Design And Security Analysis Of Anonymous Authentication Protocol In VANETs

As an important foundation of intelligent transportation system, Vehicular Ad Hoc Networks (VANETs) have attracted the high attention of academia, automobile manufacturing industry and governments. Vehicles equipped with Onboard Unit (OBU) and Roadside Unit (RSU) form a large-scale network with multi-hop communication by self-organizing network technology. VANETs are intended to improve the comfort of drivers and passengers, enhance road safety and improve traffic efficiency through information exchange, which will bring a revolutionary development to traffic safety management.The communication in VANETs is vulnerable to various types of security attacks because it is constructed based on open and insecure wireless communication. The authentication protocols are introduced into VANETs to ensure the security of messages. However, the special network characters of VANETs bring three key issues to authentication protocols. (1) Security:Authentication protocols should resist all kinds of network security attacks and ensure the integrity and authenticity of messages. (2) Efficiency:The efficiency of authentication protocols should achieve higher levels of requirement due to the instantaneity of the vehicular communication, the strong timeliness of the message, and the large-scale size of the VANETs. (3) Privacy protection:The special characters of VANETs, such as self-organization and open and large scale, make VANETs is vulnerable to privacy disclosure. Therefore, the protocols should provide privacy protection; in some scenarios, anonymous communication is likely abused by malicious attackers, so authentication protocols should be able to trace the real identities of anonymous messages under certain conditions, i.e. the protocols should provide condition privacy-preserving. Research on authentication protocols for VANETs has become a hotspot, and more and more researchers begin to study this hotspot and have put forward many interesting research works. But the existing works are unable to address the three key issues concurrently, and cannot meet the security requirements of VANETs.This dissertation analyzes the application requirements of VANETs, and studies the system model and network characters, then designs new authentication protocols for VANETs. The main contributions of this dissertation are the following four aspects.(1) Security application is one of the most important applications in VANETs. Vehicles running on roads receive a lot of security-related messages in a short time. These messages should be processed immediately, or it may do harm to traffic, and even makes cause body injuries. How can vehicles with limited computing power process messages rapidly and efficiently is the key to implement security application successfully. However, the existing authentication protocols using bilinear pairing for VANETs are inefficient and cannot meet the requirements. To solve this problem, this dissert propose a new anonymous authentication protocol by using bilinear pairing. The protocol provides an efficient message signing and verifying algorithm, and provides the function of batch verification, random anonymous signature and conditional privacy-preserving. The security proof proves the security of the protocol. The performance analysis shows that the protocol decreases computation cost in message signing and verifying phase when compared with most recent proposed similar protocols.(2) The existing message authentication protocols for VANETs mainly construct signing and verifying algorithms by using bilinear pairing. However, the bilinear pairing operation is one of complex operations in modern cryptography, so the efficiency of message authentication performed by vehicles with limited computing capability cannot meet the requirement of VANETs. In addition, the overmuch communication cost added by the signature can hardly meet the communication requirement. To meet the strict requirement of authentication and communication cost simultaneously in VANETs, this dissertation proposes a lightweight anonymous authentication protocol without bilinear pairing for VANETs. The protocol decreases the complexity of cryptographic operations on signature by using non-singular elliptic curve cryptosystem (ECC). The protocol provides an efficient authentication way and conditional privacy-preserving without using any bilinear pairing operations. Security analysis demonstrates that the protocol satisfies all security and privacy requirements for VANETs. Performance analysis shows that the protocol sharply decreases the computation cost and communication cost when compared with the most recent proposed protocols using bilinear pairing.(3) The application to improve traffic efficiency is one of the most important applications of VANETs. This kind of application requires a large amount of large-scale and real-time data. Vehicles collect and forward their sensory traffic data to the application servers through multi-hop communication. In the process of message forwarding, the intermediate node, such as vehicles or RSU, should verify and aggregate the received messages before forwarding them to the servers. The verification efficiency and communication cost are very important to the application. To decrease communication cost further, this dissertation proposes an anonymous authentication protocol based on signature aggregation. The protocol can achieve signature aggregation and authentication while protect users’ privacy. The security proof proves the security of this protocol. The performance analysis shows the protocol has better performance than similar protocols, such as it incurs less computation and communication cost during message signing phase and verification phase, it further decreases communication cost during signature aggregation phase.(4) Traditional single-server registration mechanism is no longer suitable for multi-server architecture of Vehicular Cloud Computing (VCC). The existing authentication protocols for multi-server architecture use the complex bilinear pairing operations, which cannot meet the strict requirements of VANETs on authentication and communication costs. This dissertation proposes a new efficient anonymous authentication protocol for VANETs in multi-server environment, which achieves the goal that a user can do authentication and key agreement with all servers after his/her one-time registration. The proposed protocol constructs a simple authentication way by using elliptic curve cryptosystem, and decreases the sign and verification cost on the premise of providing privacy protection. The security proof proves the security of this protocol. Performance analysis shows that compared with the recent similar protocols, our protocol sharply decreases the computation and communication cost in the authentication and key agreement phase.