In three years or so, the Wi-Fi specification is scheduled to get an upgrade that will turn wireless devices into sensors capable of gathering data about the people and objects bathed in their signals.
“When 802.11bf will be finalized and introduced as an IEEE standard in September 2024, Wi-Fi will cease to be a communication-only standard and will legitimately become a full-fledged sensing paradigm,” explains Francesco Restuccia, assistant professor of electrical and computer engineering at Northeastern University, in a paper summarizing the state of the Wi-Fi Sensing project (SENS) currently being developed by the Institute of Electrical and Electronics Engineers (IEEE).
SENS is envisioned as a way for devices capable of sending and receiving wireless data to use Wi-Fi signal interference differences to measure the range, velocity, direction, motion, presence, and proximity of people and objects.
It may come as no surprise that the security and privacy considerations of Wi-Fi-based sensing have not received much attention.
As Restuccia warns in his paper, “As yet, research and development efforts have been focused on improving the classification accuracy of the phenomena being monitored, with little regard to S&P [security and privacy] issues. While this could be acceptable from a research perspective, we point out that to allow widespread adoption of 802.11bf, ordinary people need to trust its underlying technologies. Therefore, S&P guarantees must be provided to the end users.”
“Indeed, it has been shown that SENS-based classifiers can infer privacy-critical information such as keyboard typing, gesture recognition and activity tracking,” Restuccia explains. “Given the broadcast nature of the wireless channel, a malicious eavesdropper could easily ‘listen’ to CSI [Channel State Information] reports and track the user’s activity without authorization.”
And worse still, he argues, such tracking can be done surreptitiously because Wi-Fi signals can penetrate walls, don’t require light, and don’t offer any visible indicator of their presence.
Restuccia suggests there needs to be a way to opt-out of SENS-based surveillance; a more privacy-friendly stance would be to opt-in, but there’s not much precedent for seeking permission in the technology industry.