Research On Image Encryption And Data Hiding Algorithm Based On Chaotic Systems

With the development of computer technology,the security of digital image information transmission is getting more and more attention,and encrypting or hiding the image information is one of the effective ways to ensure the secure transmission of confidential images.Compared with text,image has the characteristics of large amount of information and high data redundancy,and the traditional encryption algorithm based on text data is no longer suitable for image.Scholars have found that chaotic systems with high initial value sensitivity,intrinsic randomness and ergodicity have many common features with cryptography and are suitable for image encryption and data hiding.The thesis focuses on chaotic systems and combines other relevant theories to design an image encryption scheme while improving an information hiding encryption algorithm.The specific work is as follows:(1)A two-dimensional chaotic mapping is designed,which has the advantages of simple structure and fast iteration,and thus an image encryption algorithm based on the combination of DNA novel operations and S-box for this mapping is designed.The algorithm uses the chaotic mapping to generate a random matrix and an S-box,then replaces the random matrix with the S-box,and finally performs DNA operations on the replaced matrix and the plain image.The experimental data show that the algorithm has better security and certain advantages over other algorithms in the literatures.(2)A four-dimensional conservative chaotic system with good stability and good ergodicity is designed and innovatively applied to an existing reversible data hiding image encryption algorithm to achieve improvements.First,the key and the random sequence generated by the chaotic system are used in the encryption and data embedding stages to improve the security of the key and data,and then the data embedding rules are improved to propose a new ”L” embedding pattern.The experimental data show that the improvement of the algorithm increases the embedding capacity of the data,and the security and resistance of the algorithm are enhanced.(3)The GUI simulation systems of two encryption algorithms are designed.The simulation systems can clearly present the key data in the process of encryption algorithm,which helps to understand the encryption process of the algorithm,and the simulation systems is portable,which effectively improves the practicality of the designed algorithm and has certain practical application value.In addition,because the traditional image encryption algorithm generates encrypted images without visual meaning and the image transmission is poor,at the end of this thesis also designs a scheme to hide the encrypted images without visual meaning for transmission,in order to further improve the algorithm system and meet the actual transmission requirements.The encryption algorithm designed and improved in the thesis has certain advantages compared with existing algorithms,and it further ensures the security of the encryption system while improving the performance advantages of the algorithm.In addition,the designed algorithm GUI systems and image hiding scheme also have corresponding practical application value and certain research significance.