I did flag that part as wearing my personal hat 😊.

The Trust Italia Sub CA is an example of where confusion may arise in the 
policy and where the complexity arises in these relationships. This was not 
necessarily a “new” CA from what I understood. This is also why I qualified the 
shut down in 2020 as the non-browser TLS. We aren’t expanding the sub CAs 
beyond what exists while we figure out what to do with existing infrastructures 
that are using them.

That said, still wearing a personal hat, I do think the community should have 
access to this information and review the entities that transitively chain up 
to the Mozilla root program for sMIME or TLS. There should be a review of all 
these sub CAs, including the Trust Italia one we replaced. The only reason I 
can see grandfathering is if there are too many to review at one time. Then 
grandfather the new ones and review before a new CA is required to issue. 
That’ll spur CAs to bring the on-prem Sub CAs forward for review.

The bigger question to me, is how should this review take place? Should the 
root CA sponsor the sub CA and talk about the infrastructure and operations? I 
think there should be an established process of how this occurs, and the 
process is probably slightly different than roots because of the extra party 
(root CA) involved.

From: Wayne Thayer <wtha...@mozilla.com>
Sent: Friday, October 4, 2019 12:40 PM
To: Jeremy Rowley <jeremy.row...@digicert.com>
Cc: mozilla-dev-security-policy <mozilla-dev-security-pol...@lists.mozilla.org>
Subject: Re: Policy 2.7 Proposal:Extend Section 8 to Encompass Subordinate CAs

Thanks Jeremy.

On Thu, Oct 3, 2019 at 5:06 PM Jeremy Rowley 
<jeremy.row...@digicert.com<mailto:jeremy.row...@digicert.com>> wrote:
Hey Wayne,

I think there might be confusion on how the notification is supposed to happen. 
Is notification through CCADB sufficient? We've uploaded all of the Sub CAs to 
CCADB including the technically constrained ICAs. Each one that is 
hosted/operated by itself is marked that way using the Subordinate CA Owner 
field. Section 8 links to emailing 
certifica...@mozilla.org<mailto:certifica...@mozilla.org> but operationally, 
CCADB has become the default means of providing this notice. If you're 
expecting email, that may be worth clarifying in case CAs missed that an email 
is required. I know I missed that, and because CCADB is the common method of 
notification there is a chance that notice was considered sent but not in the 
expected way.

Considering that section 8 links to an email address where it states "MUST 
notify Mozilla<mailto:certifica...@mozilla.org>", I'm skeptical that there is 
confusion, but I do agree that it makes sense for the notification to be 
triggered via an update to CCADB rather than an email. I'll look in to this.

There's also confusion over the "new to Mozilla" language I think. I 
interpreted this language as organizations issued cross-signs after the policy. 
For example, Siemens operated a Sub CA through Quovadis prior to policy date so 
they aren't "new" to the CA space even if they were re-certified.

That's the correct interpretation, barring any further clarifications...

However, they would be new in the sense you identified - they haven't gone 
through an extensive review by the community.  If the goal is to ensure the 
community review happens for each Sub CA, then requiring all recertifications 
to go through an approval process makes sense instead of making an exception 
for new. I'm not sure how many exist currently, but if there are not that many 
organizations, does a grandfathering clause cause unnecessary complexity? I 
realize this is not in DigiCert's best interest, but the community may benefit 
the most by simply requiring a review of all Sub CAs instead of trying to 
grandfather in existing cross-signs.  Do you have an idea on the number that 
might entail? At worst, we waste a bunch of time discovering that all of these 
are perfectly operated and that they could have been grandfathered in the first 
place. At best, we identify some critical issues and resolve them as a 

It appears to be at least 2 dozen organizations, based on the "subordinate CA 
owner" field in CCADB. I say "at least" because, as Dimitris noted, we're just 
now identifying intermediates that are incorrectly labeled as falling under the 
parent certificate's audits.

If there are a significant number of unconstrained on-prem CAs, then language 
that requires a review on re-signing would be helpful.  Perhaps say "As of X 
date, a CA MUST NOT sign a non-technically constrained certificate where 
cA=True for keys that are hosted external to the CA's infrastructure or that 
are not operated in accordance with the issuing CA's policies and procedures 
unless Mozilla has first granted permission for such certificate"? The wording 
needs work of course, but the idea is that they go through the discussion and 
Mozilla signs off. A process for unconstrained Sub CAs that is substantially 
similar to the root inclusion makes sense, but there is documentation on CCADB 
for the existing ones. Still, this documentation should probably made 
available, along with the previous incident reports, to the community for 
review and discussion. Afterall, anything not fully constrained is essentially 
operating the same as a fully embedded root.

