[cabfpub] OIDs for DV and OV

Tim Hollebeek THollebeek at trustwave.com
Tue Oct 7 07:10:26 MST 2014


For what it’s worth, browsers are not the only end entities that rely upon WebTrust and BRs.  This is out of scope for the CAB forum, but forums and standards bodies should always be aware that other standards bodies may be relying upon their standards for “security goodness”.  If you’re a browser, you don’t care.  If you’re a bank … you care quite a bit.

-Tim

From: public-bounces at cabforum.org [mailto:public-bounces at cabforum.org] On Behalf Of Jeremy.Rowley
Sent: Monday, October 06, 2014 10:22 PM
To: Ryan Sleevi
Cc: Dean Coclin; public at cabforum.org
Subject: Re: [cabfpub] OIDs for DV and OV

1) This isn't a path validation.  Instead, it's an assertion of compliance with a particular section of the BRs.  An assertion of compliance could be required in the intermediate as well, but, for the time-being, the discussion is focused solely on assertions made in end-entity certificates.  Even if the policy OID were required for intermediates, rekeys are not necessarily required since the Forum has a precedent of grandfathering in existing certificates.

2) I believe that point is a red-herring.  Section 11 of the BRs has not materially changed since adoption of the BRs. Because of that, the notBefore date is a "close enough" approximation of compliance.  Besides, Section 11.2 of the BRs has always referred to validation of the legal existence. An assertion of validating the legal existence is sufficient to distinguish between Amazon.com<http://scanmail.trustwave.com/?c=4062&d=is6z1I3cZTSuL0Z97hFkKe6bIbQmWbzqT7MepgArDQ&s=5&u=http%3a%2f%2fAmazon%2ecom> the company and Amazon.com<http://scanmail.trustwave.com/?c=4062&d=is6z1I3cZTSuL0Z97hFkKe6bIbQmWbzqT7MepgArDQ&s=5&u=http%3a%2f%2fAmazon%2ecom> the domain name.

Distinguishing between ETSI and Webtrust audited CAs would be an interesting project, but I think it's out of scope for the current discussion.

3) I think this is speculation.  Since passage of the BRs, most CAs seem to perform similar or nearly identical validation on organizations. Creating more uniform rules about validation of entities was one of the purposes in adopting the BRs. From reviewing CPSs, I think the BRs were successful at this goal.  There may not be a value for the browsers, but I think there are other entities that may disagree.  To Dean's point, I think everyone recognizes that requiring assertion of the BR OID is not something we are proposing for the benefit of the browsers.  Instead, we support it in favor of those monitoring compliance with section 9 and 11 of the BRs and those relying parties who are also interested in evaluating the DV/OV/IV landscape.
Jeremy

On 10/6/2014 8:02 PM, Ryan Sleevi wrote:
Jeremy,

1) The technical means is dependent on how the intermediate _and root_ CAs have been provisioned. As a CA offering EV certificates, no doubt you're aware and familiar with Section 4.2.1.4 and the algorithm described in Section 6.1 of RFC5280, which at best may be summarized as "The policy needs to appear in the intermediate/root"

That is, a policy appearing ONLY in a leaf is by no means an expression of a conforming RFC5280 policy, in that the intermediate CA has not been authorized to issue such certificates by policy. While neither a violation of RFC5280 either (since one may believe that there exist alternative paths that the policy IS valid for), when it comes to programatic validation under the existing hierarchy, a relying party CANNOT apply the RFC5280 path validation to such an "after-the-fact" OID

2) Your comment about Section 11.2 makes me believe you've misunderstood the point I've made in several fora regarding the technical value of such a policy expression. Expressing BR compliance is an act without meaning, since there are multiple versions of the BRs (with different technical and procedural requirements), and which are audited under different regimes (ETSI, WebTrust) which themselves are also versioned and cover different technical aspects.

These permutations are what meaningfully express the issuance policies and practices of a CA - that is, how many are conforming with BR 1.1.9 using WebTrust vs those conforming to BR 1.1.7 using ETSI, etc.

