# A Secure and Efficient Authentication Scheme for Fog-Based Vehicular Ad Hoc Networks
###### Abstract  
Recently, the application of fog-computing technology to vehicular ad hoc networks (VANETs) has rapidly advanced. Despite these advancements, challenges remain in ensuring efficient communication and security. Specifically, there are issues such as the high communication and computation load of authentications and insecure communication over public channels between fog nodes and vehicles. To address these problems, a lightweight and secure authenticated key agreement protocol for confidential communication is proposed. However, we found that the protocol does not offer perfect forward secrecy and is vulnerable to several attacks, such as privileged insider, ephemeral secret leakage, and stolen smart card attacks. Furthermore, their protocol excessively uses elliptic curve cryptography (ECC), resulting in delays in VANET environments where authentication occurs frequently. Therefore, this paper proposes a novel authentication protocol that outperforms other related protocols regarding security and performance. The proposed protocol reduced the usage frequency of ECC primarily using hash and exclusive OR operations. We analyzed the proposed protocol using informal and formal methods, including the real-or-random (RoR) model, Burrows-Abadi-Nikogadam (BAN) logic, and automated validation of internet security protocols and applications (AVISPA) simulation to show that the proposed protocol is correct and secure against various attacks. Moreover, We compared the computational cost, communication cost, and security features of the proposed protocol with other related protocols and show that the proposed methods have better performance and security than other schemes. As a result, the proposed scheme is more secure and efficient for fog-based VANETs.  
fog computing; vehicular ad hoc network; lightweight; key agreement; perfect forward secrecy; BAN logic; RoR model; AVISPA simulation 2020 IEEEexample: accepted: 15 202  
vehicle; thus, processing the numerous data generated by a vehicle results in high latency and communication costs.  
Fog computing [4] is a promising solution to improve the functionality of VANET environments, providing real-time processing and storage capabilities and using the communication and computing resources of each vehicle more efficiently. Furthermore, fog computing enables efficient data processing, enhanced scalability, and low-latency communication by extending the concept of cloud computing to the network edge in VANET environments [5]. Therefore, integrating fog computing with VANETs is necessary to improve the capabilities of autonomous vehicles.  
However, fog-based VANETs encounter security challenges that threaten road safety and system integrity [6]. The interconnectedness of vehicles makes them vulnerable to cyberattacks, and messages transmitted over VANETs on public channels can be hampered with, replayed, intercepted, or deleted by an attacker. Moreover, the dynamic characteristics of fog nodes and reliance on wireless communication necessitate a robust authentication scheme to safeguard operations in fog-based VANETs [7]. Fog-based VANETs must satisfy certain security requirements, such as secure data transmission, privacy protection, and authentication.  
Therefore, robust security protocols must be developed to authenticate entities and reduce potential threats. In 2024, [PERSON] et al. [8] proposed a secure and lightweight authentication scheme to strengthen the security of fog-based VANETs. However, problems typically occur, such as session key exposure due to ephemeral secret leakage attacks and high communication costs due to the frequent use of public keys. Therefore, this paper proposes an improved protocol to address these security concerns effectively and enhance the overall reliability and efficiency of fog-based VANETs.