Subject: Re: Questions on Authority/Subject Key Identifiers

From: Stephen Kent <[email-masked]>
Date: Mon, 14 Oct 2002 11:09:07 -0400

At 5:52 PM +1200 9/29/02, Peter Gutmann wrote:
>Stephen Kent <[email-masked]> writes:
>
>>The real world issue you describe calls for re-issuance of certs; it does not
>>justify violating the standards.
>
>In *theory* it calls for the re-issuance of certs.  I can quite easily see
>that the practical approach would be to chain by sKID, and obviously enough
>people agree with this that they persuaded MS to change the behaviour of their
>code to allow it (the issue you're referring to was a bug, not a deliberate
>design decision like sKID chaining).
>
>Peter.

peter,

With much MS code, it's hard to tell the difference between bugs and 
design errors, er, I mean features :-)

The BasicConstraints "feature" in path validation is just the latest 
example. Nobody from  MS ever brought this suggestion up on PKIX or 
argued to have the PKIX docs accommodate this processing approach 
based on ANY arguments. So, I have no basis to believe that customers 
asked MS to make their software work in this fashion, vs. someone in 
MS just deciding that this was just a good idea.  Given that context, 
it is hard for me to be sympathetic to this violation of the 
standards.

Consistent with the SKID/AKID matching model, I have been told that 
the MS code also searches for certs based on the SKID, which is a 
non-scaleable approach given that there is no general way to loacte a 
cert based on this value. It is more efficient in a closed 
environment, but we prize Internet standards that work in open 
environments, not ones optimized for closed environments.

Yes, it would simplify life for a company that was rehomed under a 
new cert, but as an employee of a company that changed parent names 
twice in a 3 years period, I don't see reissuance of certs as a 
terrible burden. Employees of BBN got to change business cards and 
stationary as well as company signs, web site content etc. when we 
became part of GTE, and then GTE merged with Bell Atlantic to become 
Verizon.  Cert reissunace is just another task and not my any means 
the most expensive one under these circumstances.

Steve

---

From: Michael Ströder <[email-masked]>
Date: Mon, 14 Oct 2002 19:25:32 +0200

> design errors, er, I mean features :-)

Disclaimer: I'm not related to MS nor do I want to defend MS in general.

> example.

This is a very good example: I guess some programmer was trying "to make it 
work". I can imagine that the developer had quite a bunch of examples of 
malformed certs of well-known CAs and decided to not take care of 
BasicConstraints because some of the famous CAs designed by so-called PKI 
experts are simply flawed.

IMHO this particular discussion and other threads like "Identifying the 
right CRL for a given certificate" show that some very basic issues are not 
made clear enough.

Several times I mentioned that I suspect PKIX is getting far too complex to 
be ever implemented correctly. Folks here always forget that for a developer 
making an application "PKI-enabled" is a side-job. Still lots of new 
"features" are pushed through the IETF-PKIX without caring about how to 
implement them correctly.

Having said this I wonder why people consider cross-certification, bridge 
CAs and such. IMHO these things just open other cans of worms and give 
developers a hell of a time...

Ciao, Michael.