Subject: Re: Policy User Interfaces (was RE: Setting X.509 Policy Data in IE, IIS, Outlook)

From: [email-masked]
Date: Wed, 11 Feb 2004 10:04:24 +0000

> I would be interested to get a list of disadvantages of single-
> policy CAs.

From an owners persepctive, introducing additional CAs merely to
extend the number of available published policies represents an
unjustifiable increase in costs and infrastructure complexity
when the mechanism to support multiple policies per CA already
exists.

Chris

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From: "Anders Rundgren" <[email-masked]>
Date: Wed, 11 Feb 2004 14:30:32 +0100

Chris,

>From an owners perspective, introducing additional CAs merely to

You said what the other guys did not: "an owners perspective".

This is not exactly the same thing as parties involved in 
many-to-many PKI-secured communication comprising hundreds
or maybe thousands of uncoordinated PKIs, where some are TTPs
and others are in-house.

I claim that current PKIX standards poorly support such scenarios
as they have primarly been designed with "owners" in mind.

Anders

---

From: "Al Arsenault" <[email-masked]>
Date: Wed, 11 Feb 2004 09:28:07 -0500

> -----Original Message-----
> From: [email-masked]
> [mailto:[email-masked]]On Behalf Of Anders Rundgren
> Sent: Wednesday, February 11, 2004 8:31 AM
> To: [email-masked]
> Cc: [email-masked]
> Subject: Re: Policy User Interfaces (was RE: Setting X.509 Policy Data
> in IE, IIS, Outlook)
>

<snip>

> as they have primarly been designed with "owners" in mind.

Huh?  I'm lost.  "Many-to-many PKI-secured communication comprising hundreds
or may thousands of uncoordinate PKIs, where som are TTPs and others are
in-house."  What the heck is that supposed to mean?

I don't know what "uncoordinated PKIs" are supposed to be, but it sounds
like an inherently bad thing.  If they're not coordinated - which sounds to
me like there's not even a reasonable basis for cross-certification - then
why are they even trying to interact?  There's no basis for sound, reliable
communications.  "I got a signed message.  The signature appeared to
validate, but I have no idea who this person is.  The certificate was
claimed to be signed by CA_X, but I have no idea who CA_X is, or whether
they're authoritative for this person, or what their practices are, or ..."
Sounds to me like the signature is essentially useless.

To give a more concrete example (and apologies to the people I'm picking on,
but...) suppose I got a signed message promising me money from services,
from someone purporting to be "T. Chau" in Hong Kong. Suppose that his
certificate chained back to the "trusted root certificate" that comes along
with IE6 labeled "C&W HKT SecureNet CA Class A". Should I rely on that?
Why?

(And to make it more fun:  "C&W HKT" no longer exists as a company.  HKT was
"Hong Kong Telecom"; they were acquired several years ago by Cable &
Wireless; hence the "C&W".  Then that company was acquired in a leveraged
buyout by Pacific Century CyberWorks, or PCCW.  "SecureNet" was an
Australian company that recently got acquired by beTRUSTed.  (It would take
forever to explain that history.) "SecureNet Asia" was a joint venture in
the Hong Kong region between SecureNet (the Australian company) and PCCW,
and they competed with SecureNet on a number of projects. Parts of PCCW/HKT
were spun into a joint venture with Telstra called CSL, for "Create a Simple
Life" - really.)

So - should I rely on the signature/signed message, in the sense of relying
on it for something monetary? Why?  On what basis? Who owns this CA?  How is
it operated? What standards do they use?

That's my point - I'm hopelessly confused as to what you want here.  Do you
really want "many-to-many PKI-secured communication comprising hundreds or
may thousands of uncoordinate PKIs, where som are TTPs and others are
in-house?"

			Al Arsenault

---

From: "Anders Rundgren" <[email-masked]>
Date: Wed, 11 Feb 2004 16:49:05 +0100

Hi Al,

>> as they have primarily been designed with "owners" in mind.

>in-house."  What the heck is that supposed to mean?

OK, I'll give it a try.  In the current non-PKI enabled world we carry
out business using not perfectly secure methods such as snail-mail,
phones, e-mail and to some extent personal contacts.  A common
characteristic of these communication methods is that they require
negligible technical competence of the parties involved. 
The relations may be completely transient, to lasting a life-time.
The public generally do not perceive these systems as unreasonable
unsecure.  Callbacks and cross-checking is often performed in case
of doubts in a party's credibility. (why should PKI be any different?)

If we now as an experiment "dress this in PKI", how should it work?
According to your BBN-college Steve, TTPs are in no way
necessary which essentially means that each organization runs
their own CA.  Although Steve is probably a bit optimistic
regarding companies' desire running CAs, some big ones, and
some technology-savvy organizations will surely do that.  That
means indeed that the use-cases you describe below will happen
not once, but pretty often.

However, if this [general purpose communication] scenario requires
cross-certification and policy-mapping, I would say that PKI is toast,
and the venerable userid/password will just live on forever and ever.

Therefore I have suggested two(2) ways to make this scenario
more manageable:

1. Organizations should authenticate on the org (only) level.
   This dramatically reduces the number of "external" CAs needed
   as this level is much better handled by TTPs (in-house CAs who
   claim that "We are what we say we are" is IMHO ridiculous).

2. Improved ways to recognize and administer unknown (but single
    policy) CAs

Both of these proposals have been considerably bashed but the
arguments have IMO been pretty lame as most of the critics 
(unlike you) have not really tried to understand the scenario.

Your description is perfect.  You may indeed occasionally
have to "trust" something you don't know that much about.
Exactly as you do today.  There *will* be mistakes, but
even proper TTP CAs have problems with identity fraud.

But why should this "community" (=world) ever convert to PKI?
I believe that the main benefits would be:
- eliminating the distribution of shared secrets
- having a universal static ID towards all external parties

That is = cutting costs!

regards
Anders

Al's description:

Al Arsenault