If you were scared by the thought of the NSA listening in on your phone calls and parsing through your personal emails, prepare to be unnerved. Students at MIT are working on a system that allows snoopers to see through walls using only a Wi-Fi connection.
“Wi-Fi signals are typically information carriers between a transmitter and a receiver,” begins the study’s abstract. “In this paper, we show that Wi-Fi can also extend our senses, enabling us to see moving objects through walls and behind closed doors. In particular, we can use such signals to identify the number of people in a closed room and their relative locations. We can also identify simple gestures made behind a wall, and combine a sequence of gestures to communicate messages to a wireless receiver without carrying any transmitting device.”
The people behind the study see many useful and not creepy applications of such a technology.
“Law enforcement personnel can use the device to avoid walking into an ambush, and minimize casualties in standoffs and hostage situations,” the authors point out. “Emergency responders can use it to see through rubble and collapsed structures. Ordinary users can leverage the device for gaming, intrusion detection, privacy-enhanced monitoring of children and elderly, or personal security when stepping into dark alleys and unknown places.”
The paper, penned by MIT’s Fadel Adib and Dina Katabi, calls their invention Wi-Vi. Basically, it “listens in” on a Wi-Fi router in another room. It reads the radio waves emitting from the router (it doesn’t require a password) and blasts the room with its own directionless waves. Measuring these two waves and using the static location of the router, the Wi-Vi unit can detect bodies in the space and their movement—even through thick walls and doors.
“Wi-Vi can detect objects and humans moving behind opaque structural obstructions,” the authors continue. “This applies to 8-inch concrete walls, 6-inch hollow walls, and 1.75-inch solid wooden doors. A Wi-Vi device pointed at a closed room with 6-inch hollow walls supported by steel frames can distinguish between 0, 1, 2, and 3 moving humans in the room.”
It’s still a far cry from the X-ray scanners the TSA uses, but it’s a startling new step in surveillance.