Vehicular Communications (VC) are reaching a near deploment phase and will play an important role in improving road safety, driving efficiency and comfort. The industry and the academia have reached a consensus for the need of a Public Key Infrastructure (PKI), in order to achieve security, identity management, vehicle authentication, as well as preserve vehicle privacy. Moreover, a gamut of proprietary and safety applications, such as location-based services and pay-as-you-drive systems, are going to be offered to the vehicles. The emerging applications are posing new challenges for the existing Vehicular Public Key Infrastructure (VPKI) architectures to support Authentication, Authorization and Accountability (AAA), without exposing vehicle privacy. In this work we present an implementation of a VPKI that is compatible with the VC standards. We propose the use of tickets as cryptographic tokens to provide AAA and also preserve vehicle privacy against adversaries and the VPKI. Finally, we present the efficiency results of our implementation to prove its applicability.

- Several years of academic and industrial research efforts have converged to a common understanding on fundamental security building blocks for the upcoming Vehicular Communication (VC) systems. There is a growing consensus towards deploying a Vehicular Public-Key Infrastructure (VPKI) enables pseudonymous authentication, with standardization efforts in that direction. However, there are still significant technical issues that remain unresolved. Existing proposals for instantiating the VPKI either need additional detailed specifications or enhanced security and privacy features. Equally important, there is limited experimental work that establishes the VPKI efficiency and scalability. In this paper, we are concerned with exactly these issues. We leverage the common VPKI approach and contribute an enhanced system with precisely defined, novel features that improve its resilience and the user privacy protection. In particular, we depart from the common assumption that the VPKI entities are fully trusted and we improve user privacy in the face of an honest-but-curious security infrastructure. Moreover, we fully implement our VPKI, in a standard-compliant manner, and we perform an extensive evaluation. Along with stronger protection and richer functionality, our system achieves very significant performance improvement over prior systems - contributing the most advanced VPKI towards deployment.

Vehicular Communication (VC) systems will greatly enhance intelligent transportation systems. But their security and the protection of their users’ privacy are a prerequisite for deployment. Efforts in industry and academia brought forth a multitude of diverse proposals. These have now converged to a common view, notably on the design of a security infrastructure, a Vehicular Public Key Infrastructure (VPKI) that shall enable secure conditionally anonymous VC. Standardization efforts and industry readiness to adopt this approach hint to its maturity. However, there are several open questions remaining, and it is paramount to have conclusive answers before deployment. In this article, we distill and critically survey the state of the art for identity and credential management in VC systems, and we sketch a roadmap for addressing a set of critical remaining security and privacy challenges.

Standardization and harmonization efforts have reached a consensus towards using a special-purpose Vehicular Public-Key Infrastructure (VPKI) in upcoming Vehicular Communication (VC) systems. However, there are still several technical challenges with no conclusive answers; one such an important yet open challenge is the acquisition of shortterm credentials, pseudonym: how should each vehicle interact with the VPKI, e.g., how frequently and for how long? Should each vehicle itself determine the pseudonym lifetime? Answering these questions is far from trivial. Each choice can affect both the user privacy and the system performance and possibly, as a result, its security. In this paper, we make a novel systematic effort to address this multifaceted question. We craft three generally applicable policies and experimentally evaluate the VPKI system performance, leveraging two large-scale mobility datasets. We consider the most promising, in terms of efficiency, pseudonym acquisition policies; we find that within this class of policies, the most promising policy in terms of privacy protection can be supported with moderate overhead. Moreover, in all cases, this work is the first to provide tangible evidence that the state-of-the-art VPKI can serve sizable areas or domain with modest computing resources.

Several years of academic and industrial research efforts have converged to a common understanding on fundamental security building blocks for the upcoming Vehicular Communication (VC) systems. There is a growing consensus towards deploying a special-purpose identity and credential management infrastructure, i.e., a Vehicular Public-Key Infrastructure (VPKI), enabling pseudonymous authentication, with standardization efforts towards that direction. In spite of the progress made by standardization bodies (IEEE 1609.2 and ETSI) and harmonization efforts (Car2Car Communication Consortium (C2C-CC)), significant questions remain unanswered towards deploying a VPKI. The precise understanding of the VPKI, a central building block of secure and privacy-preserving VC systems, is still lacking. This paper contributes to the closing of this gap. We present SECMACE, a VPKI system, which is compatible with the IEEE 1609.2 and ETSI standards specifications. We provide a detailed description of our state-of-the-art VPKI that improves upon existing proposals in terms of security and privacy protection, and efficiency. SECMACE facilitates multi-domain operations in the VC systems and enhances user privacy, notably preventing linking pseudonyms based on timing information and offering increased protection even against honest-but-curious VPKI entities. We propose multiple policies for the vehicle-VPKI interactions based on which and two large mobility traces, we evaluate the full-blown implementation of SECMACE. With very little attention on the VPKI performance thus far, our results reveal that modest computing resources can support a large area of vehicles with very low delays and the most promising policy in terms of privacy protection can be supported with moderate overhead.