Re: Evaluation: draft-ietf-pkix-pi - Internet X.509 Public Key InfrastructurePermanent Identifier to Proposed Standard

[Leslie Daigle <leslie@thinkingcat.com>]

Hmmm, well, just to play devil's advocate for a second (and
because the alternative is that I have to back to playing
with powerpoint tables)...


Steven M. Bellovin wrote:
> In message <200304101701.NAA26528@ietf.org>, IESG Secretary writes:
>
> > Last Call to expire on: 2002-12-9
> >
> > 	Please return the full line with your position.
> >
> >                   Yes    No-Objection  Discuss *  Abstain  
> >
> > Steve Bellovin      [   ]     [   ]       [ X ]      [   ] 
>
> Permanent universally-unique names strike me as a singularly bad
> idea in general, and even worse as specified here.  A name can only
> be guaranteed to be unique (even in theory) within the scope of a
> single CA; there's no way to make any assumptions if different CAs
> are involved.  Sure, they're supposed to be URIs, but that's not
> enforceable except by referring to the parent certificate, and if
> you're going to do that why bother with a URI at all?  The notion
> of using permanent identifiers in ACLs is even worse.
Is it any more wrong than using, say, an e-mail address?  (Which
is unique at any given moment in time).  Then, each certificate
is a binding of:  a DN (which is more or less an "address" for
the cert, in some way), a public key, the PI-as-data (e-mail address) and
the CA's signature on that public key.  You can't trust this
binding any more than you trust the CA that signed it.

So, you shouldn't use PI's in ACLs, without the additional
enforcement of trusting the CA that signed the cert
(or else, as Ted pointed out when he & I were chatting on 
the phone) you can self-sign a certificate with the requisite
PI and in you go...

> Beyond that, the comparison rules for UTF8 strings look wrong --
> I'm glad there's a matching rule specified, but from the little I
> understand about such things there will be a lot of complaints
> about the lack of more CJK-friendly matching rules.
Actually, they should not -- because URIs, as currently
defined, are strictly a subset of 0-127 ascii.  If you
want anything else, you have to encode it (e.g., hex encoding).

Now, I'm not saying I think it's the best idea, and 
certainly there's something left to be desired in the
implementation proposal -- e.g., they haven't defined how an 
"Assignment Authority" should structure its strings such that there
won't be collisions across AA's in any given identifier
type.

Leslie.

--

-------------------------------------------------------------------
"Reality:
    Yours to discover."
                               -- ThinkingCat
Leslie Daigle
leslie@thinkingcat.com
-------------------------------------------------------------------