## 2 Background and Related Work
### Related Work
The results demonstrate the protocol's secure and efficient authentication and key exchange for fog-driven IoT healthcare systems. However, there are some limitations to this protocol. The attacker can perform a password guessing attack. Additionally, it is considerably resource expensive. [PERSON] et al. [43] propose a mutual handover authentication in a vehicular network environment. The paper focuses on the challenge of secure fog computing service handover in vehicular networks. It aims to establish mutual authentication between vehicles and fog nodes (FNs) to ensure the integrity and privacy of vehicular network systems. The environment consists of vehicles, fog nodes deployed on roadside units (RSUs), and a cloud server (CS) that facilitates authentication. The scheme utilizes one-way hash functions and exclusive or operations to ensure its lightweight nature. During the login and service request phases, the cloud server distributes credentials for on-the-road authentication between vehicles and fog nodes. During the handover process, the vehicle and fog node can perform mutual authentication using login credentials. The approach achieves computational efficiency by providing faster computation and reducing the total message size compared to previous authentication schemes in similar environments. This scheme's validation using the SPAN software based on AVISPA confirms its effectiveness in achieving mutual authentication goals and its resilience against replay and man-in-the-middle attacks. However, this paper does not discuss how CS distributes user credentials to specific fog nodes. Ref. [44] introduces a novel anonymous handover authentication scheme for fog computing. The paper addresses the problem of secure handover authentication for mobile devices in fog computing environments. Handovers, where mobile devices transition between different fog access points, require authentication mechanisms that ensure secure communication while maintaining efficiency and preserving user privacy. In this protocol, edge users and fog nodes have to register in a registration authority (RA), then retrieve their unique identity and compute the corresponding pseudo-identity. After edge users log in and authenticate with one fog node, they move to another fog node, and the pre-negotiation between the old and new fog nodes happens. Then, the edge user can authenticate with a new fog node. The encryption methods used in this protocol are all lightweight, such as concatenation and bitwise XOR operation. The proposed FogHA scheme leverages symmetric trivariate polynomials to provide low-latency authentication while ensuring security, user anonymity, and resistance against known attacks. The authors analyze the security of FogHA using the real-or-random (ROR) model. The analysis demonstrates the semantic security of the scheme, indicating its resilience against potential attacks. An informal security analysis displays FogHA's ability to resist various known attacks, including mutual authentication, replay attacks, man-in-the-middle attacks, and impersonation attacks. [PERSON] et al. [45] proposed a threshold mutual authentication protocol that supports fast handover. The work focuses on the problem of secure and efficient access authentication in vehicular networks. Existing authentication protocols often lack consideration for attacks like single points of failure and fail to reduce authentication delays. The authors aim to tackle these challenges and provide a decentralized authentication architecture that enhances security and efficiency. The paper assumes a vehicular network environment comprising a registration server (RS), edge nodes (ENs) such as roadside units (RSUs) and base stations (BSs), and vehicles. The RS is considered a trusted party responsible for registration and revocation. Vehicles are assumed to be potentially malicious, while attackers could compromise ENs. The communication channel between vehiclesand ENs is vulnerable to various attacks.