Research On Key Generation At Physical Layer In Vehicle Commnunication

As one of the main applications of intelligent transportation systems,vehicular ad-hoc networks(VANETs)have received a lot of research in recent years.VANETs realize the mutual communication between vehicle and person,vehicle and vehicle,vehicle and roadside infrastructure,so that information can be transmitted quickly and effectively,and road traffic conditions have been improved.Among them,vehicle to vehicle(V2V)communication is the communication between vehicle and vehicle,which means that the vehicle and its surrounding vehicles communicate with each other in real time in a multi-hop manner,which is the focus of this article.V2V communication is based on a common channel to realize the transmission and reception of information,so there is a problem of information security.Encrypting and decrypting the message through the key is a feasible solution to the problem.At this time,it is important to ensure that both parties of the legitimate vehicle,Alice and Bob,hold the same key.However,traditional encryption schemes based on cryptography require a key distribution process to be implemented.In addition,the security of such schemes is mostly based on computational complexity.However,the physical layer key generation scheme can resolve the above limitations.In the scheme,using the inherent randomness of the channel,channel reciprocity and spatial decorrelation,the randomness of the fast fading channel(with noise and interference at the same time)experienced by the vehicle as the source is used to detect the channel and obtain data samples.Then through pre-process,quantification,information reconciliation and privacy amplifcation steps to generate a shared key.Among them,the channel reciprocity allows Alice and Bob to obtain highly correlated data samples through channel detection,and the spatial decorrelation allows the adversary to obtain inconsistent data samples,ensuring that the adversary cannot obtain the shared key.Therefore,this scheme avoids the key distribution process and realizes information theory security.This paper proposes a physical layer key generation scheme that can be applied to vehicle communication.The main tasks are:1.In view of the many divergences between the channel detection samples of legal vehicles,a pre-process scheme based on Empirical Mode Decomposition(EMD)is proposed.The difference here means that the data corresponding to the same index of the two samples will be quantized into different bits in the later stage.The scheme uses EMD algorithm to reduce these differences and reduce the bit mismatch rate.2.In view of the loss of randomness in the pre-process stage and the disclosure of some information about the key in the information reconciliation stage,a high-performance privacy amplification algorithm is proposed.Based on the Linear Feedback Shift Register(LFSR)to generate the Toeplitz matrix,the algorithm divides the reconciled key into multiple batches.Each batch of reconciled keys is processed in parallel by the Toeplitz matrix to generate a shared key.This algorithm reduces the computational complexity and improves the randomness of the shared key.3.A physical layer key generation scheme that can be effectively applied to vehicle communication is proposed.Firstly,the EMD pre-process scheme is applied to process the data samples.Secondly,using the multi-bit quantization scheme to map the available data into a binary bit sequence.Thirdly,the Low Density-parity Check-code(Low Density-parity Check-code,LDPC)is utilized to correct the inconsistent data between the samples of Alice and Bob.Finally,applying a privacy amplification algorithm to improve the randomness of the shared key.Experimental results show that the scheme can achieve the expected good performance.