Barnaby first gained prominence when he hacked into an ATM machine and made it spit out cash. Colleagues said he was one of the good guys.

Chris Valasek and Charlie Miller have been hacking into products for a long time. But they don't steal stuff or mess with people; instead, their purpose is to pressure companies into making their products more secure. Their recent research on hacking cars has shown just how dangerous these kinds of attacks could be.

A group of good guy hackers showed us how they can listen in on phone conversations and read text messages of Verizon customers simply by using inexpensive store bought technology.

One of the world's largest and most open gatherings of hackers is asking federal workers to skip this year's event. "Our community operates in the spirit of openness, verified trust, and mutual respect," the founder of the Def Con conference says.