Grandfathering in organizations currently in control of an unconstrained 
subordinate CA, but requiring them to go through an approval process before 
obtaining a new subordinate CA certificate seems like a good approach. I do 
however have concerns about requiring a process similar to the root inclusion 
process. We expect the root CA to take responsibility for the organizations 
they certify, so a lighter process that acts as a verification of the decision 
made by the root CA is appropriate here. To put it another way, applying the 
full root inclusion process to externally operated unconstrained subordinate CA 
certificates is not much different than forbidding them. I do agree that policy 
docs and audits should be made available as part of this review.

Speaking on a personal, non-DigiCert note, I think on-prem sub CAs are a bad 
idea, and I fully support more careful scrutiny on which entities are 
controlling keys. Looking at the DigiCert metrics, the on-prem Sub CAs are 
responsible for over half of the incident reports, with issues ranging from 
missed audit dates to incorrect profile information. The long cycle in getting 
information,  being a middle-man information gathering, and trying to convey 
both Mozilla and CAB forum policy makes controlling compliance very difficult, 
and a practice I would not recommend to any CA. Once you've established a 
relationship as a signer CA (or acquired a relationship), extraditing yourself 
is... difficult.  The certificates end up embedded on smart cards, used by 
government institutions and pinned in weird places. And the unfortunate part is 
you don't have the direct relationship with the end-user to offer counsel 
against some of the practices. That extra abstraction layer between the CA and 
root store program ends up adding a lot more complexity than you'd initially 
think. Delegating the CA responsibility ends up being a bad idea and takes 
years to fix. DigiCert is finally down to the final few TLS sub CAs (5) and 
each are operating in OCSP signing mode only. They'll all be revoked in 2020.

Unless I'm missing something, DigiCert is continuing to issue externally 
operated S/MIME sub CAs, e.g. https://crt.sh/?id=1652799594


-----Original Message-----
From: dev-security-policy 
 On Behalf Of Wayne Thayer via dev-security-policy
Sent: Thursday, October 3, 2019 2:45 PM
To: mozilla-dev-security-policy 
Subject: Re: Policy 2.7 Proposal:Extend Section 8 to Encompass Subordinate CAs

I'd like to revisit this topic because I see it as a significant change and am 
surprised that it didn't generate any discussion.

Taking a step back, a change [1] to notification requirements was made last 
year to require CAs that are signing unconstrained subordinate CAs (including 
cross-certs) controlled by a different organization to notify Mozilla. We have 
received few, if any, notifications of this nature, so I have to wonder if CAs 
are adhering to this requirement.

This requirement applies as follows:

an organization other than the CA obtains control of an unconstrained
> intermediate certificate (as defined in section 5.3.2 of this policy)
> that directly or transitively chains to the CA's included
> certificate(s);

Is the "obtains control" language being interpreted to mean that this only 
applies when control of the private keys change, and not when a CA signs a key 
controlled by a different organization? I believe the intent is for this to 
apply in both situations - otherwise it is trivial to bypass.

The new change [2] proposed for version 2.7 of our policy goes one step further 
and places transfers and signings of unconstrained subordinate CAs clearly in 
the scope of section 8.1, including the following language:

If the receiving or acquiring company is new to the Mozilla root program,
> it must demonstrate compliance with the entirety of this policy and
> there MUST be a public discussion regarding their admittance to the
> root program, which Mozilla must resolve with a positive conclusion in
> order for the affected certificate(s) to remain in the root program.
> If the entire CA operation is not included in the scope of the
> transaction, issuance is not permitted until the discussion has been resolved 
> with a positive conclusion.

That means any organization "new to the Mozilla root program" for which a CA 
signs an unconstrained subordinate CA or cross-cert must go through an approval 
process including a public discussion before issuing certificates in order to 
comply with this policy.

It also means that we need to decide what "new to the Mozilla root program"
means. Organizations that control unconstrained subordinate CAs have not been 
considered members of the program in the past, so it's easy to argue that every 
such organization will be "new to the Mozilla root program"
if/when this policy goes into effect. However, it may be more practical to 
"grandfather in" organizations that are currently in control of unconstrained 
subordinate CAs.