3) The distinction between DV (which is to say, the bare minimum of BR requirements) and OV (which exists as a marketing hodge-podge of optional requirements included in the BRs, but no one set mandating what OV is) is, at it's core, a distinction that varies between CA to CA, and for which no browser expressed support for during our most recent F2F. Just compare Section 9.3.1 with the language in Section 9.2 to see that there's a mismatch between the requirements of the fields.


Again, believing there to be NO value in the expression of a BR OID, and believing that mandating the presence of the OID, when combined with the language in Section 9.3.1, would have the net-effect of introducing more restrictions on the ability of CAs to provide BR-compliant certs, this is not something we're really keen on.

Cheers,
Ryan

On Mon, Oct 6, 2014 at 6:04 PM, Jeremy Rowley <jeremy.rowley at digicert.com<mailto:jeremy.rowley at digicert.com>> wrote:
Technical means exist to express the policy since the OIDs are included in the certificate policy.  Plus, the policy is fairly stable as section 11.2 has not had substantial changes since adoption of the baseline requirements.

How would it require a rekeying of every CA’s hierarchy if the policy were only in the end entity certificate?  At that point, it’s only a profile change.

From: public-bounces at cabforum.org<mailto:public-bounces at cabforum.org> [mailto:public-bounces at cabforum.org<mailto:public-bounces at cabforum.org>] On Behalf Of Ryan Sleevi
Sent: Monday, October 6, 2014 6:51 PM

To: Dean Coclin
Cc: public at cabforum.org<mailto:public at cabforum.org>
Subject: Re: [cabfpub] OIDs for DV and OV

Dean,

You have yet to demonstrate how this would not require a complete rekeying of every CA's hierarchy, given the nature of policy OIDs, to ultimately express a conformance to a policy that is not stable in time, nor consistently audited.

Putting aside whether or not you see value in such an expression of policy, it's more important to just establish whether or not the means to technically express such a policy exist and are reasonable. Then and only then is it useful to discuss whether we should.

On Mon, Oct 6, 2014 at 12:17 PM, Dean Coclin <Dean_Coclin at symantec.com<mailto:Dean_Coclin at symantec.com>> wrote:
So I get the part that Chrome (and likely other browsers in the CA/B forum) don’t intend to distinguish DV and OV certs in any way. Got that. Not a point of contention. In fact, I knew that when I started this thread.  So no need to go down that path anymore. Having different OIDs does not oblige a browser do anything.

I would have expected more negative commentary from CAs but so far there has been none. And only 1 browser has chimed in.

However, browsers are not the only application that use SSL certificates. There are others out there and I distinctly recall a conversation about 2-3 years ago where Paypal (a CA/B member) explicitly asked that these OIDs be mandatory. Brad stated that their security group had deemed DV certs to be a security threat to their ecosystem and wanted an easy programmatic way to distinguish them. At the time, there was some pushback (I don’t believe from browsers) and the OIDs ended up being optional.

It looks as if some CAs do use OIDs in their DV and OV certs but some don’t use the CA/B Forum OIDs (rather their own). This makes it difficult to apply a uniform decision process.

Certs conforming to policy and issued correctly are one aspect that some folks are looking for. The type of certificate is another. One that has not been vetted is different from one that has some vetting completed (other security issues being equal). Perhaps that benefit is not tangible to some but it certainly is to others. I can spew some stats on DV cert use and fraud but that will just muddle this thread so I’ll save it for another day.

Why do browsers care one way or the other if other parties want to make this distinction? The CA/B Forum has defined different baseline standards for these types of certs. Why not make transparency around those standards easy for those that want to draw a distinction?

Certainly would love to hear from some other interested parties.

