Recently, a team from the Karlsruhe Institute of Technology in Germany released research showing that people can be accurately identified and tracked using Wi-Fi signals alone, without the need for the identified subject to carry a mobile phone or computer. The discovery sparked a new round of discussions about privacy and surveillance.
The research team proposed that any router that supports Wi-Fi 5 (802.11ac) and above can use beamforming technology to generate radio "images" to track human body features from multiple angles. The technology is named BFId, which stands for "Wireless Identity Inference Attack." Unlike traditional software security measures that rely on devices, this solution directly identifies the person itself. When combined with a machine learning model, the identification can be completed within a few seconds, with an accuracy of almost 100%. During the study, the team successfully tracked 197 participants. Regardless of their activity methods and detection angles, the recognition effect was not affected.
It’s worth noting that Wi-Fi signals are often unencrypted, so anyone within coverage can access relevant identifying information. Currently, most popular devices support Wi-Fi 5 and above standards, which means that identification technology similar to BFId can theoretically be deployed in most places. Privacy protection experts warn that in the future, this technology may be used by governments, malicious organizations, etc. for secret and efficient human identification and monitoring.
Similar solutions are also being explored internationally. Sapienza University in Rome, Italy, this year launched WhoFi technology, which uses human body interference on Wi-Fi signals to identify individuals. With the help of deep learning models, the identification accuracy rate exceeds 90%. There have been previous experimental results using Wi-Fi to recognize gestures and even partition walls.
The spread of this technology will bring new legal and ethical challenges. For example, in early 2025, the city of New Orleans revealed a large-scale secret operation related to artificial intelligence surveillance, which lasted for two years without being informed to the public. Wi-Fi identification methods like BFId and WhoFi can bypass existing laws related to facial recognition and make supervision passive.
As wireless identification and monitoring capabilities increase, there is greater pressure to protect personal privacy and data security. Experts call for the establishment of regulations and defense systems for new Wi-Fi identification technologies as soon as possible to reduce the risks that come with it.