# EAIA: An Efficient and Anonymous Identity-Authentication Scheme in 5G-V2V
## 1 Introduction  
In recent years, the technology of connected vehicles has been evolving toward greater intelligence and network integration [1]. Vehicle-to-Everything (V2X) technology has become a key enabler for the exchange of information in intelligent connected vehicles. V2X technology enhances vehicles' perception of the traffic environment by enabling early access to information such as the operational data of nearby vehicles, traffic control information, congestion data, and visual blind spots, thereby facilitating information sharing among vehicles. It encompasses four main types: Vehicle-to-Infrastructure (V2I), Vehicle-to-Vehicle (V2V), Vehicle-to-Pedestrian (V2P), and Vehicle-to-Network (V2N) communication [2]. V2I communication focuses on the interaction between vehicles and road infrastructure to receive local traffic broadcasts. V2V communication primarily involves active safety services related to communication with surrounding vehicles, such as forward collision warnings, emergency braking alerts, and lane change warnings. V2P communication deals primarily with pedestrian safety alerts. V2N communication revolves around intelligent control services such as route planning, remote control, and dynamic map downloads. Among these, V2V refers to the communication between vehicles through onboard terminals, playing a crucial role in V2X [3] by ensuring safer and more enjoyable driving experiences through the exchange of information like speed, location, and direction, allowing for real-time prediction and the avoidance of potential collisions, optimizing traffic flow, reducing accidents, and enhancing energy and road use efficiency. With the global commercial rollout of the fifth-generation mobile network (5G), Cellular-V2X (C-V2X) communication assisted by 5G base station gNodeB (gNB) has been recognized as a promising vehicular communication method due to its low latency [4]. In 5G, security requirements mainly include confidentiality, integrity, authenticity, privacy, and availability. Meanwhile, 5G-V2V is becoming increasingly important as V2X communication involves the exchange of sensitive information among vehicles, infrastructure, and other entities, providing ultra-low latency and excellent reliable connectivity under high mobility and density for situational awareness of the surrounding environment. Therefore, securing 5G-V2V is crucial [5]. Authentication and encryption are fundamental components of secure communication protocols in the 5G-V2X domain [6]. Authentication ensures the verification of the identities of communication entities, preventing unauthorized access and message forgery. On the other hand, encryption ensures the confidentiality of transmitted data, preventing unauthorized disclosure. In direct vehicle communication, it is essential to ensure the authenticity of the transmitter's identity to prevent impersonation during message transmission. Mutual authentication is fundamental to ensure that both parties are communicating with legitimate entities and not attempting to impersonate someone else. However, while information sharing among vehicles offers many benefits, it also brings the possibility of various malicious attacks. To address the security and privacy issues in VANETs, various authentication schemes have been proposed, such as those based on symmetric and public key cryptography [7; 8]. In these schemes, a Trust Authority (TA) controls the composition of public and private key pairs and their distribution to legitimate members. Most of these rely on infrastructure like roadside units (RSUs) or TAs for the centralized management of vehicle information. However, such external facilities may not be available in remote/rural areas [9]. This paper proposes an ECC-based lightweight anonymous V2V mutual authentication protocol, EAIA, which can authenticate vehicles locally without the involvement of trusted authorities or other infrastructure.