Thanks,

Dean

From: Ryan Sleevi [mailto:sleevi at google.com<mailto:sleevi at google.com>]
Sent: Thursday, October 02, 2014 8:56 PM

To: Dean Coclin
Cc: public at cabforum.org<mailto:public at cabforum.org>
Subject: Re: [cabfpub] OIDs for DV and OV



On Thu, Oct 2, 2014 at 5:31 PM, Dean Coclin <Dean_Coclin at symantec.com<mailto:Dean_Coclin at symantec.com>> wrote:
Thanks for the response and pointers. I’ve read through the threads but still have additional questions/comments. I’ll readily admit that I don’t understand all the commentary in the Mozilla threads so I apologize if these questions sound somewhat naïve. Happy to be educated:

You've heard repeatedly from several browsers about an explicit non-goal of distinguishing DV and OV. As the Forum is comprised of CAs and Browsers, do we have any Browsers that wish to make such a distinction? If not, it would be wholly inappropriate for the Forum to require it.
>>I haven’t heard of any browsers that want to make that distinction (yet). It is my understanding that the Forum BRs do require an OID for EV certs. So why is it “inappropriate” for the Forum to require OIDs for DV/OV?

Browsers have agreed to make a distinction between EV and !EV, so have required there be a way to detect that.
Browsers have not agreed that there is a distinction between DV or OV, nor is there a need to detect the difference.

That the browsers have required (effectively all stores at this point, AFAIK) is that the root program members be BR compliant. So any new certs issued (technically, independent of the notBefore, and we know CAs regularly backdate from time of issuance, but it's a rough heuristic) are, by definition, BR compliant.


If there are non-browser relying parties interested in such distinctions, the CA can always provide such distinctions themselves.
>>Can you elaborate on what you mean by this? If there’s another way to accomplish the end result, happy to explore further. But it would have to be uniform among all CAs that issue these certs.

I don't see why it needs to be uniform.

The requirement as to what shape it takes is dictated by the relying party applications.
The browsers, as relying party applications, do not and have not yet cared about the shape of DV and OV, and as per our recent F2F, aren't really keen to either.

So having the browsers dictate the shape of the solution seems unnecessary, and an issue for these relying party applications (e.g. Netcraft) to work with CAs.


As someone very keen on programatic checks and detection for misissuance, there's no question that this would NOT meaningfully help address the concerns we see.
>>I wasn’t suggesting that this addition would in any way help you with your programmatic checks for mis-issuance.  Rather, it would make the task for organizations like Netcraft, EFF or others that tabulate statistics on various types of certificates easier to do. Is that not the case?

Not really. These organizations are interested in the same discussions and distinctions we are - what are the certificates being issued and do they conform to the policies that they're supposed to.

We've established that there's no 'uniform' definition of what constitutes OV, only that the BR requires certain vetting steps for certain subject fields that are OPTIONAL. CAs have taken these and marketed them as OV, but there's no such distinction as a level, nor a particular profile spelled out in the appendices as to what constitutes a "DV" vs "OV".

If that was the only degree of distinction required, it's just as easy as checking the Subject fields for any of the OPTIONAL fields.


That is, there would need to be an OID _per revision_ of the BRs, to indicate "which" version of the BRs something was complying to.
>>Fully admit that I don’t understand how this works. But wouldn’t that also be the case for EV (which currently requires this OID)?

YES! And it's one of the many reasons why EV is somewhat muddled for programatic checks or distinctions. And yet this is also necessary because any change in policy, by definition, necessitates a change in OID to (meaningfully) reflect that. And that constitutes rolling a new hierarchy (and updating browsers' lists of recognized EV OIDs)


I’m just trying to suggest a  way that someone can say: X is a DV cert, Y is an OV cert, Z is an EV cert without a doubt. If OIDs are not the place to do that, is there another mechanism available?
I’m sure you are familiar with Ryan Hurst’s blog on how difficult the task currently is.

I am (you're talking about http://unmitigatedrisk.com/?p=203<http://scanmail.trustwave.com/?c=4062&d=is6z1I3cZTSuL0Z97hFkKe6bIbQmWbzqT75KrQMtWw&s=5&u=http%3a%2f%2funmitigatedrisk%2ecom%2f%3fp%3d203> in particular). But I'm also not supportive of encouraging a distinction that we neither recognize nor have plans to recognize, and especially not supportive of mandating such distinctions.

This is especially true, as these distinctions don't offer any tangible security benefits to the Web, as previously discussed.

