Research On Physical Layer Encryption Based Communication System

Wireless communication networks have been widely applied in various fields,due to the inherent openness and broadcast nature of wireless communications,data is easily eavesdropped during transmission process.Thus,the security for wireless communication networks is required.The conventional communication encryption algorithm encrypts data at the data link layer or application layer.However,with the rapid development of hardware technology,many traditional encryption algorithms can not guarantee the security of communications any more.Physical layer encryption is a new secure communication technology that can overcome the inherent shortcomings of the traditional encryption algorithm and the new physical layer security technology,which encrypts and decrypts bit-stream data at Physical Layer,and achieving the purpose of securing communications.The main work of this paper are as follows:1.Aming at changing the method of generating chaotic seeds used in the physical layer encryption technology,and consolidate the overall security of the communication system,chaotic seeds can be generated through key-generation PHY technique.Firstly,collecting the CSI of the actual communication environment through Intel 5300 network card and csitools software,and using an adaptive quantizer quantizing the collected CSI data into binary bits-streams;the bits-streams are transformed into key sequences after information reconciliation and privacy amplification;Finally,the key sequences are evaluated by randomness test,key generation rate and key mismatch rate.2.In order to improve the security of low cost single antenna communication nodes in wireless networks under static channel,a physical layer secure communication scheme is proposed.Each digital modulated symbol is encrypted by a random key at the transmitter and decrypted at the receiver.The legal users exploit the synchronized chaotic sequence and the two-stage block interleaver to generate a complex random variable(random key).The modulated symbol is multiplied by the complex random variable(encryption)to imitate the Rayleigh fading of the channel at the transmitting end.The received symbol is divided by the identical complex random variable(decryption)to recover the transmitted message through the digital demodulation in the receiving end.Simulation results show that the bit error rate(BER)performance of the legitimate users is consistent with the theoretical value of the Rayleigh fading channel,while the corresponding BER of the eavesdropper is too high(about 0.5)to intercept any information.3.To achieve secure communication between legitimate users,a physical layer encryption scheme based on random rotation of the modulated symbol is proposed.By exploiting the random behavior and the reciprocity property of the wireless channel,the channel state information(CSI)shared between transmitter and legitimate receivers is used as an initial seed to generate chaotic sequence.The transmitter uses the chaotic sequence to rotate the modulated symbol to enhance communication security and to reduce eavesdroppers' ability to demodulated symbols correctly.Due to the fact that the eavesdropper does not posses any information about the legitimate channel because the channel response is unique to the location of the transmitter and receiver as well as the environment,the receiver is able to demodulate the random rotated symbols correctly while the eavesdroppers demodulate them erroneously.Simulation results show that bit-error-rate(BER)of the legal user matches theoretical results perfectly while the eavesdroppers' BER stays around 0.5.