In the near future, it is expected that vehicles which increasingly become an intelligent systems will be equipped with radio communications interfaces. Thus, vehicular networks can be formed and they are commonly known as VANETs (Vehicular Ad hoc NETworks), a use case of mobile ad hoc networks where cars are the mobile nodes. As VANETs exhibit several unique features such as the high mobility of nodes, short connection times, etc. conventional security mechanisms are not always effective. Consequently, a wide variety of research contributions have been recently presented to cope with the intrinsic characteristics of vehicular communication. This paper provides a summary of the recent state of the art of VANETs, it presents the communication architecture of VANETs and outlines the privacy and security challenges that need to be overcome to make such networks safety usable in practice. It identifies all existing security problems in VANETs and classifies them from a cryptographic point of view. It regroups, studies and compares also the various cryptographic schemes that have been separately suggested for VANETs, evaluates the efficiency of proposed solutions and explores some future trends that will shape the research in cryptographic protocols for intelligent transportation systems. (C) 2014 Elsevier Inc. All rights reserved.
