Wi-Fi can detect individuals’ identities without phones or gadgets, says study
Radio wave imaging rivals cameras in tracking movement and posture
Silent surveillance via everyday routers will further erode individual privacy
Imagine walking past your favourite cafe every morning. You never log into their Wi-Fi, never pull your phone out. And yet, without your knowledge, your body shape has been tracked, how you walk has been analysed, and your identity determined with near-perfect accuracy.
SurveyThat’s not a James Bond movie gadget or mindless sci-fi dystopia. That’s wireless networking in 2025.
Last week, researchers at Germany’s Karlsruhe Institute of Technology (KIT) published findings that suggest Wi-Fi networks – yes, the same one that powers your video calls and late-night streaming binges – can be used to identify people in real-time without any device on them. No smartphone in your pocket, no smartwatch on your wrist. Just your body subtly interrupting radio signals. If that isn’t scary enough from a privacy, safety and security perspective.
BFI: Beamforming feedback information
At the heart of this breakthrough is something called beamforming feedback information (BFI) – a technical term for how Wi-Fi routers and devices tune signals for optimal performance. What the KIT team discovered is that by monitoring this data, they could create silhouettes, postures, even movement signatures – what lead researcher Professor Thorsten Strufe describes as camera shots made not of light, but of radio waves.
But what’s even more startling? This works regardless of whether a person is carrying a connected device or not.
Julian Todt, a cybersecurity expert from KIT’s KASTEL lab, took it one step further suggesting how every Wi-Fi router could potentially be used for surveillance. The router at your local gym, your office, or your neighbor’s home might be silently tracking who comes and goes – not by intent, necessarily, but because the capability is now demonstrably real.
Wi-Fi based tracking is real: Enter WhoFi
This isn’t the first time researchers have pointed out how Wi-Fi might evolve from passive network infrastructure into an active surveillance tool. Back in September, Earth.com profiled WhoFi, a research project out of Sapienza University of Rome.
While KIT’s work draws its power from standard off-the-shelf Wi-Fi devices and beamforming data, WhoFi takes a slightly more technical path, analyzing Channel State Information (CSI) – the radio signal distortions caused when your body moves through a room.
Both systems, however, converge on the same unsettling truth that your physical presence alters radio signals in uniquely identifiable ways.
In controlled lab tests, WhoFi’s deep learning models identified individuals with 95.5% accuracy. KIT’s team clocked near-perfect results from just seconds of signal observation. No cameras or consent needed.
Privacy repercussions of Wi-Fi based surveillance
Let’s pause for a second. Your wireless router is supposed to beam you Netflix, not betray your physical presence. Yet as Wi-Fi becomes smarter – more tuned, more spatially aware – it’s crossing an invisible line.
The promise of these systems lies in safety and convenience. Fall detection in elder care, for instance. Security systems that don’t need cameras. Intrusion detection in factories. But that same tech, in the wrong hands, offers an eerily powerful tool for location tracking, movement monitoring, and yes – personal identification.
Unlike facial recognition, which has legal precedent and growing public awareness, these Wi-Fi-based techniques sidestep current surveillance laws. They don’t “see” you in the traditional sense, so they operate in a legal grey zone.
What’s truly scary is that for this Wi-Fi based surveillance to work there’s no need for any specialized hardware. This isn’t a spy agency installing custom rigs on utility poles. It’s a potential exploit of the consumer-grade router you picked up during a Diwali sale.
Intelligence agencies or cybercriminals have easier, more invasive tools – like CCTV or hacked smart doorbells. But the difference here with Wi-Fi based surveillance is the instant unprecedented scale it offers. There are billions of Wi-Fi-enabled devices in homes and public spaces, and it’s not far-fetched to imagine a future where passive Wi-Fi monitoring becomes part of a broader surveillance web – especially when machine learning makes it ridiculously easy.
Both the KIT and WhoFi teams stress that their projects are academic – designed to spark conversation and policy, not fear. But as more Wi-Fi routers gain beamforming and CSI capabilities, the line between network utility and biometric surveillance continues to blur. And when everything around us starts to become a sensor, how much room is left for privacy?
Follow Us
Jayesh Shinde
Executive Editor at Digit. Technology journalist since Jan 2008, with stints at Indiatimes.com and PCWorld.in. Enthusiastic dad, reluctant traveler, weekend gamer, LOTR nerd, pseudo bon vivant. View Full Profile
