Analysis of Certificate Revocation List Distribution Protocols for Vehicular Networks

PKI-based security in Vehicular Networks has to heavily rely on revoking the malicious user by adding his certificates to a Certificate Revocation List and broadcasting it to all the nodes. In a vehicular network with minimal infrastructure there is a need for a quick and reliable delivery or this CRL to all the nodes. While vehicle-to-vehicle or infrastructure-to-vehicle flooding could seem a natural way to deliver the CRL to all the nodes, existing flooding techniques either are unreliable, generate overwhelming unnecessary retransmission or incur excessive network control overhead. In this paper we study the problem of efficient distribution of CRLs in a vehicular network with minimal infrastructure by analyzing the performance of several broadcast protocols for CRL distribution. Our overall result is the definition and analysis of efficient CRL geo-cast protocols over vehicular networks with realistic scenarios of maps with varying density regions. Previous results did not consider the case of varying density regions or required a significant number of infrastructure servers. In the process, we reduce the problem of efficient geo-cast over a practical geographic map to the much more tractable problem of efficient broadcast over a region with an arbitrary vehicle density, which is solved via natural variants of known broadcasting protocols.