Research And Application Of Multiple Security Levels Video Encryption Algorithms Based On Chaos Theory

With the rapid development of network technology and the upgrading of hardware devices,digital video has been widely used in all aspects of social life.Video security issues in the network transmission have also attracted more and more attention.As an important means to solve the problem of video transmission security,the study of video encryption technology has aroused the interest of many scholars.H.264 is the most widely used video codec technology.H.264 video encryption algorithm has become the focus of the current video encryption research.At the same time,chaos theory is widely used in information security because of its unpredictability,ergodicity,parameter and initial sensitivity.Therefore,the study of H.264 video encryption algorithm based on chaos theory has important theoretical significance and application prospects.In this thesis,we study H.264 coding framework,analyze the characteristics of H.264 syntax elements and its influence on security.Based on these works,we select quantization coefficients,intra prediction modes and motion vector residuals as encryption syntax elements.Also,we deeply analyze the encoding details of encryption syntax elements and propose corresponding encryption and decryption method.In order to meet the different security requirements of different application scenarios,we propose a multi-security level video encryption algorithm based on the analysis results of encryption elements and encryption methods,using a random key generator based on Logistic chaotic map.We study the properties of two-dimensional Henon chaotic system,the chaos generation process and the existing security problems.An improved Henon chaotic system is proposed by using a modified Feigenbaum transcendental equation to perturb the dimension of the original Henon chaotic system.And a random sequence generation scheme which can be directly used for video encryption is designed based on the improved system.Based on the random sequence generation scheme we propose a video encryption algorithm of I frame.The simulation results show that the multi-level encryption algorithm can meet the requirements of security in different application scenarios,and it has good performance in terms of the encryption efficiency and the consistency of the compression ratio while ensuring the format compatibility.The modified Henon chaotic system exhibits hyperchaotic properties and is superior to the original Henon chaotic system in terms of key space,ergodicity,initial sensitivity,and system complexity.The sequence generator based on the modified Henon system has good randomness and low correlation.The video encryption algorithm of I frame makes full use of the ciphertext diffusion effect and has good encryption effect.