Performance Analysis of an OCSP-Based Authentication Protocol for VANETs

Abstract

Vehicular Ad-Hoc NETworks (VANETs) improve road safety by preventing and reducing traffic accidents, but VANETs also raise important security and privacy issues. A common approach widely adopted in VANETs is the use of Public Key Infrastructures (PKI) and digital certificates in order to enable authentication and confidentiality, usually relying on a large set of regional Certification Authorities (CAs). Despite the advantages of the latter approach, it raises new problems related with the secure interoperability among the different –and usually unknown- issuing CAs. This paper addresses authentication and interoperability issues in vehicular communications, considering an interregional scenario where mutual authentication between all the nodes is needed. The use of an Authentication Service (AS) is proposed, which supplies vehicles with a trusted set of authentication credentials by implementing a near real-time certificate status service via the well-known Online Certificate Status Protocol (OCSP). The proposed AS also implements a mechanism to quantitatively evaluate the trust level of a CA, in order to decide on-the-fly if an interoperability relationship can be created. The feasibility and performance of the proposed mechanisms are demonstrated via simulations and quantitative analyses by providing a set of communication measurements considering an urban scenario.