Research On Physical Layer Covert Authentication Technology Based On Fragmented Transmission

In recent years,as wireless communication technology has brought many conve-niences to people’s lives,people have paid more and more attention to security issues in communication.The openness of the wireless network makes wireless access anytime and anywhere convenient,but at the same time the openness also makes it vulnerable to inter-ference attacks and eavesdropping.Therefore,in order to avoid illegal access and attacks by unauthorized users,wireless communication systems usually need to authenticate the accessing users.This process is called authentication.Most authentication mechanisms(for example,digital signatures and certificates)exist above the physical layer.Although some mechanisms(for example,spread spectrum communication)exist in the physical layer,they usually increase bandwidth costs.This paper studies a physical layer over-lay transmission covert authentication technology based on a watermarking mechanism.By modulating and superimposing a low-power encrypted authentication watermark sig-nal on the message waveform,the authentication information and the message data are transmitted at the same time without adding additional bandwidth.The signal adds au-thentication information to defend against malicious attacks by third-party illegal users and ensure security in the communication process.This article first introduces the spectrum sharing technology based on cognitive ra-dio,and applies its underlying transmission technology to the content of this research,that is,overlapping transmission technology;then it briefly introduces the basic overview of authentication and secure communication in communication;next;The hidden authen-tication scheme based on Hash-based physical layer overlay transmission proposed by Gunjan Verma et al.is introduced in detail.The core idea of this scheme is to first gener-ate a low-power authentication watermark signal at the transmitter.The signal is generated by Hash mapping from the message signal data and the pre-synchronized shared key of the sender and receiver,and then the authentication watermark signal is embedded To the message signal,overlap transmission.Utilizing the characteristic of Hash mapping and the superposition characteristic of the low power of the authentication watermark signal,this scheme can encrypt the authentication watermark signal and achieve a certain effect of covert communication.However,this solution still has many problems,such as sensitivity to signal errors generated during the transmission process.This is mainly due to the char-acteristics of the Hash mapping algorithm.A small change in the input data will lead to a complete change in the output data;authentication watermark signal The concealment is poor.In the traditional scheme,the authentication watermark signal is continuously transmitted with the message signal,which leads to the introduction of obvious cyclosta-tionary and statistical characteristics in the authentication watermark signal.The attacker can use this feature to easily detect the existence of the authentication watermark signal,so as to take targeted attack methods;the authentication frequency is too high,and the resource consumption is high,mainly because the transmission of the authentication wa-termark signal is in time There is no sparseness,which leads the receiver to continuously and uninterruptedly authenticate the received signal.In view of these shortcomings of the traditional Hash-based authentication scheme,this paper discusses the physical layer overlapping transmission hidden authentication scheme based on the fragmented transmission of the watermark signal on the basis of the traditional scheme,from the selection of message signal mapping data segment,trans-mission authentication The segmentation processing of the right watermark signal and the selection of the position of the authentication watermark signal are divided into three levels to fragment the transmission of the authentication watermark signal,which is equivalent to a further three-level encryption process,which makes the authentication signal more diffi-cult to be illegally processed.The three-party users detect and recognize that the security and concealment of the authentication signal transmission are further improved,thereby also improving the reliability of the entire authentication scheme.From the simulation re-sults,the physical layer overlapped transmission hidden authentication scheme discussed in this article is based on fragmented transmission.By fragmenting the authentication wa-termark signal,it improves its time sparsity,greatly weakens the statistical characteristics,and improves The anti-interception ability of the watermark signal not only has good au-thentication performance,but also has strong concealment.Finally,the time complexity of the hidden authentication scheme of the physical layer overlapping transmission based on the fragmented transmission of the watermark signal is analyzed,and the selection of the message signal mapping data segment,the segmentation processing of the transmis-sion watermark signal,and the selection of the location of the authentication watermark signal are also carried out.Level,analyze the complexity of traversing all possible water-mark signals,and give the order of magnitude of time complexity,which proves that this scheme can effectively prevent third-party illegal users from eavesdropping and cracking,and ensure the security of the entire authentication system.