Infrastructure based Authentication in VANETs

In a vehicular ad-hoc networks (VANETs), the veracity of a message requires authentication of the source vehicle. In this work, a technique for mutual authentication of a vehicle and road side unit (RSU) that preserves the privacy of the vehicle is proposed. The technique relies on the traffic authorities and assumes a hierarchical structure comprising a central trusted authority (TA) with state level trusted authorities (STA) and city level trusted authorities (CTA). Vehicles and RSU have public - private key pairs and each vehicle- CTA and RSU – CTA share a symmetric key. An RSU can be malicious and a vehicle can be malicious and a vehicle can communicate with a CTA only via an RSU and vice-versa. This requires message exchange in the RSU mediated communication between vehicles and CTAs to be confidential. The process is bandwidth efficient and needs only one request-reply message pair between vehicle and the (RSU- CTA-STA-TA) infrastructure. The time taken is in the order of milliseconds which constitutes only a small portion of the stay time of a vehicle within an RSU region.