Research On Image Encryption Technology Based On Chaotic Mapping And DNA Coding

With the rapid development of computer and network technology,digital images are widely used in biomedicine,military security,aerospace and other fields,and have received great attention.Digital images have the characteristics of large amount of data,strong correlation between adjacent pixels,and high feature redundancy.When traditional information encryption technology encrypts images,it will lead to low encryption efficiency and affect the image format.Therefore,how to ensure the safe storage and transmission of digital images has become a great challenge in current image processing research.Chaos,a typical nonlinear system at present,has the advantages of initial value sensitivity,non-periodicity and unpredictability,and meets the design requirements of image encryption systems.Taking the basic theory of chaos as the starting point,this thesis studies the image encryption method combined with the DNA coding operation.The main contents are as follows:Aiming at the low complexity of low dimensional chaotic system,the motion law is easy to be predicted,the designed image encryption scheme has small key space and insufficient anti attack ability,a new image encryption algorithm based on fractional order simplified Lorenz chaotic map and DNA coding is proposed.First,plaintext images are layered and DNA encoded,and then scrambled;Secondly,using the average pixel value of the plaintext image after stratification as the initial value,the fractional order chaotic sequence is solved,and the DNA matrix is generated and the DNA operation rules are used for operation;Finally,the ciphertext image is obtained by DNA decoding.In addition,in order to decrypt the image,the average pixel value of each component is hidden in the last pixel of each component matrix,which further improves the security of the algorithm.The simulation experiment and security comparison analysis comprehensively evaluate the performance of the algorithm from the correlation of adjacent pixels,information entropy,resistance to differential attacks,etc.The results show that the encryption and decryption effect of this method is good.Aiming at the problems of single DNA coding and operation mode and simple structure of chaotic system in the current image encryption algorithm based on chaotic system and DNA coding,this thesis designs a new 1-DST chaotic map,and an image encryption algorithm combining multiple chaotic systems,DNA coding and twodimensional compression sensing is proposed.Firstly,the plaintext image is processed through compressed sensing technology,and a random matrix is generated by using 1-DST chaotic mapping,and the generated random matrix and each component of the image are divided into blocks to perform DNA encoding.Secondly,perform DNA operations and decoding operations on matrix blocks.Finally,combine matrix blocks and image components to obtain ciphertext images.The encoding,decoding and DNA operation processes in the algorithm are determined dynamically and randomly by the Jerk chaotic system.At the same time,the new chaotic map iteratively generates three different chaotic sequences,which are used to perform DNA operation,row permutation and column permutation on the plaintext image respectively,which enhances the scrambling effect of the ciphertext image.Experiments show that the algorithm not only has large key space and strong sensitivity to keys,but also can effectively resist noise attacks and tailoring attacks.