Research On Fast Image Encryption Algorithm Based On Chaotic Systems

With the rapid development of communication technology and computer technology,people pay more and more attention to the problem of image information security.Image encryption is the most effective way to ensure the secure transmission of confidential images in public information channels.The classical encryption methods based on text data(such as DES and AES)are no longer suitable for image encryption,because the image has the characteristics of large volume,high data redundancy and strong correlation between adjacent data.Cryptographers have found that chaotic system has some inherent attributes such as extreme sensitivity,aperiodicity and ergodicity to initial conditions and parameters,which to some extent correspond to the attributes of image encryption system.In recent years,a large number of image encryption systems based on chaotic systems have emerged.Compared with the traditional encryption method,the image encryption method based on chaos has higher security and better encryption effect.This paper first analyzes the research background and significance of chaotic image encryption,then analyzes the research status of chaotic image encryption,and summarizes the shortcomings of several common chaotic image encryption systems.Through analysis and research,combined with the latest chaos theory,a new image encryption algorithm with higher encryption and decryption efficiency and better security is designed.The content and main work of this paper include the following two aspects:Firstly,a fast image encryption algorithm based on logistic map and hyperchaotic Lorenz system is proposed.Use logistic map to scramble the image pixel position,then use three pseudo-random sequences and hyperchaotic Lorenz system to scramble the image.The simulation results show that the image encryption algorithm is a good image encryption algorithm with the characteristics of large key space,uniform ciphertext image distribution and low correlation between adjacent pixels.Then,based on the piecewise linear chaotic mapping PWLCM and cubic S-box,an image encryption algorithm which is the same as the decryption algorithm is proposed.Three sequences are generated by PWLCM mapping.After finding the stereo S-box,the images are spread forward,scrambled,spread backward and rotated 180 degrees four times to generate ciphertext images.The simulation results show that the new image encryption algorithm has the advantages of fast encryption / decryption speed,large key space and strong anti differential attack ability.