The Research Of Color Image Encryption Algorithms Based On Chaos And Gyrator Transform

With the development of Internet and multimedia communication technology,multimedia communication technologies such as image,voice,video and so on appear constantly.The promotion of multimedia technology has greatly influenced the way of working,living and study.As an important component of multimedia technology,it may carry sensitive information.So the security of storage and transmission is essential.Therefore how to ensure the security of image data and improve the efficiency of encryption algorithm is the main direction of the current research.Large amounts of data,strong correlation of adjacent pixels,high redundancy are the characteristics of digital image,so the encryption algorithm of traditional text data is no longer suitable for digital image encryption.In view of that the sensitivity to initial value and ergodicity are the favorable characteristics of chaotic system,the image encryption algorithm based on chaos has become one of the mainstream technologies in image encryption.This paper introduced the status and trends of digital image encryption technology both here and abroad,the basic theories of chaos,gyrator transform and its application in image encryption.On the basis of current algorithm researches,two color image encryption algorithms are proposed,and this paper mainly has these two parts:1.A color image encryption algorithm based on coupled map lattice was proposed.Firstly,one-dimensional robust chaotic map was used to scramble three matrix of the color image by bit operation.Then,processed matrix were divided into blocks and completed the round encryption,which realized diffusion encryption in component and decreased relevance of the same position corresponding to three components.Initial values of system were obtained by combining logistic map and plaintext,which effectively improved the sensitivity of the keys and plaintext.Theoretical analysis and experimental results show that the algorithm proposed has better security and encryption effect.2.A color image blocks encryption algorithm based on gyrator transform was proposed.Three matrix of the color image were recombined and obtained two recombinant matrix in pretreatment.They were divided into two parts,which were regarded as the input of Gyrator transformation and double random phase encoding in two random phase mask.Plaintext matrix were taken place of random white noise function,which reduced the difficulty of key storage.The algorithm fully confused the plaintext information.Selecting the appropriate number of iterations,which improves the security performance,ensures the integrity of the plaintext information at the same time,effectively ameliorates the decrypted image distortion problem which caused by computer precision.The experimental results show that the algorithm has good security and encryption efficiency.