Drones That See Through Walls Are Just the Latest Trick for Wi-Fi Vision

They can also read your passwords

Drones armed with wi-fi antennas can see through walls.

The results of the latest experiment from electrical engineering researchers at University of California Santa Barbara don’t suggest celebrities need to fear a new flying robot paparazzi quite yet, but with a little work these findings could be great for thieves, soldiers and corporate spies.

Yasamin Mostofi and Chitra R. Karanam built a very short square housing of brick, with a smaller, very simple stone structure inside. The inner structure had the shape of a box with a smaller box sitting on top of it. After scanning it with two drones (one sending a wi-fi signal and the other receiving), computers were able to process their measurements and come up with something that looked more like two cylinders, sitting one on top of the other.

Illustration from the researchers’ work. UCSB

Not bad, but not amazing. Now that they know it’s possible, they can refine it much further. Early cameras weren’t that great, either, and now we take photos of people from space.

This is hardly the first time wi-fi has been used to intuit rough visual information. In terms of energy, wi-fi is just low intensity microwaves. It isn’t especially different from of light, except our eyes weren’t built to measure it. That doesn’t mean electronic equipment can’t.

Prof. Mostofi has herself done previous experiments. In 2014, she got a hazier picture through walls with ground-based robots armed with wi-fi. In 2015, she demonstrated that wi-fi could be used to count the number of people in a space.

In 2015, MIT researchers were able to see people through a wall using a wi-fi signal, as The Verge reported. They couldn’t make out their faces or anything, but it’s pretty amazing that some James Bond application of this hasn’t shown up in an action movie (if it has, hit me up on Twitter—I have some free time this weekend).

That’s not the craziest one, though. Last year, researchers at the University of Michigan and Nanjing University used off-the-shelf wi-fi devices to construct a keystroke logger. In short, they shot a wi-fi signal across a keyboard and were able to interpret the received signal in such a way that they could identify keystrokes with 95 percent accuracy.

It’s actually even easier to detect keystrokes if a spy can record the sound. Remember that scene in either the documentary Citizenfour or the movie Snowden when Edward Snowden (person or character, respectively) puts the blanket over his head when he types his passwords? That’s why.

Drones That See Through Walls Are Just the Latest Trick for Wi-Fi Vision