I'm David Llewellyn-Jones and this is my homepage. I'm a researcher in computer security who's also interested in programming and graphics. You might be interested in my research, my software or my random musings.

Want to know more about me? Here's a personality sketch written by a psychologist when I was in school.

“David is of high intelligence, although lacking in true creativity. He has a need for order and clarity, and for neat and tidy systems in which every detail finds its appropriate place. His writing is rather dull and mechanical, occasionally enlivened by somewhat corny puns and by flashes of imagination of the sci-fi type. He has a strong drive for competence. He seems to have little feel and little sympathy for other people and does not enjoy interacting with others. Self-centered, he nonetheless has a deep moral sense.”

Wow. Harsh. But disturbingly accurate.

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20 Nov 2016 : Certificate ROL 1 #
The TLS cert on my home server was approaching expiration, and in previous years I've been caught out (on one occasion I was left generating certificates on Christmas day!), so I decided to do it early this year. It's got a lot more complex with certificate pinning. I can't just generate a new certificate and use it, but must now maintain multiple simultaneously shifting them all one to the left each year. It needs much more careful planning, given I'm more than capable of forgetting everything from one year to the next. Still, I'm happy to say it's now all done for another few years, and with an A+ rating from SSL Labs no less.
16 Oct 2016 : Fixing snap apps with relocatable DATADIRS #
Playing around with the new snap packaging format, I came up against this DATADIR issue. Of all the many ways to get around it, here's the approach I took for functy.
27 Sep 2016 : Functy code moved to GitLab #
Finally, after many months (actually, more like years!) I've finally got around to moving the Functy code off SourceForge and on to GitLab. Getting it right took a big chunk of my holiday, but I reckon it'll have been worth it.
At the same time I've also split it into two separate projects: functy and libsymbolic. Grab nightly-built deb packages for Ubuntu from my private PPA. For the Windows installer I'm still figuring out where they should go (probably somewhere on this site, once I've moved the content off the now sleeping Functy blog).
SourceForge has been a great resource for such a long time and I'm sad to be moving on, but it's been through a lot recently, and not always in a good way. By contrast GitLab seems to be going in a really good direction. Using it on the Pico project has highlighted its strengths and I'm very optimistic for its future.
22 Sep 2016 : ownNotes 1.8.6 for Sailfish OS #
A new version of ownNotes is now available. The main difference is a fix to allow it to work with more ownCloud installations (specifically, it now also works on installations where the domain root requires different credentials than the ownCloud subfolder). As before the source is on GitHub and the RPM on OpenRepos.
18 Sep 2016 : New ownNotes release 1.8.4 #
Now the new version of ownNotes is available on OpenRepos, and the source is up on GitHub, there's also a page around here somewhere to pull everything together. Thanks go to Benoît Hervier (Khertan) for kindly allowing me to make the new release now he's no longer supporting the Sailfish version.