[cabfpub] Ballot 188 - Clarify use of term "CA" in Baseline Requirements

Ryan Sleevi sleevi at google.com
Tue Feb 28 22:47:09 UTC 2017

Hi Dimitris,

Unfortunately, it doesn't sound like we're on the same page. While I
appreciate the effort you and Ben and others have worked on this, I think
this proposal creates new security vulnerabilities in both ambiguity and

My request would be that you consider withdrawing the ballot or that
members who support this change to No, so that it can be worked on in the
policy group to resolve these issues. I would suggest that given the issues
are, in part I suspect, due to misunderstandings about the
concerns/threats, it might be best to table this until after the F2F.

For example, your response regarding audits is demonstrably incorrect - and
though I believe it emerges from a misunderstanding of effect, even though
we share the common goal - and that alone is reason for serious concern.

On Tue, Feb 28, 2017 at 2:09 AM, Dimitris Zacharopoulos <jimmy at it.auth.gr>

> On 27/2/2017 9:21 μμ, Ryan Sleevi wrote:
> On Mon, Feb 27, 2017 at 10:52 AM, Dimitris Zacharopoulos <jimmy at it.auth.gr
> > wrote:
>> I think this is a potentially problematic definition, in that it relates
>> to the scope of the operations of the audit, as well as matters below that
>> I highlight. I'm hoping the proposers and drafters can clarify (or link to
>> previous discussions) as to the reason in which "or its Affiliate" was
>> introduced into these definitions, or to highlight where it was already a
>> natural and existing part of these definitions.
>> Peter already provided some clarity for this. The "Affiliate" language
>> was not introduced by this ballot. It was already mentioned in several
>> sections of the BRs ( "CA Key Pair Generation", 6.1.2 "Private Key
>> Delivery to Subscriber", 6.2.6 "Private Key Transfer into or from a
>> Cryptographic Module", "Subordinate CA Certificate" and
>> "Subordinate CA Certificates").
> Unfortunately, I think the concern still remains that this is a subtle
> introduction that goes from being scoped to specific sections (as you've
> noted) to now being a foundational concept, which unfortunately 'weakens'
> the BRs, I believe.
> I totally understand and appreciate the intent to align here, especially
> for the cases Peter noted, but I want to especially make sure to highlight
> the issue that "or the Affiliate" can be problematic from a set of scope of
> audits.
> Basically, what's being asked for on this ballot is a trade-off from being
> logically bugged (and I agree, this is an issue we should fix) to something
> that is procedurally weaker, and I'm trying to figure out what the plan is
> to align. From both you and Peter's response, it sounds like you don't
> believe further changes are needed, and this is concerning.
> As far as this ballot is concerned, which is only to clarify the use of
> the term "CA", it does not "weaken" the BRs in any way. The use of the term
> "Affiliate" and policy around it, is already there. I personally (and maybe
> others) feel that the "Affiliate" issue needs to be further discussed and
> even be removed as a way of providing better conditions but this is
> something outside the scope of this ballot.
>> Peter's answer should cover this. Your follow-up questions challenge the
>> fact that the current BRs treat Root Operator's "Affiliates" in a different
>> way than the non-Affiliates but this is a policy matter and should be
>> discussed separately. In any case, I don't think it changes the fact that
>> all Subordinate CAs (whether internally or externally operated) need to be
>> audited. In the case of Internally Operated Subordinate CAs, the audit
>> might be covered in the Root Operator audit, and this information should be
>> included in the audit scope.
> That's the intent - but my question is, where is it specified? I may have
> missed that, and that was the point of raising these concerns: if I'm
> misreading, and it's already addressed, fantastic. But I don't believe it
> is, hence the concern :)
> 8.1: "Certificates that are capable of being used to issue new
> certificates MUST either be Technically Constrained in line with section
> 7.1.5 and audited in line with section 8.7 only, or Unconstrained and fully
> audited in line with all remaining requirements from this section". IMO,
> from this reading, it is clear that all Subordinate CAs MUST be fully
> audited or self-audited (per 8.7) if they use Technically Constrained
> Subordinate CA Certificates. There is no distinction about whether the
