Design And Implementation Of Image Encryption Algorithm Based On Chaos Theory

In recent years,with the rapid development of science and technology,the application of computer has become increasingly extensive,and the security of multimedia information has become more prominent,and the security of multimedia information becomes more prominent.As an important carrier for people to obtain information,digital images are transmitted and stored in the network in large quantities.How to ensure the security of these image information becomes extremely important.However,due to the large amount of data,strong correlation and high redundancy of digital images,the traditional encryption algorithms are not suitable for the encryption of image information.Therefore,designing more secure image encryption algorithms has become an important research topic in the field of cryptography.Because the chaotic system has the characteristics of sensitivity,unpredictability and pseudo-randomness to the initial value,it is very consistent with the characteristics of cryptography.Therefore,chaotic encryption technology is widely used in the field of image encryption.This paper mainly studies the design and implementation of image encryption algorithm based on chaos theory.Firstly,the research background of chaotic image encryption algorithm is expounded,and the development status at home and abroad is studied.Secondly,the basic theory of chaos theory and cryptography is introduced.Then two image encryption algorithms are designed for the characteristics of digital images and the effects of limited precision.Algorithm 1 is an image encryption method based on two-dimensional(2D)double chaotic system.This method uses two-dimensional Logistic mapping and chaotic mapping based on modified Marotto theorem to generate two sets of chaotic real numbers respectively.After sequence optimization,XOR operation is performed to obtain the third group.The encryption sequence is separately diffused with the RGB component of the color image.This method not only has a large key space,but also can effectively resist statistical attack and noise attack.Algorithm 2 is an encryption algorithm based on chaos and bit plane.Three chaotic systems are mainly adopted.The system one is Arnold mapping,which is used to scramble the gray value position.The system two and the system three are the LC(Logistic-Cubic)system and the Henon mapping respectively,and use the Pythagoreantheorem to generate the encryption key.The key sequence and image matrix are decomposed into bits and the image bit plane is diffused.By analyzing the algorithm and security performance,the encryption effect is good,and it can resist different types of malicious attacks,and the security is greatly improved.At last,Matlab R2014 a is used as the tool to design the image encryption prototype system and realize the image encryption algorithm.