Research On Digital Image Encryption Algorithm Based On Chaotic Technology

With the development of information technology,the network channel security in the multimedia information is faced with all aspects of challenge.Digital image is a common expression used in people's daily life,and its encryption becomes the focus problem.All kinds of encryption algorithm make great progress.Chaos theory is a great discovery in recent years,whose high sensitivity and pseudo random orbit characteristics provide the possibility for combination of cryptography.Based on the present development status of digital image encryption and existing prior chaos model,the thesis analyzes the characteristics of one dimension to high dimensional chaotic trajectory and does the following work.At first,the thesis expounds the cryptography and chaos theory to their respective theoretical foundation,and introduces the characteristic of chaos and engineering criterion.It analyzes the commonly used several kinds of one-dimensional to high-dimensional chaos model,and gives the index analysis of image encryption.Secondly,we put forward a novel image encryption algorithm based on compound chaotic system and Deoxyribonucleic Acid(DNA)sequence coding.Due to the fact that one-dimensional chaotic map has defects of discontinue control parameter range and uneven distribution of chaotic sequence,the thesis gives the compound chaotic improvement program,and makes the detailed mapping of the bifurcation diagram and Lyapunov index analysis.Then the calculating method of DNA sequence coding improved encryption method is proposed,which designs encryption feedback mechanism based on compound chaos and DNA exclusive or computing.The experiments show that the proposed algorithm has good encryption effect,expands the key space,and increases the difficulty of deciphering attack.The simulation results verify that the algorithm has good performance against the attack via various index analysis.Finally,we put forward an improved ART encryption algorithm combined with hyper chaos system.The thesis expounds on the two-dimensional phase mask Arnold system scrambling encryption model.Due to the fact that the ART encryption effect and efficiency are poor,which is not suitable for the square image encryption,the thesis introduces the hyper chaotic Lorenz system.It combines with the characteristics of ART scrambling encryption and uniform distribution of hyper-chaos sequence characteristics,and uses the block encryption and spread confusion encryption methods.All aspects of the simulation analysis indicate that the improved algorithm has good statistical properties and encryption effect.