# Virtual Pseudonym-Changing and Dynamic Grouping Policy for Privacy Preservation in VANETs
###### Abstract
This includes weather information, location services, nearest restaurant, games, advertisements, and so on. The Basic Safety Message (BSM) or Cooperative Aware Message (CAM), are beacon messages that are broadcast through the road environment to inform other nodes in the network about the road status information. The message contains the vehicle identity, speed, direction, location, and other information. This information is disseminated in the network in an open form, and everyone can access it, even if they are adversary or attacker. If an adversary catches the actual identity of a vehicle during a trip, they may come to know various locations visited by the vehicle driver. In this way, the adversary comes to know the behavior of the vehicle driver, producing various types of threats that may be physical harassment, damage to social reputation, property loss, and blackmail [11]. To protect location privacy in the case of VANETs, a pseudonym may be used in the beacon message instead of the actual identity of a vehicle. A pseudonym is a temporary identifier often used for a short period of time. However, the use of fixed pseudonyms don't solve the privacy problem of a vehicle driver. Pseudonyms should be changed periodically to confuse an adversary about the actual vehicle communicating during a road network journey. To solve the problem of location privacy in existing literature, various pseudonym-changing schemes have been proposed that are based on the concept of a mix zone concept [12; 13; 14; 15] and a silent period [16; 17; 18]. In the mix zone method, vehicles' identities are mixed in specific areas that may be a fixed zone at a road intersection or some congested area of vehicles. These schemes can achieve a high level of location privacy in high vehicle traffic and at selected places. Still, they have certain limitations that make it difficult to provide privacy in lower-traffic conditions. The vehicles remain silent by not broadcasting beacons messages in silent period-based schemes. This hides the identities of a vehicle for a certain amount of time. These techniques have specific limitations; for example, the achievement of privacy at the cost of compromising road safety application of the vehicular network. There are some situations in which it is difficult for a vehicle to become silent in a cooperative manner; ultimately, the vehicle should remain silent in an independent manner, which reduces privacy protection. The schemes mentioned above are challenging to apply in the case of higher speed travel and low traffic density. Thereremains a need for a scheme that provides location privacy on a highway or main roads where vehicles are moving at high speed. To solve the problems mentioned in the existing literature, we propose a new scheme of distributed and dynamic virtual grouping that protects location privacy on main roads of the vehicular network. The context-aware scheme CLPS, ref. [18] requires a vehicle to be synchronized with silent neighbors to change pseudonyms during a silent period for identity protection. However, the using isolated roads and short silent periods can assist an adversary in detecting the target vehicle. Moreover, once a subject vehicle has knowledge of neighbor's pseudonyms, which provides a way for a linkability of pseudonyms. In [10], privacy is also preserved only while the vehicle is in the communication range of RSU. In this paper, we propose a Dynamic Grouping and Virtual Pseudonym (DGVP) exchange scheme that provides location privacy to the vehicle in the road network. Our contributions in this paper are given below. * We introduce the concept of distributed and dynamic grouping based on road context information. Vehicles with similar status are combined in a group whose size depends on the number of transmission range neighbors; the pseudonyms are changed cooperatively. * The proposed scheme improves location privacy in low vehicle traffic density environments.