On the Implementation of Location Obfuscation in openwifi and Its Performance

Abstract

Wi-Fi sensing as a side-effect of communications is opening new opportunities for smart services integrating communications with environmental properties, first and foremost the position of devices and people. At the same time, this technology represents an unprecedented threat to people's privacy, as personal information can be collected directly at the physical layer without any possibility to hide or protect it. Several works already discussed the possibility of safeguarding users' privacy without hampering communication performance. Usually, some signal pre-processing at the transmitter side is needed to introduce pseudo-random (artificial) patterns in the channel response estimated at the receiver, preventing the extraction of meaningful information from the channel state. However, there is currently just one implementation of such techniques in a real system (openwifi), and it has never been tested for performance. In this work, we present the implementation of a location obfuscation technique within the openwifi project that enables fine manipulation of the radio signal at transmitter side and yields acceptable, if not good, performance. The paper discusses the implementation of the obfuscation subsystem, its performance, possible improvements, and further steps to allow authorized devices to "de-obfuscate" the signal and retrieve the sensed information.

Integrating CSI Sensing in Wireless Networks: Challenges to Privacy and Countermeasures

“…This approach is very interesting but cannot work on-line (since the CSI is computed per-packet in realtime), and the problem of preserving communication performance is not explicitly addressed in the paper. A different approach to CSI obfuscationbut with a focus also on standard-compatibility and communication performance-is described in [8]- [10], in which different flavors of random CSI distortions are proposed and analyzed. The standardcompliance is proven by a working implementation of the proposed system in [10].…”

“…A different approach to CSI obfuscationbut with a focus also on standard-compatibility and communication performance-is described in [8]- [10], in which different flavors of random CSI distortions are proposed and analyzed. The standardcompliance is proven by a working implementation of the proposed system in [10].…”

“…Indeed, such a solution is technologically mature and it can easily be embedded into standards, possibly with a proper protocol that allows sensing by legitimate actors by inverting the O(f, t) function. We presented a working prototype of the system and a discussion on a protocol to allow legitimate sensing in presence of obfuscation in [10]. The implementation only requires some little additional area on the original FPGA design and does not require transmitting any additional information.…”