[messaging] TOFU to ease PGP key discovery

[Daniel Roesler]

Most SKS keyservers are personal servers run by volunteers. Many don't
even mirror their sks server to port 80, which is why I got confused
once[1]. There's only a small handful of
companies/institutions/organizations in the pool (*hint* to those on
this list who are a part of organizations who should be in the pool!).

I suspect that asking them to pay for their own root CA chained SSL
cert would be a hard ask, especially when many likely don't buy into
the whole root CA trust idea in the first place (hence why they are
actively supporting Web of Trust infrastructure). Maybe it will be an
easier ask when Let's Encrypt gets up and running :)

-Daniel

[1]: http://moderncrypto.org/mail-archive/messaging/2014/000991.html


On Tue, Feb 10, 2015 at 9:51 AM, Tankred Hase <tankred at whiteout.io> wrote:
> Thanks for pointing that out. I replaced keys.gnupg.net with the fedora server.
>
> Is is just me or do most SKS servers just not believe in TLS? :)
>
> 2015-02-10 17:29 GMT+01:00 Daniel Roesler <diafygi at gmail.com>:
>> Interesting. Thanks for the reply!
>>
>> FYI, keys.gnupg.net just CNAMEs pool.sks.keyservers.net, so you don't
>> need both in your list.
>>
>> $ dig keys.gnupg.net ns +short
>> pool.sks-keyservers.net.
>>
>> I'd also recommend https://keys.fedoraproject.org/, since they enable
>> TLS with a cert chained to a root CA.
>>
>> -Daniel
>>
>> On Tue, Feb 10, 2015 at 2:26 AM, Tankred Hase <tankred at whiteout.io> wrote:
>>> Hi Daniel,
>>>
>>>> 1. Are you using the sks-keyserver server or did you roll your own HKP
>>>> implementation. If you're using sks, can you elaborate on how you
>>>> setup your internal infrastructure and API to the core sks-keyserver?
>>>> If you rolled your own HKP, is there source code available? I'd love
>>>> to find an alternative implementation for HKP that's not written in
>>>> OCaml.
>>>
>>> Our key server is written in node.js, uses MongoDB and runs on AWS
>>> Elastic Beanstalk Infrastructure
>>> (https://aws.amazon.com/elasticbeanstalk/).
>>>
>>> Our server code is pretty specific to our service, so I don't know if
>>> it would make sense to open source that. Right now we are open
>>> sourcing only the client app.
>>>
>>>> 2. You mentioned on HN that you gossip with other keyservers[1]. Since
>>>> the gossip protocol is completely undocumented, do you know much about
>>>> how it works? I've been trying to read the OCaml, but have been
>>>> getting very lost. Hockeypuck[2] claims they can do this, but I don't
>>>> think it's the same gossip protocol, right?
>>>
>>> Our "gossiping protocol" is quite simple at the moment. We didn't
>>> implement a standard. It just act as a proxy to five common SKS
>>> servers. This is mainly because of the lack of CORS and reliability as
>>> mentioned in the blog post.
>>>
>>> If we don't find a verified public key in our directory, we proxy the
>>> following GET request:
>>>
>>> /pks/lookup?op=get&options=mr&search=<emailAddress>
>>>
>>> To these five servers and return the fastest response:
>>>
>>> 'https://pgp.mit.edu',
>>> 'http://pool.sks-keyservers.net',
>>> 'http://keys.gnupg.net',
>>> 'http://keyserver.ubuntu.com',
>>> 'http://pks.gpg.cz'
>>>
>>> These were the most reliable servers in my tests. Especially the
>>> ubuntu key server seems to be the fastest most of the time.
>>>
>>>> 3. When gossiping, do you accept new keys from other sources that have
>>>> a @whiteout.io domain? If I create a public key for "John Smith
>>>> <john.smith at whiteout.io>" and upload it to pgp.mit.edu, will that be
>>>> synced with your database?
>>>
>>> We don't sync. We proxy requests for fetches and uploads.
>>>
>>>> Third, FYI, there is CORS support for sks keyservers as of 1.1.5.
>>>> Also, many keyservers are mirrored on port 443 and using root CA
>>>> signed certs. I created an ajax publickey.js demo[3] using the
>>>> https://keys.fedoraproject.org/ keyserver. You're right, though, that
>>>> you can't just use hkps.pool.sks-keyservers.net, since the TLS
>>>> certificate in that pool must be signed by the SKS CA (which isn't a
>>>> root CA in pretty much every browser).
>>>
>>> Good to know thanks!
>>>
>>> Tankred
>>>
>>>
>>>> Thanks again!
>>>> Daniel
>>>>
>>>> [1]: https://news.ycombinator.com/item?id=9013852
>>>> [2]: https://hockeypuck.github.io/
>>>> [3]: https://diafygi.github.io/publickeyjs/
>>>>
>>>> On Mon, Feb 9, 2015 at 12:58 AM, Tankred Hase <tankred at whiteout.io> wrote:
>>>>> Hi,
>>>>>
>>>>> we've added HKP key server support to Whiteout Wail and have written a
>>>>> post about usability. Though I'd share it here:
>>>>>
>>>>> https://blog.whiteout.io/2015/02/06/making-pgp-key-management-invisible-so-johnny-can-encrypt/
>>>>>
>>>>> Thanks for any feedback!
>>>>>
>>>>> Tankred
>>>>>
>>>>> --
>>>>> Whiteout Networks GmbH c/o Werk1
>>>>> Grafinger Str. 6
>>>>> D-81671 München
>>>>> Geschäftsführer: Oliver Gajek
>>>>> RG München HRB 204479
>>>>> _______________________________________________
>>>>> Messaging mailing list
>>>>> Messaging at moderncrypto.org
>>>>> https://moderncrypto.org/mailman/listinfo/messaging
>>>
>>> --
>>> Whiteout Networks GmbH c/o Werk1
>>> Grafinger Str. 6
>>> D-81671 München
>>> Geschäftsführer: Oliver Gajek
>>> RG München HRB 204479
>
> --
> Whiteout Networks GmbH c/o Werk1
> Grafinger Str. 6
> D-81671 München
> Geschäftsführer: Oliver Gajek
> RG München HRB 204479