# A Low-Overhead Message Authentication and Secure Message Dissemination Scheme for VANETs
###### Abstract  
Given the enormous interest shown by customers as well as industry in autonomous vehicles, the concept of Internet of Vehicles (IoV) has evolved from Vehicular Ad hoc NETworks (VANETs). VANETs are likely to play an important role in Intelligent Transportation Systems (ITS). VANETs based on fixed infrastructures, called Road Side Units (_RSUs_), have been extensively studied. Efficient, authenticated message dissemination in VANETs is important for the timely delivery of authentic messages to vehicles in appropriate regions in the VANET. Many of the approaches proposed in the literature use _RSUs_ to collect events (such as accidents, weather conditions, etc.) observed by vehicles in its region, authenticate them, and disseminate them to vehicles in appropriate regions. However, as the number of messages received by _RSUs_ increases in the network, the computation and communication overhead for _RSUs_ related to message authentication and dissemination also increases. We address this issue and propose a low-overhead message authentication and dissemination scheme in this paper. We compare the overhead, related to authentication and message dissemination, of our approach with an existing approach and also present an analysis of privacy and security implications of our approach. VANET; security and privacy; internet of vehicles; internet of things; intelligent transportation systems +
Footnote †: journal: Network  
The authors in [5] proposed an accident prediction system for VANET. The crash risk in their system can be observed using velocity, driver fatigue, weather conditions, vehicles density, and crash location. They used a hidden Markov model to model the correlation between these observations and the crash risk. The results of their proposed system show the ability to detect potential crashes [5]. Over the past few years, researchers in both academia and industry have continuously worked on designing efficient schemes for privacy-preserving authentication and secure message dissemination in VANETs. Clustering techniques have been used in V2V communication-based VANET architectures, wherein the network is divided into multiple clusters and one node in each cluster is selected as their Cluster Head (\(CH\)). The \(CH\) is responsible for all local cluster communication. This clustering technique helps with reducing the message overhead because it restricts the communication between \(CH\) and the members in its cluster. The \(CH\) can collect and also process and aggregate information from its cluster members and then propagate them to other clusters through other \(CH\)s [6; 7]. Many researches proposed schemes [8; 9] for electing \(CH\)s in each cluster based on specific parameters, such as vehicle location, vehicle speed, etc. Dividing the network into multiple clusters reduces the communication overhead and improves the network efficiency. In infrastructure-based architectures for VANETs, vehicles use Road Side Units (\(RSU\)s) to form a VANET. In some schemes [10; 11], vehicles authenticate each other, while in other schemes [12; 13], vehicles use \(RSU\)s for authenticating disseminating messages sent by vehicles in its region. If traffic becomes heavy, it may not be possible for \(RSU\)s to receive messages about events observed by all vehicles in its region, authenticate them, and disseminate them in a timely manner, especially because the same event will be observed and sent by many vehicles in its region. In this paper, we address this problem and propose a solution. In our approach, when the density of vehicles in an \(RSU\)'s region is high, the \(RSU\) divides its region within its transmission range into several sub-regions and selects one vehicle in each sub-region as the Group Leader (\(GL\)). The \(GL\) selected in a sub-region is supposed to collect messages sent by vehicles in its sub-region, authenticate them, aggregate them, and forward them to the \(RSU\). This reduces the overhead related to message authentication for the \(RSU\).