I blamed my router for poor Wi-Fi until I realized where I'd placed the second one

Researchers from KASTEL, a university institute in Germany, have developed a method that could potentially identify individuals using ordinary Wi-Fi routers without their knowledge or consent. This technique relies on a feature called beamforming, which routers commonly use to optimize wireless signal quality. The researchers tested their system on 197 volunteers in controlled conditions and found it achieved nearly 100% identification accuracy, regardless of a person's viewing angle or movement.

The method uses radio signals transmitted by devices connected to the Wi-Fi network, which are sent without encryption and could be intercepted by anyone within range. The researchers argue that turning off an individual's own Wi-Fi-enabled device would not prevent identification, as other active devices nearby could still be used.

While this technology relies solely on standard Wi-Fi routers, it could pose significant privacy concerns as many networks operate in public spaces like homes, offices, and restaurants. The authors, including Professor Thorsten Strufe, warn that this type of surveillance could be attractive to authoritarian governments due to its covert nature, and they are calling for the upcoming IEEE 802.11bf wireless standard to include safeguards to prevent its misuse.