Re: Clarification about Ballot 193 and validity of a certificate issued on March 1st

[Matt Palmer via dev-security-policy]

On Fri, Apr 20, 2018 at 01:30:49PM +, Tim Shirley via dev-security-policy 
wrote:
> This is why I'm not a fan of such precise enforcements of date-related
> compliance.  There are a lot of different ways to interpret dates/times,
> but none of the readings materially change the net effect of the rule. 
> That is, all readings change the max validity period to ~825 days (which
> itself is subject to debate as to its precise meaning in terms of seconds)
> within a day or two of each other.  So, enforcing the date as Mar 1 as
> opposed to Mar 2 doesn't seem to add a lot of value and leads to confusion
> like this.

Same thing goes the other way, though -- CAs trying to skate too close to
the line to extract maximum "value" out of the old rules also doesn't add a
lot of value, and leads to confusion like this.  If the CA had decided to
not issue certificates over 825 days after, say, Feb 25, there wouldn't have
been any confusion either.  Exact same reasoning applies to bumping up
against the ambiguity of the 825 day limit -- if a CA wants to avoid any
possibility of confusion, they can just be conservative in what they send,
and not issue certificates over, say, 820 days in length.

Live life on the edge, and you're going to fall off now and then.

- Matt

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Re: Policy 2.6 Proposal: Require separate intermediates for different usages (e.g. server auth, S/MIME)

[Wayne Thayer via dev-security-policy]

On Thu, Apr 19, 2018 at 8:40 PM, Jakob Bohm via dev-security-policy <
dev-security-policy@lists.mozilla.org> wrote:

> On 17/04/2018 20:24, Wayne Thayer wrote:
>
>> This proposal is to require intermediate certificates to be dedicated to
>> specific purposes by EKU. Beginning at some future date, all newly created
>> intermediate certificates containing either the id-kp-serverAuth or
>> id-kp-emailProtection EKUs would be required to contain only a single EKU.
>>
>> Arguments for this requirement are that it reduces risk of an incident in
>> which one type of certificate affecting another type, and it could allow
>> some policies to be restricted to specific types of certificates.
>>
>>
> One case that needs to be considered is specifying a set of closely
> related EKUs, which are desirable to include in the same end entity
> certificate.  A typical combination would be emailProtection and
> clientAuth, for the same identity in the EE cert.
>
> I believe the language I proposed takes care of this:
https://github.com/mozilla/pkipolicy/commit/1ccf31557932ede045f3c2d7bcdac533c5176f18

If there are no additional comments, I will consider this issue to be
resolved and will include this change in version 2.6 of the policy.

- Wayne
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Re: Policy 2.6 Proposal: Add prohibition on CA key generation to policy

[Wayne Thayer via dev-security-policy]

On Tue, Apr 17, 2018 at 6:10 AM, Buschart, Rufus via dev-security-policy <
dev-security-policy@lists.mozilla.org> wrote:

> I believe the wording "insecure electronic channels" leaves a lot of space
> for interpretation. In corporate PKIs for email encryption it is quite
> common to transfer centrally generated email encryption p12-files to mobile
> device management systems, email encryption gateways or directly to mobile
> devices using a wide variety of 'electronic channels'. From the proposed
> wording it doesn't seem to be clear which of those channels are 'insecure'
> and which not. Even if not that common, the same applies for email
> signature p12-files for e.g. email signature on mail gateways or mobile
> devices. Most of the mobile devices out in the field neither support
> hardware token, key-pair-generation in the mailer software nor installation
> of downloaded p12-files (prohibited by app sandboxing).
>
> Maybe it would be possible to restrict the new wording to the EKU
> kp-ServerAuth first and have a detailed discussion about email-encryption
> and user authentication with more interested parties in the next months?
>

Again, this is not new wording. It's already a requirement:
https://wiki.mozilla.org/CA/Forbidden_or_Problematic_Practices#Distributing_Generated_Private_Keys_in_PKCS.2312_Files

Having said that, could we instead be more specific by replacing "insecure
electronic channels" with "unencrypted email"? Limiting the scope of this
statement to id-kp-serverAuth is meaningless since we forbid CA key
generation for server certificates.

- Wayne
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Re: Policy 2.6 Proposal: Require CAs to support problem reports via email

[Wayne Thayer via dev-security-policy]

At this point we have a few choices:

1. Do nothing about requiring email as a problem reporting mechanism.
Instead, take on the related issues of disclosure of the reporting
mechanism and receipt confirmation in Mozilla policy, via the CAB Forum, or
both.
2. Go ahead with the proposal to require email, but allow CAs to require
some special, but standardized identifier be placed in the message that
they can filter on. For example, CAs could ignore messages sent to their
problem reporting address unless the subject contains the phrase "problem
report".
3. Develop some new problem reporting mechanism that solves the problems
with email and forms. For example, we could require CAs to accept problem
reports posted to this list, but build in some additional time in which to
"receive" the report by reading list messages. Or we could require CAs to
accept problem reports via Bugzilla. We already see problems being reported
via these mechanisms and require CAs to monitor both of them, just not on a
24x7 basis.

