly, they MAY use any of the formats,
depending on their needs.

Are there low-bandwidth AC applications in the Internet domain? At
least, ones where 30 more bytes per AC would be likely to cause a
problem? If so, could someone provide an example?

-Steve