Research On Color Image Encryption Algorithm Based On Chaos System And DNA Coding

Times have changed,science and technology have advanced,network communication methods have diversified,and people's work and life have become more colorful.However,there are still some security concerns that are inevitable.There are many ways to express information,such as documents,voices,images,etc.Among them,digital images are important communicators in People's Daily lives,and almost all information is transmitted through digital images during information between people.This is because when information is conveyed through digital images,it can not only vividly express the visual effect of the image,but also convey the content of the information effectively.Some important information is not only related to personal information,company secrets,etc.,but also to national information security,so certain important information must be protected in the process of sending messages in the context,image encryption is a good choice.It covers various fields such as mathematics,computer science,information theory and so on,and is a rich encryption method.A long time ago,texts were widely studied as objects.With that encryption method,several successful research results have been achieved.Unlike images,text is not affected by proprietary factors such as excessive data volume,high redundancy,etc.Therefore,some existing Encryption methods,such as DES(Data Encryption Standard)and AES(Advanced Encryption Standard),cannot meet the needs of current image Encryption.Chaos theory was proposed later,which was widely used in image encryption due to its intrinsic properties and close correlation with encryption.However,researchers have found that due to the limitations of computer accuracy,the numerical realization of chaotic maps will eventually experience short periodicity,which would bring some security risks to some encryption algorithms that apply chaos.To avoid the short term problem of numerical realization of chaos,long-term high-order chaos is often widely introduced into the image encryption.However,as a separate encryption method,whether it is low-dimensional chaos or high-dimensional chaos,it is less secure and prone to cracking.To improve cryptographic security,the researchers found that DNA has the advantages of parallelism,large storage capacity,low consumption,etc.,and combined the two advantages,thus opening a new door to image protection.The thesis studies an algorithm that combines chaotic system and DNA coding to encrypt color images.The main contents are as follows:(1)Analyzing and studying an image encryption combining chaos system,that is chaos mapping and DNA encoding,which find that the key sensitivity of the Chen chaos system used in the algorithm is small,chaotic characteristic is not obvious,and the attractor field covered by orbital speed is slow,the problem of insufficient ability against the attack,this thesis proposed in the initial stage with a new chaotic system to replace the original Chen chaotic map,the map is larger than that of the original Chen chaotic system has more obvious advantage.Firstly,the pixel information of the color image is analyzed to determine the initial state value of the new four-dimensional chaotic system and logistic chaotic map,that is,the key.Secondly,after repeated logistic chaos system,transform to get a matrix of the same size as the original image.Logistic chaos system and then transforming.Finally,we divide the color image and the generated matrix into sub-blocks of the same size,and then four groups of random sequences are obtained according to the initial state values of the new chaotic system.(2)In the image encryption algorithm,the problem of DNA coding operation rule is single,the key distribution is discrete and the algorithm complexity is low.This thesis adds an operation rule for DNA coding operation rule,that is,XNOR operation of DNA.Through the random sequence matrix generated above,and according to the four groups of random sequences obtained by solving the new chaotic system as a reference,the DNA coding method of each sub-block of the input image and matrix as well as the operation method of each other are determined.(3)To determine whether an image encryption algorithm has good security,it is necessary to verify the image encryption scheme.Firstly,it evaluates from subjective simulation results;secondly,it conducts a security evaluation of the algorithm through six objective indicators;finally,the simulation experiment verifies that the image encryption algorithm in this paper has good security.