If you're reading this, the web server was installed correctly.™

I work as Linux administrator, webmaster, I create embedded designs and I write software (preferably lowlevel, parallel, respecting the UNIX philosophy, from the field of signal processing, networking 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 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


SDR software that sucks less


a live video streamer


GSM sniffing and decoding toolkit


The fastest channelizer in Litoměřice!

OpenWRT hacking

OpenWRT and Debian crossarch fun

My articles

AbcLinuxu (Czech) - Linux, OpenSource, security

Root.cz (Czech) - Bitcoin, computer security

KP (Czech) - civil rights advocacy

My talks


brmlab.cz user page - lots of useful tips and code snippets

Videoserver - recordings of various lectures

More code!






I contribute to:


realtime the entire Tetra network!


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, 411859@sip.odorik.cz. ZRTP is supported.