A cooperative message authentication protocol in VANETs

Safety provision is a crucial application for the vehicular ad hoc networks (VANETs). In the VANETs, vehicles periodically broadcast their geographic information. Therefore, collisions can be avoided. In this paper, we address the issue of large computation overhead caused by the safety message authentication. A cooperative message authentication protocol(CMAP) is presented to alleviate vehicles´ computation burden. In the protocol, because vehicles share their verification results with each other in a cooperative way, the number of safety messages that each vehicle needs to verify will be reduced greatly. A new research issue of the protocol is how to select verifiers in the city road scenario. Thus, we propose three verifiers selection algorithms, n-nearest method, most-even distributed method and the compound method for the CMAP. Based on the simulation results from NS2, comparisons between these three methods and the existing work are given at the end of the paper to demonstrate the performance of our protocol.