This also raises the question of what it means to "demonstrate compliance with 
the entirety of this policy". Section 8.1 has historically applied to companies 
acquiring root CAs and we have not required them to go through the entire 
inclusion process - only a public discussion. Should that same interpretation 
apply to unconstrained subordinate CA?

Before proposing any changes, I'd like to ask for everyone's input on these and 
any other concerns stemming from this policy proposal.

- Wayne


On Fri, May 10, 2019 at 1:58 PM Wayne Thayer 
<wtha...@mozilla.com<mailto:wtha...@mozilla.com>> wrote:

> Having received no comments on these proposed changes, I plan to
> include them in version 2.7 of our policy.
> - Wayne
> On Fri, Apr 19, 2019 at 11:55 AM Wayne Thayer 
> <wtha...@mozilla.com<mailto:wtha...@mozilla.com>> wrote:
>> Ryan Sleevi made the following proposal:
>> Issue #122 [1] previously discussed Section 8 in the context of
>>> subordinate CAs, with a change [2] being made to include subordinate
>>> CAs (in the context of Section 5.3.2) within scope of notification 
>>> requirements.
>>> However, as presently worded, it's ambiguous as to whether or not
>>> Sections 8.1 through 8.3 also apply to subordinate CAs, or whether
>>> the only disclosure required is upon the initial introduction of the 
>>> subordinate.
>>> This confusion results from language such as in Section 8.1, "or
>>> when an organization buys the private key of a certificate in
>>> Mozilla's root program", implying that private keys which
>>> transitively chain to a root certificate within Mozilla's program are 
>>> exempt from such requirements.
>>> This ambiguity creates incentives for situations such as
>>> cross-signing CAs that might otherwise or have been otherwise
>>> rejected from direct inclusion within the Mozilla program. It
>>> further creates issues with respect to the supervision of audits and 
>>> auditors.
>>> While it is true that the signing CA accepts the risk that an
>>> unfavorable verdict on the subordinate may impact the root, the cost
>>> of such a decision is primarily borne by Mozilla and the broader
>>> community, in that they are responsible for the collateral ecosystem
>>> challenges and devising appropriate solutions. This has been
>>> demonstrated, for example, through the discussion of Symantec issues [3].
>>> Because Mozilla and the community bear significant cost, especially
>>> as more time passes and more certificates are issued, the following
>>> changes are suggested:
>>>    1. Align Section 8, and its subsections, with language similar to
>>>    that of Section That is, that the policy is applicable to a CA 
>>> and
>>>    all subordinate CAs technically capable of issuing (server or e-mail)
>>>    certificates
>>>    2. With respect to Section 8.1, extend the requirements of the last
>>>    paragraph to the issuance of subordinate CA certificates. Namely, if the
>>>    private key is in possession of an entity that is new to the Mozilla root
>>>    program, or subject to a CP or CPS that is new to the Mozilla Root 
>>> Program,
>>>    that prior to the issuance of such a certificate, there be a public
>>>    discussion that results in a favorable conclusion.
>>> With the current policy as written, an existing/included root CA
>>> that plans to exit the CA business might be prohibited (by virtue of
>>> Section
>>> 8.1) from selling the business or (by virtue of Section 8.3) from
>>> transferring the private key material. However, they are fully
>>> permitted to cross-certify a new 'root' and then proverbially close
>>> up shop - with no consideration for if their root gets removed as a
>>> consequence. These are the same set of concerns that led to the
>>> introduction of Section 8, but today exist due to the ambiguity with 
>>> respect to the subsections.
>> I've proposed a fix for this issue:
>> https://github.com/mozilla/pkipolicy/commit/175aed5f145ae0f29735a1380
>> 1a5639e70f1f0a8 It also attempts to clarify the applicability of
>> section 8.3 as "only"
>> when section 8.1 and/or section 8.2 also apply.
>> This is https://github.com/mozilla/pkipolicy/issues/169 and
>> https://github.com/mozilla/pkipolicy/issues/140
>> I will greatly appreciate everyone's input on this topic. In
>> particular, I would like to hear from CAs that would be affected by
>> the requirement for any new subordinate CAs to go through a public
>> discussion before issuing certificates, with the outcome being
>> positive or else the subordinate CA certificate will be added to OneCRL 
>> (section 8.1).
>> - Wayne
>> [1] https://github.com/mozilla/pkipolicy/issues/122
>> [2]
>> https://github.com/mozilla/pkipolicy/commit/7a33f1d065733c19b6030261c
>> 1a11f860c30dc10 [3] https://wiki.mozilla.org/CA:Symantec_Issues
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