This is a private blog by Jens Lechtenbörger.

Jens Lechtenbörger

OpenPGP key: 0xA142FD84
(What is OpenPGP? Learn how to protect your e-mail.)

Creative Commons License
Unless explicitly stated otherwise, my posts on this blog are licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

Certificate Pinning for GNU Emacs

GNU Emacs is where is spend most of my computer time. Using Emacs, I’m writing texts in general and this post in particular, I’m programming, I’m reading RSS feeds and news articles, I’m reading and writing e-mails. Emacs is highly customizable and extensible which is great, in general. However, in the past Emacs valued convenience […]

Certificate Pinning with GnuTLS in the Mess of SSL/TLS

Lots of modern communication is “protected” from spying eyes and other criminals via an Internet standard called Transport Layer Security (TLS) or its outdated predecessor Secure Sockets Layer (SSL). In the following, I’m using the term “SSL/TLS” to refer to both of them. In a nutshell, SSL/TLS is a mess. It’s security has been, can […]

My Fairphone and I Love Free Software

Some time ago I recommended the crowdfunding campaign to produce the Fairphone. In early January my Fairphone arrived, and I’m still experimenting a lot, but I’d like to share initial ideas on what software I did (not) install. I love free software, and I did not install anything but free software.

The Fairphone is […]

OpenPGP and S/MIME or Trust and “Trust”

OpenPGP and S/MIME are competing standards for e-mail encryption, and I argue that Alice and Bob should go for OpenPGP if they are in doubt what standard to prefer. Essentially, the “trust” model of S/MIME is fundamentally flawed.

I’m using both, OpenPGP and S/MIME, and I wrote a GNU Emacs library for automatic encryption of […]

How I select Tor guard nodes under global surveillance

I’m trying to protect my privacy on the Net, and for years I have been using and advocating (in German) the anonymization tools JonDonym and Tor towards that end. Before you continue reading, please be warned that I’m an anonymization hobbyist. There are ongoing discussions on the tor-talk mailing list concerning network diversity and the […]

FairPhone starting a movement

Currently, our phones are stained with blood, literally, as exemplified by the well-known Foxconn suicides or the less well-known role of conflict minerals to sustain war and murder in Congo. FairPhone is an endeavor to produce smartphones in a fairer way, and after three years of preparatory work, the Dutch start-up just started its pre-order […]

How to set up your Fellowship card

The FSFE Fellowship Card is an OpenPGP smartcard to hold GnuPG signature, encryption, and authentication keys. The fundamental idea of OpenPGP smartcards is to store your key material securely on the card, where all cryptographic operations are executed, maybe after entering the card’s PIN. Thus, secret keys never leave the card. [Note that without smartcards […]

Ubuntu search still broken in 13.04 beta

What GNU/Linux distribution do you recommend to your friends?

Friends with neither much knowledge about nor interest in computers, who just want a machine that works?

Ubuntu is supposed to be a particularly user-friendly GNU/Linux distribution, and I’ve been using various versions of Ubuntu for several years, although I’m aware that it is not endorsed […]