The homepage of Jan Hrach

I work as Linux administrator, I create embedded designs and I write software (preferably lowlevel, parallel, respecting the UNIX philosophy, from the field of signal processing, networks or cryptography). I can quickly introduce myself into almost any programming language or technology and produce drafts of seemingly impossible things. You can find some of my projects below.

I have a bachelor degree from General Computer Science (thesis) and I am currently studying master program Software and data engineering on Charles University. I am an active member of brmlab, the best hackerspace in Prague. Though I'm a "computers guy" by profession, my interests are much broader, including everything from biology over physics to engineering.

I ride bike as the only mean of commuting everyday. Once a while I go to a longer biketrip too. You can join me if you wish :)


A5/1 cracker accelerated with OpenCL


network-transparent SDR software


a live video streamer


GSM sniffing and decoding toolkit


The fastest channelizer in Litoměřice!


realtime the entire Tetra network!

My articles

AbcLinuxu (Czech) - Linux, OpenSource, security (Czech) - Bitcoin, computer security

KP (Czech) - civil rights advocacy

My talks (in Czech)

Misc. user page - lots of useful tips and code snippets

Videoserver - recordings of various lectures

More code!






I contribute to:


decode metadata and maybe more




You can talk to me in Czech, Slovak or English.

OpenPGP key, fingerprint CD98 5440 4372 0C6D 164D A24D F019 2F8E 6527 282E.

  • E-mail: jenda .a. hrach ... eu.
  • Jabber: hrachj .a. abclinuxu ... cz, hrachj .a. jabber ... cz, OTR FP
  • IRC: Jenda` on #brmlab on freenode
  • Bitcoin: 1JENDAF7MncjqE3nPA1Zzqh85WJhvdpSwX
  • HAM: OK1DNA in JO70FB (sometimes idling on OK0N, but not really often)
  • IČ (czech tax identification number): 887 88 954
  • Phone: +420 737 660 630. Please note that phone eavesdropping is a common practice in my country (well, as you have seen above, I have even worked on a GSM eavesdropper :). Additionaly, as location data are routinely sold by Czech operators, I often leave my phone at home.
  • SIP (usually offline): 910114502, ZRTP is supported.