Hi there, and welcome to my personal website.

I'm jaseg, and I write about my projects here. You can find long-form articles in the blog, and links to my open-source projects on the projects page. On the top right of this page, there are links to my git repositories and social media pages. If you want to learn more about me, head over to the about page.

Recently updated projects


KiMesh is a KiCad plugin that automatically creates security meshes with two or traces covering an arbitrarily-shaped outline on the board.

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8seg is an experimental textual display. It is made from a 45m by 1.5m large lacework banner that can be put up in a variety of spaces, conforming to the space's size and shape through bending and folding.

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8seg Technical Overview Prologue German hacker culture has this intense love for things that light up in colorful ways. Like for many others in this community, I have always been fascinated by LEDs. One of the first things on my pile of unfinished projects was to build my own LED matrix and use it to display text. When I started that project, I was still new to electronics. Back then, commercial LED matrices were limited to red or green color only, and were very expensive, so there was an incentive to build your own. Read more

Ubiquiti EdgeRouter on Deutsche Telekom GPON Fiber

Disclaimer I provide this guide as a reference for other knowledgeable users without any warranty. Please feel free to use this as a resource but do not hold me responsible if this does not work for you. There is a significant chance that due to an error on my side or due to Telekom changing their setup this guide will not work for you, and you may end up having to pay for an unsuccessful Telekom technician visit. Read more

New Paper on Inertial Hardware Security Modules

World's First DIY HSM Last week, Prof. Dr. Björn Scheuermann and I have published our first joint paper on Hardware Security Modules. In our paper, we introduce Inertial Hardware Security Modules (IHSMs), a new way of building high-security HSMs from basic components. I think the technology we demonstrate in our paper might allow some neat applications where some civil organization deploys a service that no one, not even they themselves, can snoop on. Read more

Kicad Mesh Plugin

Tamper Detection Meshes Cryptography is at the foundation of our modern, networked world. From email to card payment infrastructure in brick and mortar stores, cryptographic keys secure almost every part of our digital lives againts cybercriminals or curious surveillance capitalists. Without cryptography, many of the things we routinely do in our lives such as paying for groceries with a credit card, messaging a friend on Signal or unlocking a car with its keyfob would not be possible. Read more

Private Contact Discovery

Private Contact Discovery Private Contact Discovery (PCD) is the formal name for the problem modern smartphone messenger applications have on installation: Given a user's address book, find out which of their contacts also use the same messenger without the messenger's servers learning anything about the user's address book. The widespread non-private way to do this is to simply upload the user's address book to the app's operator's servers and do an SQL JOIN keyed on the phone number field against the database of registered users. Read more

Hardware Security Module Basics

Hardware Security Modules and Security Research and Cryptography On May 17 2019 I gave a short presentation on the fundamentals of hardware security modules at the weekly seminar of Prof. Mori's security research working group at Waseda University. The motivation for this was that outside of low-level hardware security people and people working in the financial industry HSMs are not thought about that often. In particular most network or systems security people would not consider them an option. Read more

How to talk to your microcontroller over serial

Scroll to the end for the TL;DR. In this article I will give an overview on the protocols spoken on serial ports, highlighting common pitfalls. I will summarize some points on how to design a serial protocol that is simple to implement and works reliably even under error conditions. If you have done low-level microcontroller firmware you will regularly have had to stuff some data up a serial port to another microcontroller or to a computer. Read more

Thor's Hammer

In case you were having an inferiority complex because your friends' IBM Model M keyboards are so much louder than the shitty rubber dome freebie you got with your pc... Here's the solution: Thor's Hammer, a simple typing cadence enhancer for PS/2 keyboards. Your browser does not support the HTML5 video tag. A demonstration of the completed project. h264 download / webm download The connects to the keyboard's PS/2 clock line and briefly actuates a large solenoid on each key press. Read more

32-Channel LED tape driver

Theoretical basics Together, a friend and I outfitted the small staircase at Berlin's Chaos Computer Club with nice, shiny RGB-WW LED tape for ambient lighting. This tape is like regular RGB tape but with an additional warm white channel, which makes for much more natural pastels and whites. There are several variants of RGBW tape. Cheap ones have separate RGB and white LEDs, which is fine for indirect lighting but does not work for direct lighting. Read more

Wifi Led Driver

Project motivation The completed driver board installed in the 3D-printed case. This device can now be connected to 12V and two segments of LED tape that can then be controlled trough Wifi. The ESP8266 module goes on the pin header on the left and was removed for this picture. After the multichannel LED driver was completed, I was just getting used to controlling LEDs at 14-bit resolution. I liked the board we designed in this project, but at 32 channels it was a bit large for most use cases. Read more