Analysis of Group Key Management Protocols for Secure Multicasting in Vehicular Software Distribution Network

In this paper we investigate the issues in designing key management architecture for secure multicasting in remote software distribution to advance vehicles. We consider the vehicular software distribution network (VSDN) as wireless network where vehicles are connected to the software distributors through roadside base stations (BSs). The large VSDN is divided into small regions and a Regional Group Manager (RGM) manages a region. Depending on the level of trust in the supporting BSs, we propose two group key management (GKM) protocols for the multicast groups (MGs) formed for software distribution. We categorize the VSDN as fully- trusted and semi-trusted systems. In a fully-trusted system the BSs have access to the multicast data and take part in GKM whereas in a semi-trusted system the BSs are not allowed to understand the multicast data, rather they act as proxies for the vehicles by honestly relaying the encrypted multicast data from the RGM to the vehicles. We compare the performance of these two protocols in terms of computation and communication overhead incurred on each entity involved during multicast session initialization, re-keying and handoff, storage overhead, security and scalability. Our analysis shows that the GKM protocol efficiency can be traded-off with the level of trust on the BSs.