> Subordinate CA is "Internal" or "External".
> "Affiliates" in the current BRs have different policy in the following:
>    - The key generation ceremony SHOULD (instead of MUST) be witnessed by
>    an external auditor (
>    - The Policy Identifier MAY (instead of MUST) be present in the
>    Subordinate CA Certificate and the "anyPolicy" identifier MAY (instead of
>    MUST NOT) be used. (
> I believe that's all there is to it.
>> After several discussions within the WG, it was agreed that the most
>> accurate technical language is that "Private Keys sign Certificates".
>> Certificates, don't sign Certificates.
> I understand the "why". I'm more specifically asking three questions:
> 1) Is my interpretation correct?
> 2) Is this desired?
> 3) Is there a plan to fix it?
> From the rest of this section, I can interpret your response as "1) Yes 2)
> No, not necessarily 3) Not really, but we could come up with one". I'm not
> sure if that really provides the level of assurance when considering
> whether to vote on this ballot, even though I agree and understand the why,
> and am relieved it isn't intended.
> Your interpretation for 1) is correct regarding the specific OCSP
> responder question.
> For 2), the WG's desire was to use technically correct language in the
> entire BRs to describe the "signing" process. You had a very specific
> concern about the OCSP responder where RFC 6960 allows either the name of
> the responder of a hash of the responder's public key as the ResponderID so
> even that is taken care of. However, if this concern remains, we will move
> to fixing it.
> For 3), if this concern remains, we will fix it. I would like to ask if
> more members have the same concern, to please speak up.
>> So, according to your example, if the ResponderID was the hash of the
>> Subordinate CA Certificate's public key, it would not be prohibited even
>> though that key would be included in two or more Subordinate CA
>> Certificates. Perhaps the multiple CA Certificates with the same key-pair
>> scenario is not entirely addressed. We could update the BRs to specifically
>> include language for the ResponderID information, if you think people would
>> be puzzled about what information should be included in that field.
> Whether we address this by specifying language fro the ResponderID (which
> seems overly specific) or by addressing the general concern, I'd like to
> see a concrete proposal to address this, ideally before voting concludes.
> So far, the WG thought that the phrase "signed by the Private Key
> associated with a Root CA Certificate or a Subordinate CA Certificate" was
> technically correct and enough to clearly demonstrate a link between a
> Private Key and a Specific CA Certificate. If the corresponding public key
> to that private key is included in another Subordinate CA Certificate, it
> only adds policy requirements around that private key.
> Put differently, if a Private Key is associated with Certificate "SubCA1"
> which is operated by "SubCA1 org" and for some reason the same private key
> is associated with Certificate "SubCA2" which is operated by "SubCA2 org",
> we need to determine what obligations exist for the handling of that
> Private Key for its entire lifecycle and usage, which is the superset of
> SubCA1 and SubCA2. If the requirements surrounding SubCA1 and SubCA1 org
> are "requirements A" and the requirements surrounding SubCA2 and SubCA2 org
> are "requirements B", then the Private Key must meet requirements A+B.
>> In Section 4.9.10 (On-line revocation checking requirements)
>> Was this intentional?
>> This specific change was addressed during the discussion phase (
>> https://www.mail-archive.com/public@cabforum.org/msg02652.html).
> Did you link to the right thread? I cannot find a clear answer, but
> perhaps I'm just missing it. As it stands, I think this alone is
> potentially grounds that we may need to vote against it, because it's a
> clear reduction in assurance.
> The link is from a thread started by Ben. Unfortunately, I couldn't find
> it in the mail-archive so it is pasted here:
> --- BEGIN QUOTE---
> -------- Forwarded Message --------
> Subject:     [cabfpub] Policy Review Working Group's Pre-Ballot to Clarify
> Use of "CA"
> Date:     Thu, 19 Jan 2017 16:44:46 +0000
> From:     Ben Wilson via Public <public at cabforum.org>
> <public at cabforum.org>
> Reply-To:     CA/Browser Forum Public Discussion List
> <public at cabforum.org> <public at cabforum.org>
> To:     CABFPub <public at cabforum.org> <public at cabforum.org>
