Wi-Fi network could recognize who you are even if you turn off your phone

When you buy through links on our articles, Future and its syndication partners may earn a commission.

• Ordinary Wi-Fi networks can reportedly identify people without cameras or consent

• KASTEL researchers achieved nearly 100% identification accuracy across 197 volunteers tested

• Wi-Fi signals can reportedly reveal people from different viewing angles

A new study suggests that ordinary Wi-Fi networks could be repurposed to identify individuals without cameras, sensors, or their knowledge or consent.

Researchers from KASTEL, the Institute of Information Security and Dependability at KIT, tested the approach on 197 volunteers in controlled conditions.

Their system reportedly achieved nearly 100% identification accuracy regardless of a person's viewing angle or the way that person walked.

A method that needs no extra hardware

The technique relies on beamforming feedback information, a type of signal that connected devices routinely send back to a router.

This information is transmitted without any encryption, meaning anyone within range of the network could potentially intercept and read it.

By analyzing these radio signals over time, the system reportedly builds images of people from multiple viewpoints inside a space.

Earlier wireless sensing methods often required specialized equipment, such as LIDAR sensors or detailed measurements of channel state information from a network.

By contrast, the researchers say a standard, unmodified Wi-Fi device is entirely sufficient to carry out this new identification process.

"By observing the propagation of radio waves, we can create an image of the surroundings and of persons who are present," said Thorsten Strufe, a professor at KASTEL, KIT's Institute of Information Security and Dependability.

"This works similar to a normal camera, the difference being that in our case, radio waves instead of light waves are used for the recognition.

A user does not need to carry a phone, smartwatch, or other Wi-Fi-enabled device for the system to work.

Turning off one's own device would reportedly not prevent identification, since other active Wi-Fi devices nearby could still be used.

Privacy concerns extend beyond conventional surveillance

The researchers argue that widespread wireless networks could create privacy concerns because they operate throughout homes, offices, restaurants, cafés, and other public environments.

Felix Morsbach noted that intelligence agencies and cybercriminals already have simpler methods, including compromising CCTV systems and connected video doorbells.

"The omnipresent wireless networks might become a nearly comprehensive surveillance infrastructure with one concerning property: they are invisible and raise no suspicion," Morsbach added.

Compared with existing surveillance options, such as CCTV footage or connected video doorbells, wireless signals leave no visible trace behind.

Professor Strufe cautioned that this same invisibility could make the technology particularly attractive within certain authoritarian political systems around the world.

"The technology is powerful, but at the same time entails risks to our fundamental rights, especially to privacy," said Strufe.

Ordinary routers could potentially enable people to be recognized without their knowledge during routine movements, and this could be dangerous in the wrong hands.

Therefore, widespread deployment could make individual encounters difficult to distinguish from ordinary wireless activity.

The researchers argue that privacy safeguards should be incorporated into Wi-Fi technology before such capabilities become widely and easily exploited.

Specifically, they are calling for protections to be written into the forthcoming IEEE 802.11bf wireless standard currently under active development.

Via ScienceDaily