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"
<dev-security-policy-bounces+tshirley=trustwave....@lists.mozilla.org on behalf
of dev-security-policy@lists.mozilla.org> 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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