Research On Efficient Authentication Schemes With Conditional Privacy-preserving For VANETs

As a special type of mobile ad-hoc networks,a vehicular ad-hoc network(VANET)is composed of three major entities: vehicles,road side units and the trusted authority,which build up a distributed cooperative system.VANETs are performed to realize traffic efficiency,traffic safety and provide quality services to vehicles,which play important roles in the construction of intelligent transportation systems.However,VANET technology faces many challenges in practical application.On the one hand,its unique features,include high mobility and rapid network topology change,raise the requirements for the computational performance of the message authentication scheme.On the other hand,open wireless communications also make it vulnerable to multiple types of security attacks.In addition,it is also necessary to provide conditional privacy-preserving for vehicles to achieve a balance between reliability and anonymity.However,current schemes still have problems in terms of security and efficiency performance.Aiming at the above issues,we proposed two authentication schemes in this thesis after researching on various message authentication protocols for VANETs.The main research contributions are as follows:(1)An identity-based anonymous authentication protocol with temporary group key is proposed in this thesis.Firstly,the group key distribution process is completed through a synchronous temporary group key in the proposed protocol.Secondly,by optimizing the parameter structure,this process does not depend on the requirement of deploying the system private key to the vehicle’s TPD in the traditional solution,which improves the robustness of the system.Complex bilinear operations are avoided in the message authentication process.Scalar multiplication operations of elliptic curve are also reduced.And a batch authentication method is provided,which effectively improves the authentication efficiency.The non-repudiation of batch verification is ensured by applying small index test technology.(2)A chaotic map based efficient authentication scheme is proposed in this thesis,in which high-efficiency Chebyshev chaotic map and symmetric encryption algorithms are applied instead of complicated bilinear pairing and elliptic curve cryptographic operations for scenarios with high vehicle density.The key agreement process between the vehicle node and the RSU is safely completed in the proposed scheme without any group signature under the semi-group property of Chebyshev polynomial.An online parameter update method is also provided.Secondly,a temporary shared key distributed by RSU is constructed to realize efficient anonymous authentication between vehicles.Vehicle nodes do not need to verify a large revocation list for each tuple,and the revocation of vehicles will not affect the performance of the group.Finally,the results of security analysis and performance evaluation for two proposed schemes in this thesis based on existing similar schemes are respectively given.Compared with the best one in comparison schemes,the first protocol increases the number of message batch authentication per second by 0.8 times while maintaining a low communication overhead.The second scheme saves about 5% of the computational overhead for each entity in the key agreement phase,and about 54% in the message authentication phase with lightweight communications.