OTIBAAGKA: A New Security Tool for Cryptographic Mix-Zone Establishment in Vehicular Ad Hoc Networks

Location privacy is one of the major challenges in vehicular ad hoc networks. Due to the open and broadcast nature of wireless communication, the safety messages of vehicles can be easily collected by malicious eavesdroppers to continuously track vehicles. Cryptographic mix-zone (CMIX) is a promising tool to enhance vehicle privacy, in which the safety messages of vehicles are encrypted using a group secret key. In that way, any outsider cannot monitor the safety messages broadcasted by the vehicles in the CMIX. Existing CMIX protocols need fully trusted dealers to distribute group secret keys and/or suffer from the problem of efficient key update. This paper proposes a novel method based on a new security tool referred to as one-time identity-based authenticated asymmetric group key agreement to create CMIXes which withstand malicious eavesdroppers. Different from the existing solutions, our proposal does not rely on the existence of fully trusted dealers and deals with efficient key update in CMIX for the first time. In our protocol, any vehicle in a CMIX could be a group secret key distributer. Furthermore, once the group secret key of the CMIX has to be updated, a vehicle in the CMIX just needs to broadcast a short ciphertext, then all the vehicles in the CMIX may refresh the group secret key to the new one efficiently.