Based On Lorenz-like Chaotic System And Its Application Of Image Encryption

After chaos was found to have complex dynamic behaviors,some scholars began to study its application field from the characteristics of chaos.Chaotic system has the characteristics of irregularity,non-periodicity,unpredictability and sensitivity to initial conditions,even if the initial value changes slightly,there will be great differences.Based on this,chaotic system is often used in image encryption.In this paper,two kinds of encryption algorithms are designed by using Lorenz-like chaotic system,and their security performance indexes are evaluated,and the advantages of encryption algorithms are compared and analyzed,which provides a theoretical basis for the application of chaotic system in image encryption.The main research work is as follows:(1)Through the specific definition of chaos in mathematics,the characteristics of chaos are described in detail.Based on the theory of image encryption,the characteristics,design and criteria of image encryption are summarized and discussed.(2)An image algorithm based on finite time synchronization of multi-scroll hyperchaotic system is designed.Firstly,the multi-scroll hyperchaotic system is used as the driving system to design its response system by finite time synchronization.Then,in the encryption algorithm,the chaotic sequence is generated by driving the system,and the picture is scrambled by circular cutting.Finally,the encryption algorithm is completed by bit plane diffusion.In particular,the bit plane algorithm needs to restore four bit planes to get plaintext,which will increase the difficulty of decryption.Through histogram,correlation coefficient and robustness testing,the proposed algorithm can better resist violent attacks and tailoring attacks.(3)A four-dimensional chaotic system is established by introducing cosine function into Lorenz system.Then through the complexity and bias enhancement analysis of the system,it is verified that the system has rich dynamic behavior,and the pseudo-random sequence generated by the system is tested by 0-1 test and the National Institute of Standards and Technology(NIST)test,which shows that the system has high pseudo-randomness.It is proved that the system is suitable for image encryption technology.Combined with this system,an image encryption algorithm based on hash and deoxyribonucleic acid(DNA)is designed.In this algorithm,the chaotic sequence is generated iteratively by the initial value of the system and the plaintext hash value.Scramble the plaintext sequence by reordering the index sequence.In the diffusion module,XOR and loop left shift are used to get the final ciphertext.Through simulation and security analysis,the algorithm has good encryption efficiency and security.It can resist exhaustive attack,plaintext attack,tailoring attack and noise attack.