I am a german computer security professional. In this field I have given numerous speeches, the most well-known ones about Security Enhanced Linux. I've also published a fairly famous paper on Internet worms. My current interest is the interface between computer security and humans, especially users (touching on HCI and psychology).
I have been active as a civil rights activits close to the EFF and FSF here in Europe and was deeply involved in the DeCSS affair.
I am also a game designer and hobby cryptographer.