| With the development of automobile industry and the improvement of economic level,the number of vehicles is increasing.The situation causes serious traffic congestion and frequent traffic accidents while bringing convenience to people.In recent years,people’s demands for driving safety and comfortably become more and more urgent which bring us the emergence of VANETs(vehicular ad hoc networks).And it has become a research hotspot that the government,research institutes and auto industry pay close attention to.VANETs adopt the wireless communication protocol,which means that malicious attackers can easily modify the message sent from legal vehicles,or even send forged information.It is obvious that the malicious attackers can endanger the traffic if no reasonable message authentication scheme is deployed.Therefore,message authentication is necessary for vehicles,which means that,after receiving a message,the receiver of the message must check the integrity and reliability of the message.Only the message is integral and reliable,it could be processed later.Therefore,it is necessary to design an efficient and secure message authentication scheme for VANETs.However,the road safety information sent by vehicles is not enough to ensure traffic safety.Obtaining relevant information from infrastructure including roadside units,which involves data downloading research in VANETs,is also necessary.In some cases,vehicles do not want to disclose their data download requests to any third party.From the statistical point of view,the data downloading requests from vehicles approximate the normal distribution,that is,most requests aim to a small part of the data.And we can use the phenomenon to design an efficient data downloading protocol without sacrificing single user request privacy.In this thesis,we will focus on the scenario of message authentication and data cooperative downloading in VANETs,and combine the idea of edge computing to design two efficient and security schemes.The work and contributions of this thesis include the following aspects:1.This thesis proposes an efficient message authentication scheme based on edge computing.In the scheme,the system selects a part of vehicle as edge computing vehicle(ECVs)according to the position and storage capacity of the vehicle.ECVs perform coordinated authentication on the messages sent by the surrounding vehicle,and then send the authentication result to the road side unit(RSLU)for verifying.If legal,then the RSU would broadcast the authentication result to the surrounding vehicles through the Cuckoo filter.Thus the vehicle only needs to query the legitimacy of the message with a very low query overhead to achieve the purpose of message authentication.The security analysis part proves that the proposed scheme meets the security requirements of VANETs.The performance analysis shows that compared with the traditional scheme,the authentication efficiency of the whole system in the proposed scheme is very high and the load on the RSU end is low,which makes the scheme more suitable for deployment in the real VANETs scenario.2.This thesis proposes a collaborative downloading scheme based on edge computing.In the present scheme,the vehicle encrypts the content download request and sends it to RSU and the content server,respectively,and the content server will transmit the requested content to the vehicle through the roadside unit.At the same time,when the roadside unit collects a certain number of requests,it can reveal the received encrypted requests to get the most popular content and pre-download this content to ECVs which are chosen from vehicles that have relative strong storage power and suitable position.In this way,if one vehicle has a request for accessing any of the most popular content in the future,it can directly download the content from the surrounding ECVs.The security and performance analysis show that our scheme can achieve high efficiency without sacrificing user privacy. |
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