Leo (he/his) || Janis (she/her) || * (they/them)

I'm a genderqueer hacker from Berlin. Currently working in IT Security, my interests are also in systems engineering, typesetting/typography and cryptography. Additionally, I love teaching about these subjects as well as engaging in politics, having been part of the student's "Fachschaftsinitiative" of the CS department at the Freie Universität Berlin and active in various roles in the Ausbildungskommission, Institutsrat, Fachbereichsrat, Studierendenparlament and briefly as a member of the Academic Senate, before retiring from student life.

A number of open source projects are hosted all over the place at

and you can reach me in the Fediverse over

as well as read my blog over at


Introduction to C Programming
Leo (he/his) || Janis (she/her) || * (they/them)

In this workshop you will learn C through many hands on exercises of varying difficulty or bring-your-own projects. Everyone will be learning on their own time, the only requirement is motivation! Groups welcome as well, and if you already started a small project I can also provide you a small review and perhaps ideas on how to improve.

The platform will be mostly Linux and UNIX/POSIX (BSD, macOS, Solaris) due to personal experience there, but Windows is possible as well (with a bit more limited help). Alternatively the Windows Subsystem for Linux can be used to develop and target Linux from Windows.

Workshop - E.T.I.
HDMI (room 3)
Future Proofing my Printer with Reversing
Leo (he/his) || Janis (she/her) || * (they/them)

My printer is only supported through proprietary drivers using a custom CUPS filter to convert PDFs/Images/... into a printer-specific Page Description Language such as PJL or PCL. However, CUPS is to deprecate filter based printer drivers in favor of IPP which every new printer supports. Mine doesn't. However, CUPS/OpenPrinting have designed PAPPL, a library to turn old printer filters/drivers into "Printer Applications". These are self-contained (and thus sandboxable) small daemons that provide an IPP server on localhost for applications to interface with, and spit out the commands necessary to talk to the printer in question. My goal is to write such a printer application for my printer. I havehad no previous knowledge of printing in general and on Linux and UNIX/macOS specifically, so this is taking rather long (and is by no means finished).

HDMI (room 3)