Edward Snowden's phone case will tell you if you're being tracked

Edward Snowden has secretly been working on a project to stop smartphones from revealing the location of people in dangerous places.
Snowden said he envisions it as a protection for journalists and human rights workers, but it could be used by anyone who doesn’t want to be spied on.

On Thursday, the ex-NSA whistleblower unveiled his plans to build a revolutionary iPhone 6 case. It doesn’t block cell phone signals, but it does make sure the device stops transmitting data when you put it on “airplane mode.”
Most people think that “airplane mode” pulls a smartphone off the grid. It doesn’t. On the latest iPhones, for example, the device still transmits GPS signals when it’s in “airplane mode.”
Governments can take advantage of that by hacking phones. (That’s how the NSA can “turn on” your phone remotely.)
They expect to develop a prototype of this case in the next year. But don’t get your hopes up. This is a tiny, experimental effort.