| Digital images are one of the common forms of media data and are widely used in various fields such as military,medical and commercial.As pictures are spread on the Internet,the personal privacy or confidential information contained in them also faces the risk of being leaked or tampered with.Therefore,it is necessary for us to ensure the security and integrity of images during transmission and storage.In this paper,two new digital image encryption algorithms are proposed based on the defects of current image encryption algorithms such as noise resistance,weak cropping attack capability,and low DNA encryption efficiency.The specific research contents are as follows:(1)A chaotic image encryption algorithm based on compressed sensing and DNA coding is proposed.Aiming at the shortcomings of current image compression and encryption algorithms,which have weak resistance to noise and cropping attacks,different compression and encryption methods for high-frequency and low-frequency parts are proposed.Specifically,in the compression stage,only the high-frequency part is compressed,and the low-frequency part is retained;in the encryption stage,DNA coding is introduced,and the method of dynamic DNA encoding and decoding is adopted.DNA operations are performed between the DNA blocks of the three high-frequency parts,which effectively improves the algorithm.security.Furthermore,in compressive sensing,a new construction method of measurement matrix is designed using Chen chaotic system.The sha-256 algorithm is used to obtain the hash value of the plaintext image,which is used to generate the initial state of the chaotic system and serve as the algorithm key,achieving the effect of one-time pad.The experimental results show that the algorithm has good robustness while maintaining the security performance,and has good application potential in secure image communication.(2)A chaotic image encryption algorithm based on DNA parallel coding is proposed according to the shortcomings of existing algorithms that DNA encryption takes too long and the ability to resist statistical attacks is not strong.The structure of the entire cryptosystem is a scrambling-diffusion structure.With the help of the two-dimensional hyperchaotic system SLIM,the image matrix is scrambled sequentially by row and column to achieve a good scrambling effect.The introduction of DNA dynamic coding enhances the security performance of the algorithm.In addition,a DNA-level Zigzag scrambling operation is proposed to enhance the security performance of the algorithm.The DNA operations in the whole process are all parallel operations,which effectively improves the efficiency of the image encryption algorithm.Experiments show that this scheme has large key space,strong key sensitivity,basically zero correlation between adjacent pixels of encrypted images,and has good robustness against differential attacks,noise attacks,and cropping attacks. |
