MAC address de-randomization for WiFi device counting: Combining temporal- and content-based fingerprints

addresses over time so that not a single fixed address is used that may identify a specific user. This has the consequence that it is not even possible to extract anonymous information on people mobility by analyzing WiFi traffic traces, which would be useful for many purposes (e.g., counting the number of people in a mass transport vehicle).To address this issue, in this paper we propose a novel MAC address de-randomization algorithm which groups specific messages (i.e., the Probe Requests) generated by the same physical device. With respect to past works, we consider a combination of the features that have been previously considered in isolation, which are associated to the content and length of the optional fields conveyed in the sent frames and the rate at which the frames are numbered over time. These features are then used by density-based