Research Of Digital Image Encryption Algorithms Based On Multiple Chaos

Digital image is an important carrier of human communication and sharing in the Internet era,and it usually contains much personal privacy.It must be encrypted during the transmission to prevent to be used maliciously.With the basic theory of computer science and technology developing and becoming mature,on the one hand,digital images are not only stored and displayed in the manner of RGB color model,but also can it can also be showed under other different color models,such as HSV color model.On the other hand,thank to there are some characteristics in the digital image,such as a high redundancy,strong correlation and giant data volume,the traditional encryption schema is no longer applicable to encrypt digital image.In recent years,the fast development of chaos theory and traditional cryptography are deeply integrated to form chaos cryptography,which corrects the shortcomings of traditional image encryption algorithms.The multiple chaotic mapping structure in chaos cryptography plays a particularly important role in providing effective and secure encryption for digital images.Therefore,the purpose of this paper is to study the encryption of digital image in different color models based on multiple chaotic maps.First,building a general multi-chaos digital image encryption algorithm in the RGB color model,and then according to the chaos theory learned and practice experience,the algorithm can be improved,which includes the following aspects: making use of the whole operations combined addition with modulo instead of the local addition and modulus operations,in order to upgrade the password generator which generates the random sequence used for encryption,and this makes the operating time reduce to improve efficiency as well as provide strong random sequence of encryption;Each component from plaintext image is added by a ciphertext pixel information of the previous and the next component during the diffusion,which indicates that the information of a pixel from any component of the plaintext image can be able to diffuse all of pixels in other component.This enhances the diffusion effect,so that the security of the encrypted image is improved;In addition,according to the natural similarity between the hyperchaotic system Baker and permutation,the chaotic map is used to directly permutate the pixel positions of the image,so that provide more complex scrambling results can be provided and the overall security of the algorithm can be improved.What's more,the parameters of algorithm are modified due to the characteristics of the digital image in the HSV color model,so as to obtain the multi-chaotic digital image encryption algorithm based on the HSV color model.The algorithm provides a solution for encrypting images representing pixel values in the form of floating point Numbers.Finally,the algorithm directly converts the value of ciphertext image into the grayscale value of RGB image through modulus operations,which makes the algorithm retain the good encryption effect.Of the above two algorithms is perfected excellently and measured good data values in statistical characteristics,sensitivity,avalanche effect,the information entropy,the key space and time complexity.At the same time,it closes to the theoretical value,which means that the two algorithms have high resistance in most of malicious attack,such as brute force,differential attack,chosen-plaintext or known-plaintext attacks,cropping attack,noise attack,and statistical analysis attack.In addition,the two algorithms in this paper have different emphases.The chaotic image encryption algorithm in RGB color model is faster,while the chaotic image encryption algorithm in HSV color model has lower ciphertext histogram variance and stronger resistance to statistical attacks.The last but not least,compared with other literatures,the encryption performance of the algorithm in this paper also has certain advantages.In general,the algorithm proposed in this paper has a good encryption effect,and it can be used to encrypt digital images in other color models by adjusting to parameters,therefore it also contains a certain degree of universality.This shows that the proposed algorithm has great potential for development and broad prospect for its application and certain economic and social value.