# Virtual Pseudonym-Changing and Dynamic Grouping Policy for Privacy Preservation in VANETs
###### Abstract  
Location privacy is a critical problem in the vehicular communication networks. Vehicles broadcast their road status information to other entities in the network through beacon messages. The beacon message content consists of the vehicle ID, speed, direction, position, and other information. An adversary could use vehicle identity and positioning information to determine vehicle driver behavior and identity at different visited location spots. A pseudonym can be used instead of the vehicle ID to help in the vehicle location privacy. These pseudonyms should be changed in appropriate way to produce uncertainty for any adversary attempting to identify a vehicle at different locations. In the existing research literature, pseudonyms are changed during silent mode between neighbors. However, the use of a short silent period and the visibility of pseudonyms of direct neighbors provides a mechanism for an adversary to determine the identity of a target vehicle at specific locations. Moreover, privacy is provided to the driver, only within the RSU range; outside it, there is no privacy protection. In this research, we address the problem of location privacy in a highway scenario, where vehicles are traveling at high speeds with diverse traffic density. We propose a Dynamic Grouping and Virtual Pseudonym-Changing (DGVP) scheme for vehicle location privacy. Dynamic groups are formed based on similar status vehicles and cooperatively change pseudonyms. In the case of low traffic density, we use a virtual pseudonym update process. We formally present the model and specify the scheme through High-Level Petri Nets (HLPN). The simulation results indicate that the proposed method improves the anonymity set size and entropy, provides lower traceability, reduces impact on vehicular network applications, and has lower computation cost compared to existing research work. v 2021 21 February 2021 2 21 28 April 2021 The basic technological elements that compose vehicular networks are sensors, radar, cameras, On-Board Units (OBU), Event Data Recorders (EDR), Global Positioning System (GPS), and omnidirectional antennas [5]. An OBU facilitates communication between one vehicle and other vehicles and road infrastructure. An EDR records all the communication events that occurred during a vehicle trip. Precise location coordinates are accessed and updated with the help of GPS. Radar and sensors indicate various types of obstacles and dangerous situations on the road. A tamper-proof device can be installed in the OBU to protect confidential vehicle information from an outsider attacker. The communication models of VANETs are divided into two categories namely,Vehicle to Vehicle (V2V) and Vehicle to Infrastructure (V2I) [6; 7]. While V2V provides communication between mobile entities, i.e., vehicles moving on the road, V2I supports communication between vehicles and infrastructure, exchanging various types of road environment information. Infrastructure is used as a gateway to the network authority. The communication technologies utilized include Dedicated Short-Range Communication (DSRC), WiMax, Cellular Network, WiFi and the VeMac protocol [8]. DSRC is one of the most widespread technologies used in automotive vehicles and is used as a standard of wireless communication technology in many cars in the market [9]. It is based on the IEEE 802.11p amendment of the IEEE 802.11 standard and operates in the dedicated frequency spectrum of 5.9 GHz. VANETs applications can be divided into two categories, i.e., safety-related applications and comfort applications [1]. The main aim of safety-related applications is the safety of drivers and passengers through the dissemination upcoming hazardous events on the road networks. These applications provide protection by updating the current state of the surrounding environment of the road [10]. It includes road accident information, collision avoidance, lane changing warning, emergency, and so forth. Comfort or non-safety applications provide convenience and comfort to travelers on the road.