  Public key infrastructure (PKI) is the most widely used security mechanism
for securing communications over the network. However, there are known
performance issues, making it unsuitable for use in vehicular networks. In this
paper, we propose a secure and authenticated key management protocol (SA-KMP)
to overcome the shortcomings of the PKI. The SA-KMP scheme distributes
repository containing the bindings of the en-tity's identity and its
corresponding public key to each vehicle and road side unit. By doing so,
certificate exchanges and certificate revocation lists are eliminated.
Furthermore, the SA-KMP scheme uses symmetric keys derived based on a
3-D-matrix-based key agreement scheme to reduce the high computational costs of
using asymmetric cryptography. We demonstrate the efficiency of the SA-KMP
through performance evaluations in terms of transmission and storage overhead,
network latency, and key generation time. Analytical results show that the
SA-KMP is more scalable and outperforms the certificate-based PKI. Simulation
results indicate that the key generation time of the SA-KMP scheme is less than
that of the existing Elliptic Curve Diffie--Hellman and Diffie--Hellman
protocols. In addition, we use Proverif to prove that the SA-KMP scheme is
secure against an active attacker under the Dolev and Yao model and further
show that the SA-KMP scheme is secure against denial of service, collusion
attacks, and a wide range of other malicious attacks.
