Research On Fast Chaotic Image Encryption Scheme With Simultaneous Permutation-diffusion Operation

Because of the initial value sensitivity,randomness and unpredictability of chaotic system,corresponding to the key sensitivity and the ability to resist violent attacks required by image encryption schemes,a lot of image encryption schemes based on chaos have been proposed.However,some existing encryption schemes can be cracked by cryptanalysis system because of the weak key sensitivity.In addition,due to the simple structure and small chaotic range of some classical chaotic systems,the encryption results are uneven and the information of the plain image cannot be completely hidden.Therefore,in this thesis,the chaotic system and specific encryption rules are improved to make the encryption scheme more secure and effective,and in order to meet the real-time transmission of multiple images,the encryption speed is also considered.The main innovations of this thesis are as follows:(1)A fast chaotic image encryption scheme with simultaneous permutationdiffusion operation is proposed.Firstly,our scheme can resist separated attack and chosen plaintext attack.The initial value of the current chaotic map is related to the previous encrypted pixels,which leads to the generation of dynamic keystreams related to the plaintext and then the security of encryption scheme is improved.In addition,the scheme has low time complexity and fast encryption speed.The reason is that in the whole encryption process,the pixel values are processed by row and column(row level or column level),which is conducive to the real-time transmission of multiple images.(2)A new two-dimensional hyperchaotic system is proposed and applied to image encryption.Firstly,we propose a new two-dimensional hyperchaotic system,and the performance analysis results show that the new chaotic system has strong initial value sensitivity and good randomness.Secondly,our scheme can resist noise attack,clipping attack and chosen plaintext attack.In addition,the scheme has low time complexity and fast encryption speed.The reason is that in the encryption process,pixel values are processed by pixel or by row and column.