A Scalable Privacy-preserving Authentication Protocol for Secure Vehicular Communications

In this paper, we provide the first scalable privacy-preserving authentication protocol for VANETs without participation of the nearby RSU. Existing authentication methods for VANETs require the participation of the nearby RSUs. So, bottleneck problem can be occurred as increasing the number of vehicles. Also, the time delay to authenticate the nearby vehicle will increase. In order to minimize the participation of the nearby RSU, we propose a verification of the authenticated vehicle, which only requires two modular exponentiations. Our verification methods uses homomorphic encryption algorithm and keyword searching on encrypted data algorithm as cryptographic tools. Through this verification, the vehicle i can verify whether the nearby vehicle j is authenticated by the nearby RSU. As a result, our solution overcomes the inefficiency and bottleneck problem of previous approaches. Our construction of privacy-preserving authentication for VANETs provides better transmission delay between nearby RSU and vehicle.