[cabfpub] AIA chasing

J.C. Jones jc at mozilla.com
Mon Apr 3 19:32:55 UTC 2017

Quick note: This doesn't operate on anything but end-entities, which Ryan
pointed out is not a complete picture itself, either.

It should be straightforward to modify for that, and PRs are welcome if
anyone wants to make those changes before I get a chance.


On Mon, Apr 3, 2017 at 12:10 PM, J.C. Jones <jc at mozilla.com> wrote:

> I'm afraid that hasn't been considered, as release of any of the data set
> would require legal review.
> Something I could audit and then run locally would be ideal. I've started
> such a tool at https://github.com/jcjones/aia-chaser (and just made it
> mostly work, I think), but it will take a little more time before I can
> process the data with it.
> Review is welcome.
> On Mon, Apr 3, 2017 at 10:12 AM, Ryan Sleevi <sleevi at google.com> wrote:
>> Considering that SSLLabs offers such a tool, has Mozilla considered
>> reaching out to them to exercise a scan of the subset of hosts you're
>> interested in, and sharing that data?
>> On Mon, Apr 3, 2017 at 1:08 PM, J.C. Jones <jc at mozilla.com> wrote:
>>> Ryan,
>>> As mentioned in the bug discussion, it's not to be taken that 5.88% is
>>> gospel, rather that it's 1) a very noisy indication of the effect fetching
>>> would have on total errors, and 2) a call for interested community members
>>> to help us do more with the data.
>>> More sophisticated analysis is absolutely welcome; we have both the
>>> certificate dataset and the hostname dataset which we can operate on. If
>>> someone were interested in writing a tool that, given a host, would
>>> determine whether AIA fetching would avoid a connection error, I'd be happy
>>> to run it and provide the results to the community.
>>> (Note to implementers, we'd need to probably provide Moz's trusted roots
>>> as a configuration item, too)
>>> Cheers,
>>> J.C.
>>> Crypto Engineering
>>> On Mon, Apr 3, 2017 at 9:08 AM, Ryan Sleevi via Public <
>>> public at cabforum.org> wrote:
>>>> That is most unfortunate.
>>>> It doesn't look like the code in https://gist.github.com/moz
>>>> keeler/29754494dcdb3b169483595283f29923 fully accounts for the value
>>>> of AIA with respect to finding alternative paths on such connections. That
>>>> is, it seems like it undercounts for situations such as:
>>>> Leaf -> Intermediate 1 -> Intermediate 2 -> Old CA
>>>>         -> Intermediate 1 -> Intermediate 2' -> New CA
>>>>         -> Intermediate 1' -> New CA
>>>> The analysis Mozilla performed only appeared to examine the end-entity
>>>> certificate, as noted in https://bugzilla.mozilla.or
>>>> g/show_bug.cgi?id=399324#c80 . However, Chrome's experience with AIA
>>>> is that it is most useful for covering the root key rollover and
>>>> intermediate rollover scenarios. I can think of a number of CA members who
>>>> have exercised this code path, but such data was excluded from your
>>>> analysis.
>>>> I appreciate you looking into this matter, though, and for ensuring the
>>>> data and tools were publicly available in order to perform such an analysis.
>>>> An alternative methodology to examine would be to examine the supplied
>>>> chains from the subset of servers (or user error reports) for which you're
>>>> interested in, and determine whether there exists a path to a known Mozilla
>>>> trust anchor. For example, you could use the CCADB disclosures, crt.sh
>>>> dataset (which handedly already groups by ca_id), or directly from
>>>> Certificate Transparency log servers. For such situations where the server
>>>> did not supply a path that immediately resolved, but one or more paths was
>>>> known to Mozilla, you could examine whether or not the AIA identity
>>>> provided by the common elements in that path (even if the only common
>>>> element was the leaf) would have provided one or more intermediates known
>>>> to be valid.
>>>> I do hope you reconsider, because it does appear that the testing
>>>> methodology was flawed.
>>>> On Mon, Apr 3, 2017 at 10:51 AM, Gervase Markham via Public <
>>>> public at cabforum.org> wrote:
>>>>> Participants may be interested in some recent research we did on AIA
>>>>> chasing:
>>>>> https://bugzilla.mozilla.org/show_bug.cgi?id=399324#c80
>>>>> The upshot is that Firefox has no plans to implement this feature.
>>>>> Gerv
>>>>> _______________________________________________
>>>>> Public mailing list
>>>>> Public at cabforum.org
>>>>> https://cabforum.org/mailman/listinfo/public
>>>> _______________________________________________
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