Re: [TLS] Certificate validation can of worms

[Watson Ladd <[e-mail]>]

On Fri, Apr 4, 2014 at 9:17 PM, Nico Williams <[e-mail]> wrote:
> On Apr 4, 2014 8:36 PM, "Watson Ladd" <[e-mail]> wrote:
>> 1: How will DANE make this worse?
>> 2: Is this really the best we can do? What features of X509 led to
>> these problems?
>
> Let's take #2 first.  Here's two entrants:
>
> - x.509 naming is impossibly difficult to deal with (see RFC4514);
>
> - stapled OCSP is how it should have been from day one -- CRLs add a ton of
> complexity

You are ignoring the reason we have CRLs in the first place: stapled
OCSP assumes all devices are globally connected and so can get OCSP.

Furthermore, neither naming nor OCSP/CRLs were involved in this
research, although the complexity may have lead to corners being cut
in the rest of the code.

> Back to #1:  DNSSEC is a PKI, but with better naming and fewer root CAs.
> We're going to need CT for DNSSEC.

Well, you're assuming that all implementations will agree on DNSSEC
validity. Even if they do, DANE connects to the X509 ecosystem. This
raises the problem of validating the parts between the TLS connection
and the link to DANE.

>
>> 3: This focused on server authentication. How does client authentication
>> fare?
>
> Very differently.  For user authentication I think something more like
> Persona (still PK, but not Internet-scale PKI) is better.  We really need a
> standard account & device enrollment protocol to make user PK work well --
> then we can land wherever on the PKI..web-of-trust..ad-hoc spectrum the
> market likes best.

Enrollment and accounts are secondary to making sure everyone agrees
on what a valid certificate looks like. If you don't have that, you
can't trust the results of authentication. This research analyzed
server certificates only. It didn't have user certificates to play
with. Furthermore, if X509 implementors  got this wrong, how do we get
it right?

Sincerely,
Watson Ladd

>
> Nico
> --



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