Koum and Acton share a long history in computer security. They first met at Yahoo while doing a security audit for the company. During this time, Koum was also part of a seminal security collective and think tank called w00w00 (pronounced “whoo whoo”), a tight online community that used the old IRC chat service to trade ideas related to virtually any aspect of the field. Koum grew up in the Ukraine under Soviet rule before immigrating to the US as a teenager, so he has some intimate familiarity with the challenges of maintaining privacy in the face of an intrusive government. But Koum says that the bigger force behind encrypting WhatsApp was Acton, a comparatively outgoing individual who grew up in Florida. “Brian gets a lot of credit for wanting to do it earlier,” Koum says of WhatsApp encryption.