A Review of Security Threats, Solutions and Trust Management in VANETs

The real time implementation of Vehicular Ad-Hoc Network (VANET) applications is challenging unless their security and privacy requirements are strongly addressed. Thus many researchers’ attention is directed towards providing security solutions that mitigate threats to VANET environments. In this paper we give readers an overview of the VANET environment, Intelligent Transport System (ITS) communication configurations and wireless access standards used in VANETs. We have described a general VANET model, the VANET Communication Evaluation Model (VCEM) with two of its communication environments Vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) in the context of security, privacy and trust. The roles and relationships of several participating entities in these communication environments along with a few important communication patterns, critical to VANETs are also discussed. The typical security requirements for VANETs are discussed and the categorization of several security threats to these requirements is made. A description on the relevance of these threats for VANETs with illustrations is also made. We have discussed the general working of two types of security schemes, one based on Public Key Infrastructure (PKI) and the other on ID-based cryptosystems. We have outlined the features of various PKI based security schemes and their drawbacks in general. We have focused on several ID based cryptosystems and briefly outlined their merits and demerits with a comparison on performance. In this paper, we have also discussed an important VANET issue, trust among peers. Various types of trust management models in VANETs and the related research efforts have been summarized. The significant properties of an efficient trust management model are discussed and a comparative study of few of the existing trust management schemes is made. Finally the challenges in developing secured VANET applications are presented.