Research On Security Quantification Theory And Protection Technology Of Vehicular Ad Hoc Networks

Vehicular Ad Hoc Networks(VANETs),special form of Mobile Ad Hoc Networks(MANETs),are applied in traffic.Recently,as wireless technology and automotive industry develop rapidly,VANETs have come up into people's horizons and been studied widely,therefore,VANETs security issues become the focus of the public.The paper mainly includes two parts: in the first part,we objectively quantify the security level of VANETs so as to adopt proper security protection mechanisms(SPMs)accordingly;in the second part,we propose a valid model to guarantee confidential communications of VANETs so as to avoid issues such as privacy disclosure and data tampering,etc.VANETs can be viewed as a typical context-aware system where the experienced context frequently varies as vehicles move along road,e.g.,signal-to-noise ratio(SNR),velocity,and traffic flow,which makes topology and link changed rapidly,so security level fluctuates all the time.Regarding the highly dynamic nature of VANETs,the paper views the security level as its inherent property that is only correlated with the user's behaviors and the situated context and independent of the suffered attack ways or the suffered attack strength.Due to VANETs are time-varying system,the paper proposes a formalized methodology to especially quantify the security level in real time in inhomogeneous continuous time Markov chain(ICTMC).The VANETs is divided into 7 states and different states can mutually transit from one to another.Security level is obtained through predicting the stable probability of staying in the security state.The ICTMC can be described through its embedded inhomogeneous discrete time Markov chain(IDTMC),representing the sequence of states traversed,together with an inhomogeneous Poisson process(IPP),indicating the jumping times.The paper also conducts the extensive numerical calculations and empirical analysis to comprehensively investigate the response of the proposed security quantification framework to the various combinations of the concerned parameters.The results show that the proposed framework is capable of capturing the real-time security level adaptively to the vehicular context and provides a dependable decision basis to SPMs.Meanwhile,VANETs are open system,allowing various types of mobile terminals dynamically to join and leave.Besides,owing to the broadcast nature of wireless mediums in V2 V and V2 I,the wireless transmission is readily overheard by unauthorized users for interception purposes and is thus highly vulnerable to eavesdropping attacks.To attain the confidential transmission,the paper proposes a method of assuring physical-layer security,i.e.security capacity is greater than zero always.To avoid the case that channel capacity of wiretap link(between transmitter and eavesdropper)is larger than that of main link(between transmitter and legitimate receiver),i.e.security capacity is zero,a Multiple-Input Multiple-Output(MIMO)system where a transmitter,a legitimate receiver,and an eavesdropper coexist is considered.Firstly,calculate the optimal covariance matrix of main channel by generalized singular value decomposition(SVD)and water-filling power allocation;Secondly,ensuring the minimum signal to interference plus noise ratio(SINR)of the legitimate receiver,the transmitter devotes the remaining available power to transmitting the artificially generated noise into the null space of the main channel in order to worsen the quality of wiretap channel;finally,conduct the extensive numerical analysis to comprehensively investigate the efficiency of the proposed method concerning various combinations of parameters including the transmit information signal power,the number of transmitter antenna,etc.and the results show that the proposed method significantly improves secrecy capacity while securing wireless communication.