## 1 Introduction  
The vehicular Ad-Hoc Network (VANETs) is the future generation technique for intelligent transportation system (ITS). In general, VANETs is the subdivision of the mobile Ad-Hoc Networks (MANETs) that gain more attention from the government, academic and industrial sector [1]. The main types of VANETs communicate vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I). Commonly, the VANET network is equipped with a trusted authority (TA) and Road-Side Units (RSUs) to control the vehicles in the network. Each vehicle consists of a tamper-proof device called the On-Board Unit (OBU), which is mainly used to accumulate significant secret vehicle information and vehicle identity. Earlier, in a maximum of cases, vehicle-to-vehicle communication took place, but in recent days, information has been transmitted from vehicles to the nearby RSUs [2]. The significant challenges in VANETs are it needs low latency, high safety, speed, and stability [3]. Additionally, through an improper mobility model the energy consumption, latency and overhead are increased in the real traffic scenario [4]. VANETs are highly susceptible to malicious behaviors such as eavesdropping, impersonation, etc. To protect the network from such malfunctions, several authentications as well as cryptography techniques are developed, but it has certain drawbacks when applied to huge dynamic mobility-based VANETs. In classic authorization and revocation schemes, digital signature and cryptography technologies overhead occur when it is applied to high-speed VANETs. The trustworthiness and messages are moderate. In a dynamic vehicular network, the road environment is complex, so achieving high stability is an essential task. Figure 1 shows the communication types in VANETs. Many concepts are introduced by the researchers to solve the privacy issues in VANETs in order to fulfill the indispensable prerequisite such as reliability, traceability, and link stability, etc., but those methods produce high communicational overhead during the process of communication in the network, and it requires substantial memory space [5; 6; 7]. In recent studies, pseudonym-based message authentication, as well as group-based message authentication, are initiated, which helps to improve the privacy of the trusted authority (TA) in VANETs [8; 9]. Meticulously, privacy-preserving features must be guaranteed in VANETs. The process of authentication during communication secures the real identities of vehicles from attackers. Racing those vehicles, the TA needs an efficient method to find the real identities of vehicles, due to this criteria's creating high-speed VANETs with efficient real-time authentication, which is still an open research area [10]. In VANETs, communication takes place in open wireless communication. Vehicle-to-vehicle and vehicle-to-infrastructure communications are conducted through open wireless channels so that the attacker vehicle can, without difficulty, alter the process by interrupting and deleting the information. The attacker vehicle can easily arrest the real identities and other traffic-oriented details of the vehicles, which are very dangerous for the drivers. In some cases, the attacker vehicle broadcasts a false message that leads to traffic problems such as congestion and road accidents. For this reason, researchers provide more attention to VANETs security [11; 12]. It is essential to design VANETs with well-organized security solutions. The efficiency of the VANETs is not only dependent on security; it is also related to the computational cost and communication overhead. The VANETs with high security and less computational overhead lead to efficient vehicular communication, so this research improves the security and reduces the computational cost of the VANETs. The contribution of the research study is given below. The contribution of this research is as follows:  
* Enhancing the performance of high-speed VANETs in terms of security and computational overhead is concentrated.