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 May 2017 : Saturday Style Switch #
Kat and Seb's disparaging remarks about the previous style on this site finally got to me (I know you love the eighties vibe really, guys). The new theme on the site is called Bokeh, in homage to the beautiful and clever shader written by Krzysztof Narkowicz, who kindly allowed me to use an amended version for the background.

Although I know some people (naming no names1) will be unhappy with the high-contrast white background, I hope in general you like it. You can always switch to any of the previous styles if you don't like it, of course.

1 Seb.
3 May 2017 : Pico in the Wild: Replacing Passwords, One Site at a Time #
I've posted a short synopsis of the Pico team's time in Paris at EuroS&P and EuroUSEC up on the Computer Lab's Light Blue Touchpaper blog. That's my first post to the blog, although not the first Pico post.
30 Apr 2017 : Pico in the Wild: Replacing Passwords, One Site at a Time #
Another preprint, this time the EuroUSEC 2017 paper Seb, Claudio, Graeme, Kat, Frank and I published in collaboration with Toshiyuki Masui of Keio University. In the paper you'll found the results from our user trial of Pico on the Gyazo website, where real users tried out real Pico and we evaluated their use of and reactions to it. You can find the paper on my publications page. I've just arrived back from Paris where Kat presented the work at the workshop on usable security. There were some great papers, most of which involved user studies of one form or another. We heard lots of interesting insights into how users approach security and respond to different interfaces designed to support security.
11 Apr 2017 : Explicit delegation using configurable cookies #
A preprint of my paper published with Graeme Jenkinson and Frank Stajano, discussing how configurable Web cookies can be used for account delegation, is now up on my publications page. The paper should appear in a Springer LNCS volume in due course.
8 Mar 2017 : Come develop code with us on the Pico project #
At Pico we're looking for an exceptional programmer, ideally with iOS/macOS experience, to help us rid the world of passwords. If you're interested to join an amazing team at the University of Cambridge, check out the details on the job site. Closing date is 18th April.