[cabfpub] Ballot 184: rfc822Names and otherNames

Ryan Sleevi sleevi at google.com
Fri Jan 6 02:03:24 UTC 2017

On Thu, Jan 5, 2017 at 5:43 PM, Jeremy Rowley <jeremy.rowley at digicert.com>

> If the WFA want to use the Web PKI, well, then I'd encourage them to
> participate in the Web PKI discussions - which, unfortunately, is largely
> gated on GovReform.
> [JR] This discussion, right now, is essentially the WFA participating in
> the Web PKI discussions.

Then are you the person to direct all the hatred at the stupidity of the
OSU design to?

> What HS 2.0 tries is to have its own PKI, while also having it be part of
> the Web PKI. I don't think that's a necessarily good or desirable outcome,
> and I think the issue (the otherName) is simply a symptom of the same issue
> we saw with Spain (re: subjectAltNames) and potentially the same issue as
> with the SHA-1 payment terminals. And since we haven't taken meaningful
> steps to address or prevent those, I don't think it's good or desirable to
> mix those two.
> [JR] I think this is a misunderstanding. I’m asking the Web PKI/CAB Forum
> to permit me to create a dual use certificates that effectively function in
> both PKIs. I’m not asking the CAB Forum to support the WFA or WFA PKI other
> than not prohibit their certificates. If there was an actual security
> reason for prohibiting otherNames, I could see the objection. But there’s
> not (other than a vague worry making changes to our document might be more
> difficult in the future)

I agree we are misunderstanding.
I'm stating explicitly I do not believe dual use is good for the Web PKI,
as every other 'dual use' case has shown.
What I don't feel you've really addressed is how do we prevent *this*
dual-use from turning out as badly as the *other* dual-use cases.

That's fundamentally the objection: There's been zero improvement. Your
response above "essentially the WFA participating" doesn't particularly
instill hope (especially as the WFA bits are still kept behind
onerous-enough walls to resources and discussions)

> Further, I think the history with HS 2.0/Passpoint and the OSU interaction
> model highlight a lack of awareness/concern to the Web PKI issues - HS2.0
> just naively assumed that browsers/UAs would blindly trust Cablelabs and
> Digicert, if not explicitly, then implicitly through its members' actions
> (from my limited interactions). That's a critical misunderstanding of the
> Web PKI and root store management.
> [JR] I don’t think they did assume public trust would be blindly
> implemented. Instead, I’m asking for permission to create dual certs. The
> WFA chose Cablelabs and DigiCert for the PKI because we asked them to
> include us, not because they expected browsers to add them to the root
> store. There’s nothing blind about the decision. Plus, I’m only asking for
> permission to create a publicly trusted WFA profile, not embed the WFA
> roots or for Google to support public OSU.

They did assume public trust, and you are asking for Google to support the
WFA/OSU model, but I can understand that this may not be obvious to you. By
creating dual-use certs, all of the HS2.0 risks and concerns become
concerns that you will represent to the Web PKI (as WFA representative, as
you've suggested). Unlike other "multi-use" cases - say, S/MIME - your
certificates will be, from a technical capability point - indistinguishable
from TLS server certificates. This is by design of the OSU model. As such,
any changes to how id-kp-serverAuth certificates work will request, for
those CAs participating in WFA / HS2.0, that their particular usage be

For a technical metaphor, this would be akin to exposing a public interface
from a library. The library maintainers are now on the hook to support that
interface and everyone who depends on it.
For a business metaphor, you're asking the CA/Browser Forum to sign a
support contract to agree to consider HS2.0 use cases and business needs in
the future.

And I'm telling you those have tangible costs associated with that, even if
they're not obvious, we know from historical precedent those costs ended up
being quite large (c.f. SHA-1 exception process), and it's not clear that
there's an actual win here - for security or for users - that justifies
that costs.

> Naturally, and explicitly, my concern is that if/as the HS2.0 OSU profile
> diverges - even though it necessarily requires id-kp-serverAuth in order to
> accomplish the goals as an OSU - then we end up with the SHA-1 problem. So
> the best way to avoid that, as I see it, is to vote No on the (presently)
> necessary condition to allow the OSU and WebPKI profiles to be shared.
> [JR] This is a general worry about any entity using serverAuth. The same
> worry can be extrapolated to vote “no” against particular customers we
> might find troublesome in the future, such as small businesses or cloud
> providers. I may even prove troublesome in the future so we should probably
> prevent me from using WebPKI….

Yes. It is a general worry about any entity using id-kp-serverAuth in cases
not represented in the Forum by the parties responsible for maintaining
those interactions (i.e. the browsers, which control both the root store
*and the software that consumes the root store*).

> Now, it could be that if the Forum voted against this, as I would hope it
> would, HS2.0 would decide to modify the profile to remove the otherName,
> and otherwise just coopt the BRs. They might even go as far as to say the
> OSU PKI is identical to the Web PKI (such as by saying the OSU PKI is the
> intersection of trusted CAs in X). And that would equally be awful, because
> as the Web PKI changes, no consideration is going to be given to the OSU
> PKI's use - the same as we've seen with payment terminals and SHA-1.
> [JR] They’d go the other way. I’m okay with no consideration given to the
> OSU PKI’s use. They’d be okay with that stance as well. Most of them don’t
> care if public trust is involved. I do though.

"Most of them don't care if public trust is involved" is precisely the
awfulness that is HS2.0. You can't not care but expect it to work in the
browser, as it's clear the vendors do.

> I guess I don’t understand the objection other than a vague “Google
> doesn’t plan on using OSU and the WFA may ask for more changes in the
> future”. There’s lots of groups that interact with the WebPKI (such as
> qualified certs, grid certs, the payment industry, etc.) that lead to
> complications when making changes.

And I argue this is bad, and we should try to discourage, not encourage it,
and this reaction is a natural consequence of that. It's a balancing act,
for sure, but in general, the security is greatly improved the *fewer*
consumers we have of the Web PKI (Ideally, just the Web), so that concerns
about interoperability and testing can be addressed at a single layer. As
the Payments example has demonstrated, it doesn't do any good to have 2 out
of the 3 parties consuming the Web PKI, because even if 2 agree, the third
holds everyone back.

> This is why we need a more open participation model. However, the WFA
> isn’t necessarily looking to limit the Web PKI (or change it for that
> matter) but could gain efficiencies with interoperability.

I disagree. It introduces inefficiencies by adding a new layer of concerns
that have to be taken into account, and the efficiencies suggested aren't
actually realized.
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