The first option ('do nothing') is currently in the lead, so I would
especially like to hear from anyone who wants to argue for a different
solution.

- Wayne
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Re: Clarification about Ballot 193 and validity of a certificate issued on March 1st

[sleevi--- via dev-security-policy]

On Friday, April 20, 2018 at 9:31:32 AM UTC-4, Tim Shirley wrote:
> First of all, it's important to distinguish between the BR requirement, which 
> is defined in terms of certificate *issuance* dates, and the value in the 
> "Not Before" field.  I'm guessing the "Not Before" value in this certificate 
> is not the actual issuance timestamp, since it's unlikely it was issued right 
> at the stroke of midnight.  The CA is probably rounding, but we don't know if 
> they're rounding up or down.  But it would only be mis-issuance if the 
> issuance occurred outside of the allowed time window.  There's nothing I can 
> see to show when the certificate was actually issued; it first showed up in 
> CT logs on March 13, so we know it was issued on or before that, but that's 
> all we know for sure about the issuance time.
> 
> So what is the allowed time window according to the BRs?  I'd argue that the 
> intent was that it be >=.  If you read the first bullet's "after" as >, then 
> you have to also read the second bullet's "prior to" as <.  So what rule 
> applies to certificates issued ON March 1, 2018?  Apparently none.  Certainly 
> that wasn't the intent, which is why I interpret the requirement as >=.  That 
> is, the dividing line is the moment in time when we moved from February into 
> March, such that one rule or the other is always in effect.

I agree, it was not the intent, nor is it consistent with the other 
modifications in 193 ( 
https://cabforum.org/2017/03/17/ballot-193-825-day-certificate-lifetimes/ ).

> But even if you accept my premise there, then you have to ask "in what 
> timezone?"  March 1 00:00:00 2018 GMT in North America is February 28.  So I 
> could see someone making the argument that issuance at that moment in time is 
> fine if the CA is in North America but it's mis-issuance if the CA is in 
> Europe, since the requirements don't state that the measurement is UTC.  This 
> is why I'm not a fan of such precise enforcements of date-related compliance. 
>  There are a lot of different ways to interpret dates/times, but none of the 
> readings materially change the net effect of the rule.  That is, all readings 
> change the max validity period to ~825 days (which itself is subject to 
> debate as to its precise meaning in terms of seconds) within a day or two of 
> each other.  So, enforcing the date as Mar 1 as opposed to Mar 2 doesn't seem 
> to add a lot of value and leads to confusion like this.

I'm curious how auditors would view this, since I think this says that's all 
that matters.

>From the client side, we continue to take the most restrictive interpretation 
>that is reasonable, and thus in Chrome, any certificate whose notBefore is >= 
>2018-03-01 00:00:00 UTC and whose difference (in days measured as 60*60*24 
>seconds) is greater than 825 days from the notAfter is rejected.
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Re: Clarification about Ballot 193 and validity of a certificate issued on March 1st

[Rob Stradling via dev-security-policy]

On 20/04/18 14:30, Tim Shirley via dev-security-policy wrote:

First of all, it's important to distinguish between the BR requirement, which is defined in terms 
of certificate *issuance* dates, and the value in the "Not Before" field.  I'm guessing 
the "Not Before" value in this certificate is not the actual issuance timestamp, since 
it's unlikely it was issued right at the stroke of midnight.  The CA is probably rounding, but we 
don't know if they're rounding up or down.  But it would only be mis-issuance if the issuance 
occurred outside of the allowed time window.  There's nothing I can see to show when the 
certificate was actually issued; it first showed up in CT logs on March 13, so we know it was 
issued on or before that, but that's all we know for sure about the issuance time.

So what is the allowed time window according to the BRs?  I'd argue that the intent was that it be >=.  If 
you read the first bullet's "after" as >, then you have to also read the second bullet's 
"prior to" as <.  So what rule applies to certificates issued ON March 1, 2018?  Apparently none.  
Certainly that wasn't the intent, which is why I interpret the requirement as >=.


Indeed, I'm sure that wasn't the intent.  However, if the BRs don't say 
what the BRs intend to say, then the fault is with the BRs rather than 
with the CA that adheres to what the BRs actually say.  What the BRs 
actually say is what matters, because that's what auditors will audit 
against.


"after" is not the same thing as "on or after".  "on or after" is used 
elsewhere in the document to me >=, so TBH I think that reading "after" 
as > is the only correct interpretation.


BTW, over in linting-land, we've already had this same discussion...

https://github.com/awslabs/certlint/pull/58

https://github.com/zmap/zlint/pull/195


 That is, the dividing line is the moment in time when we moved from February 
into March, such that one rule or the other is always in effect.

