[cabfpub] [cabfman] Improving the security of EV Certificates

Ryan Sleevi sleevi at google.com
Wed Dec 18 18:11:14 UTC 2013

Hi Eddy,

Thanks for allowing this to be posted to the public list. I've attempted to
reply to your points below.

On Wed, Dec 18, 2013 at 9:55 AM, Eddy Nigg (StartCom Ltd.) <
eddy_nigg at startcom.org> wrote:

> On 12/18/2013 07:28 PM, From Jeremy Rowley:
>  Pinning is more risky for unsophisticated users who could brick their
> systems.
> I don't think so....such users would never use it, the same way such users
> would never investigate a log or list of certificates.

>   Plus, pinning becomes a market divider so I’d worry about anti-trust
> violations if the recommendation came from the CAB Forum.
> How come, can you explain?

Much in the same way that some CAs object to CAA. Any notion of having the
CA/Browser Forum encourage that users use technological means to say "I
have relationships with these CAs, and I would prefer [other CAs] not
issue" seems to scare some members. I do not believe this is at all
warranted, and is more likely a mischaracterization of the technology, but
that's something to be deferred for your own legal counsel.

Both pinning and CAA are ways for customers to take control of the "Every
CA is capable of issuing for every site" issue, which we see year after
year, incident after incident to be the root cause of the continued erosion
of trust in the CA ecosystem.

>   Transparency, in my view, is better because it requires a change only
> by the CAs and browsers, not by the users.  The information is then
> available for any researcher to digest and evaluate, not just the end user.
> It's mostly the competing CAs!!!, software vendors, Netcraft and friends,
> and some researchers that care about it (EFF, Qualsys and some others).
> It's the same crowd that would use pinning too.

This is not true at all.

Auditors are not equivalent to site operators. Site operators carry great
risk in pinning and getting it right - it certainly provides preventative
benefits, but with an operational complexity cost. Further, organizations
like EFF, Qualsys and others cannot defer those costs on behalf of the site
operator. It's a risk they bear on themselves.

Pinning offers the ability for anyone, without risk to their operational
capability, to look to examine for misissuance - past or present. This
presents zero risk for the site operator, at a cost born by the CA, whereas
today's system of global issuance capability with no auditing is a
zero-cost-to-the-CA, with risk and cost born by every single site that
would ever wish or does use SSL.

>   A headache is when another DigiNotar is compromised , issues a couple
> thousand certificates fraudulently, and covers it up for several months.
> Truly a problem, but may be attacked from a different angel (how about
> different approach  to auditing?). I mean, we are doing our utmost to
> comply to all the various requirements and much more than that - a price we
> are willing  to pay because for this we are here. Now this proposal has a
> significant price tag for something that hasn't been tested and used over
> time with the "only" goal to detect the next DigiNotar.

Every single public CA security incident we have seen in the past 3 years
would have been detected immediately from a system like CT. Trustwave,
Diginotar, Turktrust, and most recently, ANSSI were all detected through
luck and vigilance, and only because they happened to affect a large site
whose engineers are using every means capable to them to attempt to detect
such mis-issuance.

For all we know, there may be thousands of other misissuances from existing
CAs - whether well-meaning or not - that have gone unnoticed, simply
because they did not decide to affect one particular site. CT makes it
possible for anyone - from Joe Schmo on the street with his $10
certificate, to the multi-billion dollar multi-national with engineers
committed to dealing with just this issue - to detect misissuance.

I think you're pretty grossly understating the benefit here.

> IMO pinning can achieve the same way cheaper (for me). And again, if we
> could combine revocation for example, the benefit would be much bigger and
> trade off the expenses/efforts...

Assume the cost of pinning is $100/year/site.
Assume the cost of CT is $10,000/year/CA.

By any measure, CT has a far bigger benefit with far fewer expenses,
efforts. And that's using a very generous understatement of pinning's costs
(operationally), which is likely several orders of magnitude higher as the
profile of the site increases. And even if CT itself carries with it
several orders of magnitude more cost, the math *still* works out, because
there are *millions* of sites that use SSL, and *millions* more that
should, and if your idea is pinning is right for everyone, then you're
asking inordinate amount of costs to be born for all users, many of which
who may and are happy with "detection" over "prevention" for their
risk/reward profile.

>   Regards      Signer:  Eddy Nigg, COO/CTO    StartCom Ltd.<http://www.startcom.org>
> XMPP:  startcom at startcom.org  Blog:  Join the Revolution!<http://blog.startcom.org>
> Twitter:  Follow Me <http://twitter.com/eddy_nigg>
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