Real-world evaluation of an anonymous authenticated key agreement protocol for vehicular ad-hoc networks

Vehicles in Vehicular Ad-Hoc NETworks (VANETs) use applications which require an exchange of application-specific confidential data between vehicles. This data must be protected from vehicles not using the application. To achieve this, the vehicles have to authenticate each other in a way that the other communication partner is convinced that the vehicle is eligible to exchange the data. Furthermore, both partners have to agree on an encryption key. This kind of protocols is known as approaches to authenticated key agreement. The proprietary protocol implemented and evaluated in this paper supports these properties and, in addition, preserves the privacy of the vehicles. After executing the protocol, neither one of the participating vehicles nor an eavesdropping third vehicle in communication range can unveil the identity of the vehicles. This important property is achieved by combining the Elliptic Curve Integrated Encryption Scheme (ECIES) with ring signatures. Furthermore, we demonstrate how this protocol can be applied within a GeoNetworking message. We present a prototype of the protocol and discuss evaluation results produced from a test setup with real vehicles. The results show that a feasible ring size can be established to reliably protect the privacy of the vehicles. We also analyse the execution time of the complete protocol, of the constituent protocol steps as well as of the different components like security and transmission. The presented results clearly show that the protocol can be completed on time, even when the communicating vehicles have a high relative velocity and poor communication range.