  Significant developments have taken place over the past few years in the area
of vehicular communication (VC) systems. Now, it is well understood in the
community that security and protection of private user information are a
prerequisite for the deployment of the technology. This is so, precisely
because the benefits of VC systems, with the mission to enhance transportation
safety and efficiency, are at stake. Without the integration of strong and
practical security and privacy enhancing mechanisms, VC systems could be
disrupted or disabled, even by relatively unsophisticated attackers. We address
this problem within the SeVeCom project, having developed a security
architecture that provides a comprehensive and practical solution. We present
our results in a set of two papers in this issue. In this first one, we analyze
threats and types of adversaries, we identify security and privacy
requirements, and we present a spectrum of mechanisms to secure VC systems. We
provide a solution that can be quickly adopted and deployed. In the second
paper, we present our progress towards the implementation of our architecture
and results on the performance of the secure VC system, along with a discussion
of upcoming research challenges and our related current results.
