Image Encryption With Hyper Chaotic Map

Chaotic image encryption is a kind of technique of image encryption based on the pseudo randomness and the extreme sensitivity to initial value of the chaos.The basic structure of the traditional chaotic image encryption algorithm is: scrambling,substitution and diffusion,where the scrambling of the pixel position is achieved through the random nature of the chaotic sequence,and the substitution and diffusion of pixel value is realized by the nonlinear operation between the plain text,the cipher text and the chaotic sequence.In this paper,we first summarize the theory and characteristics of chaos,and analyze several typical chaotic and hyper chaotic systems,then study the present situation of the chaotic image encryption,and lastly analyze the security of the traditional chaotic image encryption algorithm in detail,to find out that the traditional chaotic image encryption algorithm has the disadvantages of small key space,complex encryption process and so on.Aiming at the problems,the main work of this paper includes the following three aspects:1.A global bit-scrambling algorithm is proposed.Based on the principle of pixel position scrambling,pixel value substitution and diffusion,combined with the row scrambling,column scrambling of pixel position and the binary bit-scrambling of pixel value,we propose an algorithm of global bit-scrambling:the image is globally bit-scrambled after being converted into a one-dimensional binary sequence.The pixel value is changed at the same time of global bitscrambling,and the bits of each pixel are randomly spread across the image.As a result,the scrambling,substitution and diffusion of pixels are realized at the same time during the global bit-scrambling,which has a very high computational efficiency.2.A new hyper chaotic image encryption algorithm based on global bitscrambling is developed.Using the hyper chaotic system to generate the chaotic sequences,which are used to realize the global bit-scrambling of the image.Then using the new pixel value substitution encryption formula,to encrypt the image by two rounds of substitution encryption operations,in order to further enhance the anti-attack of the encrypted image.Experimental analysis and simulation results show that the key space of the algorithm is very large,and it has good statistical properties and differential characteristics.3.A new image encryption algorithm based on cross-utilizing hyper chaos and DNA computing is developed.DNA computing is a newly developed computational method.For DNA computing has the characteristics of simple,fast,flexible and changeable,we propose to combine the hyper-chaotic sequence and DNA sequence together.After DNA encoding of the image and the chaotic sequence,perform DNA computing to encrypt the image.And the security of the algorithm is verified by the key sensitivity analysis,statistical analysis,differential analysis,correlation analysis of adjacent pixels,information entropy and robustness analysis.