Subject: RE: [TLS] Record layer corner cases

From: [email-masked] (Peter Gutmann)
Date: Wed, 29 Nov 2006 17:00:33 +1300

"Kemp, David P." <[email-masked]> writes:

>Apparently, the browser vendors referred to below have been busy tearing down
>and rebuilding.

More likely they never checked in the first place, and this just appears to
work by coincidence.  Perhaps we could ask the browser folks, a few of them
read this list: Did you consciously implement the X.509v4 changes to trust
anchor handling in your code within the last year or two?

Peter.

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From: "Kemp, David P." <[email-masked]>
Date: Wed, 29 Nov 2006 10:45:01 -0500

Or did they consciously implement the X.509v4 behavior before it was
documented in X.509v4 because they intuitively understood that it
was the right way to handle TAs?  And that the section on TA handling
wasn't just dreamed up by PKI fanciers divorced from reality, but was
added based on the expertise of, and problems encountered by, real
developers?

In a mesh PKI environment, one might want to establish trust anchors
at nodes where no self-issued certificates have ever been created and
where less than the entire content of a normal CA certificate is
appropriate across all RPs.  TAs deal with that fact by designating
name and key as the only essential information; all else goes in
the bin labeled "out of band".

I suppose a zillion monkeys might produce Shakespeare, but it's
highly improbable that computer code from multiple sources works
correctly by coincidence.  

Dave

-----Original Message-----
From: pgut001 [mailto:[email-masked]] 
Sent: Tuesday, November 28, 2006 11:01 PM
To: Kemp, David P.; [email-masked]
Cc: [email-masked]
Subject: RE: [TLS] Record layer corner cases

>Apparently, the browser vendors referred to below have been busy
tearing down

More likely they never checked in the first place, and this just appears
to
work by coincidence.  Perhaps we could ask the browser folks, a few of
them
read this list: Did you consciously implement the X.509v4 changes to
trust
anchor handling in your code within the last year or two?

Peter.

---

From: [email-masked] (Peter Gutmann)
Date: Thu, 30 Nov 2006 14:15:20 +1300

"Kemp, David P." <[email-masked]> writes:

>documented in X.509v4 because they intuitively understood that it was the
>right way to handle TAs?

OK, so they had some deep insight into ignoring dates in TAs even before it
was standardised in X.509v4.  Perhaps you could also explain the deep insight
they had that caused them to ignore basicConstraints (until widespread bad
publicity forced them to pay attention to it a year or two back), to ignore
keyUsage (this is even touted as a feature in some implementations), to
ignore... well, you get the picture.

>I suppose a zillion monkeys might produce Shakespeare, but it's highly
>improbable that computer code from multiple sources works correctly by
>coincidence.

You've got the analogy wrong.  The default behaviour for monkeys is to produce
gibberish.  The default behaviour for a minimal/least-effort/under-time-
pressure/whatever X.509 implementation is to check as little as possible, i.e.
to "process" certs in an oblivious manner.  So you need to say "I suppose a
zillion monkeys might produce gibberish" if you're going to use analogies with
X.509 implementations.

(As I noted before, I'd still like to hear from implementors if any of them
consciously made the change in X.509v4.  Send me private mail if you don't
want to go public with it).

Peter.