Mitigating Sybil Attacks in V2X Communication Through Cryptographic Trust Anchors

Abstract

Vehicle-to-Everything (V2X) communication enables vehicles to exchange safety-critical messages, but its reliance on temporary pseudonymous identities makes it vulnerable to Sybil attacks, where a single attacker fabricates multiple identities to inject false information into the network. This paper presents a lightweight cryptographic mechanism that combines SHA-256 Proof-of-Work token mining with a time-windowed ratecontrol layer to limit the number of new identities a vehicle can activate within a given interval. The mechanism was implemented in Java and evaluated through a parametric simulation across three independent variables: PoW difficulty, rate limit, and attack intensity. Results show that a difficulty of 4 and a rate limit of 5 tokens per 10-second window provide an effective balance between Sybil resistance and legitimate vehicle access in an 8-vehicle scenario, with an average mining time of 0.227 seconds. The evaluation identifies the rate-control layer as the primary security mechanism, while PoW difficulty increases the computational cost per identity without independently capping accepted tokens. The proposed approach is infrastructure-free and suitable for regulated V2X deployments where attackers represent a minority of the network.