# CAVVPM: Challenge-Based Authentication and Verification of Vehicle Platooning at Motorway
###### Abstract  
As a result of vehicle platooning, advantages including decreased traffic congestion and improved fuel economy are expected. Vehicles in a platoon move in a single line, closely spaced, and at a constant speed. Vehicle-to-vehicle communications and sensor data help keep the platoon formation in place, and the CACC system is responsible for maintaining it. In reality, V2V transmissions are essential for reducing platooning distances while still ensuring their safety and security. It is far more difficult to confirm the veracity of a V2V message's content than it is to verify its integrity and source authentication. Only platoon members can send and receive V2V communications by implementing a practical access control mechanism. The goal is to link a prospective platoon member's digital identification to their actual location inside the unit. A physical challenge-response interaction is used in the CAVVPM process to verify that a prospective platoon member respects the rules. The applicant is asked to perform a series of random longitudinal movements, thus, the protocol's name. Remote attackers cannot join the platoon or send bogus C  
(PKI) is recommended by wireless standards such as IEEE 1609.2 [12] and 3 GPP TS 33.185 for cellular vehicle-to-everything (C-V2X) [13] (PKI). A V2V message's authenticity and integrity may be verified using cryptographic techniques. The message originator cannot be tied to a specific path. Remote assaults are possible due to the absence of physical trajectory verification. It is possible even if an opponent claims to be following a platoon from a distance. Communicating with the platoon via C-V2X over the cellular infrastructure is possible. As a legitimate vehicle or a compromised vehicle, the adversary has access to valid cryptographic credentials. Fake communications may be injected into the battalion and disrupt CACC operations once the enemy has authenticated their digital identity. Because the attacker may pose as phantom vehicles in numerous remote areas simultaneously, this assault can be carried out by multiple platoons. Previous publications have offered physical access control systems to reduce the dangers of remote assaults [14; 15; 16; 17]. Only vehicles that confirm they genuinely follow the platoon should have access to the unit. Proof-of-following (PoF), introduced by [PERSON] et al., was used to formalize the idea in Figure 1. Candidate member C participates in a challenge-response process with a verifier V (usually the platoon's last vehicle) to link his online signature with his physical trajectory before being accepted into the platoon. A PoF is a complementary approach to digital authentication since it provides physical access control [18; 19; 20; 21]. Since cars currently in the platoon may send bogus messages, this does not prohibit them from doing so. **Drawbacks of previous approaches**  
The convoy methodology [5] correlates the candidate's and verifier's trajectories using the vertical acceleration caused by differences in the road surface. However, the static road surface makes the convoy susceptible to pre-recorded assaults. The candidate-verifier trajectories may be correlated using the large-scale fading effect of ambient cellular broadcasts, as described in [22]. To prevent pre-recording assaults, this setting has a high spatial and temporal entropy level. Despite this, the protocol cannot determine the exact distance between the applicant and the verifier; instead, it simply limits the candidate to a specific range around the verifier. Consequently, the candidate might be located within a certain radius of the specified location. CAVVPM is a novel proof-of-concept protocol that can verify the distance between vehicles of the candidate, the relative placement of the verifier and the candidate, and the candidate's lane, while also providing resistance to pre-recording assaults. Verification of platoon loyalty is made easy by CAVVPM, which uses a physical challenge-response interaction between candidates and verifiers.