But even if you accept my premise there, then you have to ask "in what 
timezone?"  March 1 00:00:00 2018 GMT in North America is February 28.  So I could 
see someone making the argument that issuance at that moment in time is fine if the CA is 
in North America but it's mis-issuance if the CA is in Europe, since the requirements 
don't state that the measurement is UTC.  This is why I'm not a fan of such precise 
enforcements of date-related compliance.  There are a lot of different ways to interpret 
dates/times, but none of the readings materially change the net effect of the rule.  That 
is, all readings change the max validity period to ~825 days (which itself is subject to 
debate as to its precise meaning in terms of seconds) within a day or two of each other.  
So, enforcing the date as Mar 1 as opposed to Mar 2 doesn't seem to add a lot of value 
and leads to confusion like this.

On 4/19/18, 10:10 PM, "dev-security-policy on behalf of Simone Carletti via 
dev-security-policy" 
 wrote:

 Hello,
 
 I'm investigating an issue on behalf of a customer. Our customer requested a multi-year certificate that was issued on March 1st by Comodo.
 
 Here's the certificate:

 https://crt.sh?id=354042595
 
 Validity

 Not Before: Mar  1 00:00:00 2018 GMT
 Not After : May 29 23:59:59 2021 GMT
 
 The certificate is currently considered invalid at least by Google Chrome.
 
 It's my understanding that Google Chrome uses a >= comparison, which effectively means certificates issued on March 1st are already subject to Ballot 193.
 
 However, it looks like the interpretation of Comodo of Ballot 193 here is based on a > comparison, since the certificate was issued with a 3y validity.
 
 BR 6.3.2 says:
 
 > Subscriber Certificates issued after 1 March 2018 MUST have a Validity Period no greater than 825 days.

 > Subscriber Certificates issued after 1 July 2016 but prior to 1 March 
2018 MUST have a Validity Period no greater than 39 months.
 
 I'd appreciate some hints about whether a certificate issued on March 1st should be considered subject to Ballot 193 or not.
 
 Best,

 -- Simone
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--
Rob Stradling
Senior Research & Development Scientist
Email: r...@comodoca.com
Bradford, UK
Office: +441274730505
ComodoCA.com

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Re: Clarification about Ballot 193 and validity of a certificate issued on March 1st

[Tim Shirley via dev-security-policy]

First of all, it's important to distinguish between the BR requirement, which 
is defined in terms of certificate *issuance* dates, and the value in the "Not 
Before" field.  I'm guessing the "Not Before" value in this certificate is not 
the actual issuance timestamp, since it's unlikely it was issued right at the 
stroke of midnight.  The CA is probably rounding, but we don't know if they're 
rounding up or down.  But it would only be mis-issuance if the issuance 
occurred outside of the allowed time window.  There's nothing I can see to show 
when the certificate was actually issued; it first showed up in CT logs on 
March 13, so we know it was issued on or before that, but that's all we know 
for sure about the issuance time.

So what is the allowed time window according to the BRs?  I'd argue that the 
intent was that it be >=.  If you read the first bullet's "after" as >, then 
you have to also read the second bullet's "prior to" as <.  So what rule 
applies to certificates issued ON March 1, 2018?  Apparently none.  Certainly 
that wasn't the intent, which is why I interpret the requirement as >=.  That 
is, the dividing line is the moment in time when we moved from February into 
March, such that one rule or the other is always in effect.

But even if you accept my premise there, then you have to ask "in what 
timezone?"  March 1 00:00:00 2018 GMT in North America is February 28.  So I 
could see someone making the argument that issuance at that moment in time is 
fine if the CA is in North America but it's mis-issuance if the CA is in 
Europe, since the requirements don't state that the measurement is UTC.  This 
is why I'm not a fan of such precise enforcements of date-related compliance.  
There are a lot of different ways to interpret dates/times, but none of the 
readings materially change the net effect of the rule.  That is, all readings 
change the max validity period to ~825 days (which itself is subject to debate 
as to its precise meaning in terms of seconds) within a day or two of each 
other.  So, enforcing the date as Mar 1 as opposed to Mar 2 doesn't seem to add 
a lot of value and leads to confusion like this.

On 4/19/18, 10:10 PM, "dev-security-policy on behalf of Simone Carletti via 
dev-security-policy" 
 wrote:

Hello,

I'm investigating an issue on behalf of a customer. Our customer requested 
a multi-year certificate that was issued on March 1st by Comodo.

Here's the certificate:
https://crt.sh?id=354042595

Validity
Not Before: Mar  1 00:00:00 2018 GMT
Not After : May 29 23:59:59 2021 GMT

The certificate is currently considered invalid at least by Google Chrome.

It's my understanding that Google Chrome uses a >= comparison, which 
effectively means certificates issued on March 1st are already subject to 
Ballot 193.

However, it looks like the interpretation of Comodo of Ballot 193 here is 
based on a > comparison, since the certificate was issued with a 3y validity.

BR 6.3.2 says:

> Subscriber Certificates issued after 1 March 2018 MUST have a Validity 
Period no greater than 825 days.
> Subscriber Certificates issued after 1 July 2016 but prior to 1 March 
2018 MUST have a Validity Period no greater than 39 months.

I'd appreciate some hints about whether a certificate issued on March 1st 
should be considered subject to Ballot 193 or not.

Best,
-- Simone
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