3TAAV: A three-tier architecture for pseudonym-based anonymous authentication in VANETs

Vehicular Ad-hoc Network (VANET) is an emerging communication framework to abet in day-to-day management of vehicular traffic and safety of vehicles. Anonymous authentication is one of the key requirements in VANET ensures the privacy of the origin of the message. Existing security protocols in VANETs, that provide anonymous authentication based on the two-tier architecture, consists of two VANET elements, namely vehicles and road side units (RSUs) working as the key generating server (KGS). These protocols rely heavily on RSU to provide anonymous identity to vehicles. In these protocols, with the movement of the vehicle from one RSU to another RSU, a fresh anonymous identity needs to be generated for every vehicle with additional handing over and taking over procedures. In this paper, we propose a novel security protocol for anonymous authentication based on three-tier architecture involving three VANET elements, viz., vehicle, RSU and pseudonym server (PSS) for achieving multiple levels of anonymity in VANETs. The proposed protocol reduces the overhead incurred by the RSU for certificate management and eliminates the requirement of handing over and taking over of vehicles while changing from one RSU to another. Considering the overhead of RSU in certificate management, the number of pseudonyms cached by each vehicle and blackout-time (duration for which vehicle is not part of VANET due to non-acquisition of pseudo-identity) as performance metrics for simulation, the simulation results demonstrate the efficacy of the proposed approach.