> CC:     Ben Wilson <ben.wilson at digicert.com> <ben.wilson at digicert.com>
> All,
> The Policy Review Working Group has completed its review of the Baseline
> Requirements for purposes of clarifying use of the term "CA" and related
> terminology.  Please review and comment on the following pre-ballot.  A
> redlined version of the Baseline Requirements is attached to facilitate
> your review and comment.
> I did want to highlight one of the proposed changes that is not related to
> "CA" terminology.   That proposed change is in Section 4.9.10.  The current
> language is ambiguous, and it doesn't say what was originally intended when
> it was adopted.  The current language says, "Effective 1 August 2013, OCSP
> responders for CAs which are not Technically Constrained in line with
> Section 7.1.5 MUST NOT respond with a "good" status for such
> certificates."
> The proposed change would rephrase this sentence to say what was
> originally intended.  It would say, "OCSP responders for Subordinate CA
> Certificates that are Technically Constrained in accordance with Section
> 7.1.5 are exempt from this prohibition on responding with a "good" to OCSP
> requests for the status for such certificates."
> I don't know if anyone is relying on this provision, but its original
> intent was to address concerns by users of legacy CA software / OCSP
> responder software who complained that they could not meet this requirement
> because their OCSP responders were built to rely only on CRLs.
> If this proposed change presents a problem for anybody, it will be removed
> from this ballot and put into its own separate ballot.
> Thanks,
> Ben
> --- END QUOTE---
> Gerv replied on January 25th that he agrees with the proposed change on
> 7.1.5 which basically clears the language. It doesn't reduce the assurance.
> The assurance is already "reduced" in the current BRs. Here is the current
> language in 4.9.10:
> "Effective 1 August 2013, OCSP responders for CAs which are not
> Technically Constrained in line with Section 7.1.5 MUST NOT respond with a
> "good" status for such certificates".
> The new proposed language says exactly the same thing but in a more clear
> way. So, again, the ballot does not propose policy changes (although as we
> said a couple of times, the WG was very tempted to propose policy changes
> to make things better).
>> A typo indeed. It is clear in the red-lined version.
> For future reference, we should try to figure out what version is being
> voted on, when the e-mailed ballot and Red Line disagree :) This is a minor
> issue, but I can easily see more significant issues creeping in, least of
> all, because I have not looked at all at the Red Lined version, because
> that's not the balloted text :)
> Agreed. I guess once we become more familiar with a github process, we
> will use one version over another as authoritative for ballots (most
> probably the github version).
>> In Section 8.7 (Self-Audits)
>>> Replace the last paragraph with:
>>> During the period in which a Technically Constrained Externally Operated
>>> Subordinate CA issues Certificates, the Issuing CA SHALL monitor adherence
>>> to the Issuing CA's Certificate Policy and/or Certification Practice
>>> Statement and the Externally Operated Subordinate CA's Certificate Policy
>>> and/or Certification Practice Statement. On at least a quarterly basis,
>>> against a randomly selected sample of the greater of one certificate or at
>>> least three percent of the Certificates issued by the Externally Operated
>>> Subordinate CA, during the period commencing immediately after the previous
>>> audit sample was taken, the CA SHALL ensure adherence to all applicable
>>> Certificate Policies and/or Certification Practice Statements.
>> Much like several other changes mentioned above, this limits the scope of
>> the existing text from "internal or external" to simply "external". Thus it
>> reduces the scope of examination for internally operated subordinate CA
>> certificates, which may be operated by an Afilliate under a distinct
>> CP/CPS. Is that fair to say?
>> The rest of the section remains the same. It doesn't remove the
>> obligation for the CA (this covers ALL CA organizations, including
>> affiliates) to perform quarterly self-audits.
>> The reasoning for changing the last paragraph to only "Externally
>> Operated Subordinate CAs", was that the language dictates that the "Issuing
>> CA SHALL monitor adherence...". We thought that it doesn't make sense to
>> have one organization monitor adherence to it's own organization. It is
