Uh oh! Public Wi-Fi routers can 'identify' you even if you have no phone

Here’s an unsettling development in this episode of “everyday tech can do things you probably never imagined”: in the future, anyone who regularly walks past a café or restaurant with public Wi-Fi could be identified—even without a smartphone in their pocket.

Researchers at Karlsruhe Institute of Technology (KIT) have discovered that commercially available Wi-Fi routers can recognize and identify individual people based on signal changes. All that’s required is for other devices in the vicinity to be connected to the router.

Professor Thorsten Strufe from KASTEL—the Institute of Information Security and Dependability at KIT— explains that the propagation of Wi-Fi radio waves can be used to create an image of the router’s physical environment and the people in it. This works in a simila