Multiple-image Encryption Algorithm Based On Chaos And DNA

With the development of multimedia and big data technology,the multimedia information on the Internet presents a trend of massive growth.However,while the Internet is open and convenient,it also brings threats to the security of multimedia information.Among them,digital images are most frequently used in communications,medicine,remote sensing,etc.Once they are monitored,stolen and tampered with by criminals,they will bring irreparable losses to the country and individuals.Therefore,protecting the information security of digital images is an important subject of cryptography.Chaotic systems have natural cryptographic properties and are widely used in the field of image encryption.However,a single chaotic encryption algorithm proved to be weak in security.Deoxyribonucleic Acid（DNA）has a high degree of parallelism and storage density,which can improve the time and space complexity of the algorithm.To solve the defects of multi-image encryption algorithm in crypto-graphic security,execution time and encryption capacity,two multi-image encryption algorithms based on chaos and DNA are proposed.The main research work is as follows.A multi-image encryption algorithm based on three-dimensional（3D）scrambling model and dynamic DNA coding is proposed.First,the hash values of multiple plain images are used to generate the key stream of the algorithm,and the required chaotic sequence is iterated.Secondly,multiple plain images are constructed as 3D image cubes,and chaos and generalized Zigzag transform are used to establish a 3D scrambling model and scramble the image cubes.Then,according to the specified coding and operation rules,dynamic DNA coding and DNA operations are performed on the scrambled images by using chaotic sequences.Finally,a dynamic DNA decoding operation is performed to obtain the final encrypted image.Experimental analysis shows that the algorithm key space is 2⁶²⁸,which is sufficient to resist exhaustive attacks,the information entropy is 7.9998,the batch encryption time is 1.71 seconds,and the encryption capacity is not limited,which can effectively ensure the security of digital image data.A multi-image encryption algorithm based on multi-directional scanning scrambling and DNA mask operation is proposed.First,multiple plain images are formed into an image cube,and the initial key stream is generated by using the hash values of multiple plain images and external parameters,and is substituted into the chaotic system to generate the required sequence.Second,the image cube is scrambled using chaotic sequences and multi-directional scanning.Then,use the chaotic sequence to generate mask matrix and regular matrix,and perform dynamic DNA coding on the mask matrix and scrambled results.Finally,DNA operation is performed on the encoded image cube and mask matrix according to the rule matrix,and the final encrypted image is obtained through DNA dynamic decoding.Experimental analysis shows that the algorithm key space is 2⁴¹⁵,the information entropy is 7.9998,and the batch encryption time is 1.64 seconds.The proposed algorithm has the advantages of security,efficiency and robustness,and can resist brute-force attacks,statistical analysis attacks and chosen-plaintext attacks,and is suitable for the protection of batch digital image information.There are 119 figures,15 tables and 95 references in this thesis.