*3.2. Adversary Model*

We assume a Global Passive Adversary (GPA) in this work. The detail of the adversary model is shown in Figure 3. The aim of the GPA is to track various locations to identify the journeys of a target vehicle in the network. In this model, we make various assumptions about the GPA. The GPA can deploy a low-cost radio transceiver to intercept broadcast beacon messages in the region of interest. The contents of the beacon message are pseudoidentity, speed, location, direction, and other headings. The adversary can capture a large portion of the network to catch the messages exchanged between vehicles. It can track the various locations of a vehicle with the help of eavesdropping vehicle communication [22]. It also has the ability to capture the pseudonyms of vehicles and can link the various pseudonyms of a vehicle used during a trip. The adversary captures beacon messages to try to correlate the old pseudonym with the newly changed pseudonym. By matching the different pseudonyms of a vehicle at different locations, the adversary gets knowledge of the target vehicle's behavior and could predict a vehicle's future locations.

**Figure 3.** Adversary model.
