Wi-Fi Localization Obfuscation: An implementation in openwifi

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, using signal pre-processing at the transmitter side to introduce pseudo-random (artificial) patterns in the channel response estimated at the receiver, preventing the extraction of meaningful information from the channel state, a process called obfuscation. One step beyond the proof-of-concept for obfuscation feasibility, is its implementation in working systems. 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 system has been implemented for both 802.11a/g/h and 802.11n systems, including MPDU aggregation, while implementation for 802.11ac or ax is still not feasible because openwifi does not support 40MHz channelization and beyond. This contribution 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.