MSP: Providing location privacy in WLAN networks with a MAC Swapping Protocol

Location privacy has been widely studied in the context of location-based services (LBS). However, a far more serious location privacy threat arises when malicious eavesdroppers listen to wireless transmissions from an unsuspecting mobile user in order to pinpoint his location and figure out his identity. This new scenario is known as location estimation (LE). While there are several strategies to mitigate the threats posed by LBS scenarios, only a few researchers deal with countermeasures for LE scenarios. This paper proposes MSP, a MAC Swapping Protocol that allows two mobile users to discreetly exchange their MAC addresses without malicious eavesdroppers being able to detect it. In this way, although potential eavesdroppers can still pinpoint the location of a transmitting node, they will get its identity wrong. Over time, MSP eliminates the eavesdroppers' ability to link the position and identity of a transmitting source. In contrast to related research, the identity exchange in MSP takes into account information from the mobile users' physical and MAC layers simultaneously, so an attack in one layer does not expose the identity exchange in the other layer. In order to provide location privacy, MSP uses two algorithms. The first algorithm works at the physical layer, allowing two mobile nodes to decide when and where to exchange their MAC addresses. The second algorithm uses virtual interfaces to guarantee that the identity exchange does not exhibit any abnormal behavior at the MAC layer. Test-bed and simulation experiments demonstrate that MSP is able to guarantee location privacy even with attackers eavesdropping at the physical and MAC layers simultaneously.