  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. Deep 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-scale mobility trace datasets, 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.
