Design Of Image Encryption Algorithm Based On Logistic Chaotic Sequence

With the rapid development of multimedia technology,images become one of the main carriers of information,and their security in transmission and storage is increasingly important.The traditional single image encryption algorithm has slow operation speed,low security,and does not meet the requirements of network real-time and security.Finding new image encryption methods has become the focus of current information security research.Chaotic motion has the characteristics of initial value sensitivity and strong randomness,which is always used for digital image encryption,so chaos encryption algorithm has become the focus of image encryption research.Firstly,based on the research of chaos theory and cryptography theory,this thesis proposes a chaotic image encryption algorithm that combines pixel scrambling with pixel diffusion.In the aspect of pixel scrambling,the Arnold transformation times are obtained by comparing the scrambling degree of Arnold transformation in different rounds,and the application scope of Arnold transformation is extended.The final image scrambling scheme is obtained.In the aspect of pixel diffusion,a new piecewise Logistic chaotic map is proposed,and the sequence generated by LFSR is used to disturb the sequence generated by the piecewise Logistic chaotic map.The method improves the randomness of the segmented Logistic chaotic sequence and makes it more suitable for image encryption.Then,the chaotic image encryption algorithm of this thesis is implemented by using a hardware circuit design.In the process,it is important to focus on the hardware implementation of the Arnold function and the segmented Logistic chaotic map.Finally,Vivado,Modelsim and MATLAB tool is used to perform functional simulation and verification of the design.In this thesis,Xilinx Virtex-7 series VC707 model FPGA development board is used to verify the image encryption and decryption system.The results show that the horizontally adjacent pixel correlation of the image encryption scheme proposed in this thesis is 5.186×10^-4,which is less than 0.01,which can meet the requirements of resisting statistical attacks.At the same time,the density information entropy is7.9980,which is close to a random image.Its information entropy is 8.And the key space can reach9.189×2¹⁰⁹,which is able to resist brute force attacks.Therefore,the work and results of this thesis have reference significance for image encryption.