>> already required for the Root CA Operator to adhere to its own CP and/or
>> CPS (that must cover all Internally Operated Subordinate CAs), check
>> against a randomly selected sample, etc, as specified in the first
>> paragraph of section 8.7.
> So I think the point you're making is important, and I'm not cleared where
> it's technically spelled out or required, and do hope you can highlight
> this.
> You're asserting that all Internally Operated Subordinate CAs are operated
> by the Root Operator AND, if I'm understanding correctly, audited to the
> same CP/CPS as the Root CA Certificate - is this correct?
> No. I am saying that it could be, under some circumstances. For example,
> if a Root Operator has an internal department (under the same Management)
> that handle issuances under a specific Subordinate CA Certificate, then
> this Internally Operated Subordinate CA could be covered in the audit of
> the Root Operator. If we're talking about two separate legal entities under
> different Management, then a separate audit report is needed according to
> Section 8.1.
> I haven't found text to normatively require either statement, and that's
> the concern: even if it's the same organization as the Root Operator, the
> possibility for distinct CP/CPSes to exist between the Root CA
> Certificate's policies and the Internally Operated Subordinate CA's
> policies (and/or independent audits) exists, and as much as possible, I
> want to ensure the same consistent duty of care with respect to policies
> and practices. I fear this introduces a loophole for Affiliates to 'skip'
> audits and key protection, even if unintended, so I'm curious if we can
> find a resolution for this within the voting period.
> The requirement for all Subordinate CAs to be audited comes from the first
> paragraph of Section 8.1, as stated above. It leaves no room for
> interpretations and includes ALL Subordinate CAs, Internal or External.
>> Here are the two definitions introduced:
>> *Root CA Operator:*  The top-level Certification Authority (i.e. an
>> organization) whose CA Certificate (or associated Public Key) is
>> distributed by Application Software Suppliers as a trust anchor
>> *Internally Operated Subordinate CA:*  A Subordinate CA Operator,
>> operated by a Root CA Operator or its Affiliate that is in possession or
>> control of the Private Key associated with the Subordinate CA Certificate
>> The Root CA Operator is already -by definition- responsible for all
>> actions related to its Internally Operated Subordinate CAs and Affiliates.
> I disagree, and that's the point of concern. If the Root CA Operator
> included the definition of Affiliates - ergo bringing consistency to the
> scope of audits and operation - then perhaps this issue would be resolved
> (of course, it may introduce new bugs). But as it stands, an Internally
> Operated Sub CA having the "or its Affiliate" creates a loophole in which
> all the policies which apply to a Root CA Operator _don't_ apply to the
> Affiliate, because IOSCAs clearly distinguish Affiliate as "something other
> than the Root CA Operator"
> Does this make sense?
> I believe it is the opposite. To the best of my knowledge and
> understanding (and I hope members can correct me if I'm wrong), IOSCAs are
> treated as "something as the Root CA Operator". That's already captured in
> the BRs today.
>> Voting ends on Thursday March 2 at 22:00 UTC but the remaining issues
>> will be tracked and addressed in a future ballot.
> My hope is something a bit more concrete than future ballot before then,
> because I think some of these concerns are enough to prevent our support
> The voting ends tomorrow and I hope to have addressed some or all your
> concerns. Ben and Tim (and even Peter who attended several of the WG
> meetings) are welcome to add any comments to help addressing these concerns
> even further. I also encourage other members with the same or similar
> concerns who feel they are not properly addressed, to speak up so we can
> decide if we must proceed with amendments. Unfortunately, at the stage we
> are at, the ballot cannot be withdrawn so it can either pass or fail.
> Overall, the ballot has significant language improvements -as many have
> already stated- and it would be nice to have every member's support. Policy
> problems that pre-existed the ballot, still remain but that was left
> untouched on purpose, so we could proceed with policy improvements after we
> had a consistent language and definitions throughout the BRs.
> Best regards,
> Dimitris.
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