If we go to the point of mandating anything additional in certificates, which requires a variety of changes in processes, profiles, and CPSes, I want it to have meaningful security value. This change - which, as has been shown by the development of audit standards and then the eventual incorporation of those audit standards into the root programs, and then FINALLY the enforcement of those audit standards of the root programs - would take several years, at BEST, to deploy, and would communicate nothing of actionable value. It's a hard sell.



Thanks,
Dean

From: public-bounces at cabforum.org<mailto:public-bounces at cabforum.org> [mailto:public-bounces at cabforum.org<mailto:public-bounces at cabforum.org>] On Behalf Of Ryan Sleevi
Sent: Thursday, October 02, 2014 3:37 PM
To: Dean Coclin
Cc: public at cabforum.org<mailto:public at cabforum.org>
Subject: Re: [cabfpub] OIDs for DV and OV



On Thu, Oct 2, 2014 at 10:33 AM, Dean Coclin <Dean_Coclin at symantec.com<mailto:Dean_Coclin at symantec.com>> wrote:
Further to today’s discussion on our call, I’d like to get more feedback on a proposal to make a unique standardized OID mandatory for DV and OV certificates in the Baseline Requirements. Currently we have a mandatory OID for EV certificates but optional for OV and DV.  This makes things difficult for at least two groups of constituents:


1.       Relying parties that would like to distinguish between these certificates
You've heard repeatedly from several browsers about an explicit non-goal of distinguishing DV and OV. As the Forum is comprised of CAs and Browsers, do we have have any Browsers that wish to make such a distinction?

If not, it would be wholly inappropriate for the Forum to require it. If there are non-browser relying parties interested in such distinctions, the CA can always provide such distinctions themselves.


2.       Analysts that report on SSL certificate data who have had to issue revised reports because of cert misclassification
As mentioned on the call, this has been discussed with Mozilla in the past - https://groups.google.com/d/msg/mozilla.dev.security.policy/-mCAK5zfhFQ/hEOQK-ubGRcJ<http://scanmail.trustwave.com/?c=4062&d=is6z1I3cZTSuL0Z97hFkKe6bIbQmWbzqT-0Yp1B7DQ&s=5&u=https%3a%2f%2fgroups%2egoogle%2ecom%2fd%2fmsg%2fmozilla%2edev%2esecurity%2epolicy%2f-mCAK5zfhFQ%2fhEOQK-ubGRcJ>

As someone very keen on programatic checks and detection for misissuance, there's no question that this would NOT meaningfully help address the concerns we see.

That is, there would need to be an OID _per revision_ of the BRs, to indicate "which" version of the BRs something was complying to.

I would hope that https://groups.google.com/d/msg/mozilla.dev.security.policy/-mCAK5zfhFQ/2tRUS444krwJ<http://scanmail.trustwave.com/?c=4062&d=is6z1I3cZTSuL0Z97hFkKe6bIbQmWbzqT7IToVF8CQ&s=5&u=https%3a%2f%2fgroups%2egoogle%2ecom%2fd%2fmsg%2fmozilla%2edev%2esecurity%2epolicy%2f-mCAK5zfhFQ%2f2tRUS444krwJ> would capture some of these concerns more fully.

Finally, to do anything meaningful with this in all major clients, it would require that CAs redo their certificate hierarchy, as policy OIDs are inherited. That's a silly thing, especially when CAs are still struggling to migrate from SHA-1 to SHA-256 in their intermediates.


My proposal is for CAs to put in OID X if it’s a DV certificate and OID Y if it’s an OV certificate.

As Rick reminded me on the call, we currently have something like this for EV certificates (except that CAs are free to use the standard OID or define one of their own).

I’d like to hear pros/cons of this. Ryan S indicated that Google would not support such a proposal but we didn’t have time to discuss the reasons.

I’m sure there are both technical and policy reasons. Personally I’d like to focus on the latter but remarks on both are welcome. This proposal doesn’t require anyone to do anything with this data (i.e relying parties can choose whether or not to utilize it).

Thanks,
Dean






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