There is a constant arms race between law enforcement and criminals, especially when it comes to technology. For years, law enforcement has been frustrated with encrypted messaging apps, like Signal and Telegram. And law enforcement has been even more frustrated by encrypted phones, specifically designed to thwart authorities from snooping.

But in 2018, in a story that seems like it's straight out of a spy novel, the FBI was approached with an offer: Would they like to get into the encrypted cell phone business? What if they could convince criminals to use their phones to plan and document their crimes — all while the FBI was secretly watching? It could be an unprecedented peek into the criminal underground.

To pull off this massive sting operation, the FBI needed to design a cell phone that criminals wanted to use and adopt. Their mission: to make a tech platform for the criminal underworld. And in many ways, the FBI's journey was filled with all the hallmarks of many Silicon Valley start-ups.

On this show, we talk with journalist Joseph Cox, who wrote a new book about the FBI's cell phone business, called Dark Wire. And we hear from the federal prosecutor who became an unlikely tech company founder.

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