# Security Challenges of Location Privacy in VANETs and State-of-the-Art Solutions: A Survey
## 3 Related Work
### Location Privacy Preserving Schemes
#### 3.2.1 Group-Based Authentication  
In the group authentication scheme, vehicles are distributed into smaller groups and a group leader is allocated to each group as stated in [41] proposed the Trust-text End of Authentication Mechanism (TEAM), an authentication scheme that allows participants to be co-located. Every participant authenticates to the chief, who then authenticates to the TA via the RSU. At intersections, group leaders may change. A new group is formed after taking turns [42]. The group leader may be a bus, a regular taxi service or a licensed public transport vehicle such as a well-known police patrol vehicle. When a single vehicle goes down or out of the party, you can switch between groups just like your cell phone moves between base stations. Nonetheless, the driver keeps the ID of the vehicle on his own and does not show it to the RSU or the TA. A recent study [43] demonstrates a new method recognized as Trustworthy VANETs Routing with Group Authentication Key (TROPHY) that uses symmetric and asymmetric encryption for authentication inside group members and TAs. This method takes advantage of all regular group-based authentication features with slightly different leader assignments.  
Reference [32] proposed a group-oriented privacy security approach oriented on a post-quantum safe forget transfer protocol, built based on an effective NTRU cryptosystem. Similarly, group-led trust and authentication schemes were also discussed in several other studies [44], each with different methods in addition to maintaining the required location services. Offers the place of anonymity contrasts and critically analyzes the privacy strategies mentioned in this white paper. Advantages of each approach in terms of different operational and safety parameters, For example, ease of implementation, low and heavy performance under highway traffic conditions, personal-specific customized quality, location-based services and a summary of disadvantages. This scheme considers group-based authentication critically and is appropriate for traffic patterns that are similar in. In other words, a group where vehicles are often reconfigured to move in and out of the group can place a computational load on the leader of the OBU. At the other hand, if a malicious individual is part of a specific group, the privacy of each group member may be violated for a certain period.  
Group-based authentication systems have many advantages and disadvantages when growing location-based security services to protect user privacy. Best of all, it is fairly easy to execute this system [45]. The computational load used by the community leader is heavier than the regular OBU, but this aspect can be overcome by assigning leadership to daily vehicles with better computing capabilities. This scheme is supposed to work equally well when considered for low and high traffic. However, if the consumer remains in a specific community for a longer period of time (e.g., on a highway) and the members of the group stay the same, then you can track the vehicle easily. As a result, the performance of highway traffic is considered weak. In addition, TA cannot provide personalized service to the car because it does not have access to the true identity of the car.