Just like last year, I managed to be invited to the Privacy Enhancing Technologies Conference to talk about GNOME. First, Simone Fischer-Huebner from Karlstadt University talked about her projects which are on the edge of security, cryptography, and usability, which I find a fascinating area to be in. She presented outcomes of her Prismacloud project which also involves fancy youtube videos…
I got to talk about how I believe GNOME is in a good position make a safe and secure operating system. I presented some case studies and reported on the challenges that I see. For example, Simone mentioned in her talk that certain users don’t trust a software if it is too simple. Security stuff must be hard, right?! So how do measure the success of your security solution? Obviously you can test with users, but certain things are just very hard to get users for. For example, testing GNOME Keysign requires a user not only with a set up MUA but also with a configured GnuPG. This is not easy to come by. The discussions were fruitful and I got sent a few references that might be useful in determining a way forward.
OpenPGP Email Summit
I also attended the OpenPGP Email Summit in Brussels a few weeks ago. It’s been a tiny event graciously hosted by a local company. Others have written reports, too, which are highly interesting to read.
It’s been an intense weekend with lots of chatting, thinking, and discussing. The sessions were organised in a bar-camp style manner. That is, someone proposed what to discuss about and the interested parties then came together. My interest was in visual security indication, as triggered by this story. Unfortunately, I was lured away by another interesting session about keyserver and GDPR compliance which ran in parallel.
For the plenary session, Holger Krekel reported on the current state of Delta.Chat. If you haven’t tried it yet, give it a go. It’s trying to provide an instant messaging interface with an email transport. I’ve used this for a while now and my experience is mixed. I still get to occasional email I cannot decrypt and interop with my other MUA listening on the very same mailbox is hit and miss. Sometimes, the other MUA snatches the email before Delta.chat sees it, I think. Otherwise, I like the idea very much. Oh, and of course, it implements Autocrypt, so your clients automatically encrypt the messages.
Continuing the previous talk, Azul went on to talk about countermitm, an attempt to overcome Autocrypt 1.0‘s weaknesses. This is important work. Because without the vision of how to go from Autocrypt Level 1 to Level 2, you may very well question to usefulness. As of now, Emails are encrypted along their way (well. Assuming MTA-STS) and if you care about not storing plain text messages in your mailbox, you could encrypt them already now. Defending against active attackers is hard so having sort of a plan is great. Anyway, countermitm defines “verified groups” which involves a protocol to be run via Email. I think I’ve mentioned earlier that I still think that it’s a bit a sad that we don’t have the necessary interfaces to run protocols over Email. Outlook, I think, can do simple stuff like voting for of many options or retracting an email. I would want my key exchange to be automated further, i.e. when GNOME Keysign sends the encrypted signature, I would want the recipient to decrypt it and send it back.
Phil Zimmermann, the father of PGP, mentioned a few issues he sees with the spec, although he also said that it’s been a while that he was deeply into this matter. He wanted the spec to be more modern and more aggressively pushing for today’s cryptography rather than for the crypto of the past. And in fact, he wants the crypto of tomorrow. Now. He said that we know that big agencies are storing message today for later analyses. And we currently have no good way of having what people call “perfect forward secrecy” so a future key compromise makes the messages of today readable. He wants post quantum crypto to defeat the prying eyes. I wonder whether anybody has implemented pq-schemes for GnuPG, or any other OpenPGP implementation, yet.
My takeaways are: The keyserver network needs a replacement. Currently, it is used for initial key discovery, key updates, and revocations. I think we can solve some of these problems better if we separate them. For example, revocations are pretty much a fire and forget thing whereas other key updates are not necessarily interesting in twenty years from now. Many approaches for making initial key discovery work have been proposed. WKD, Autocrypt, DANE, Keybase, etc. Eventually one of these approaches wins the race. If not, we can still resort back to a (plain) list of Email addresses and their key ids. That’s as good or bad as the current situation. For updates, the situation is maybe not as bad. But we might still want to investigate how to prevent equivocation.
Another big thing was deprecating cruft in the spec to move a bit faster in terms of cryptography and to allow implementers to get a compliant program running (more) quickly. Smaller topics were the use of PQ safe algorithm and exploitation of backwards incompatible changes to the spec, i.e. v5 keys with full fingerprints. Interestingly enough, a trimmed down spec had already been developed here.