Studies On Image Data Safety And Reliability Based On Multi-Chaotic Maps

With the increasing market share of the Android operating system,mobile devices are faced with the risk of being controlled by viruses,Trojan horses,adware,backdoors,spyware,etc.In order to ensure the privacy,safety and reliability of the image information stored and transmitted on the mobile devices,the image information needs to be encrypted.The existing image encryption algorithms are mainly implemented for the PC platform,while fewer encryption algorithms for the Android platform.Combining chaos theory and cryptography,an image encryption scheme based on multi-chaotic mapping for Android platform is proposed,which satisfies the requirements of mobile device for high safety,high efficiency and high reliability image encryption algorithm.The main works are as follows.In order to solve the safety problem of digital image on mobile platform,a color image encryption algorithm based on double chaotic map cross-diffusion is proposed.The algorithm generates an initial key by cross-iteration of Logistic and ChebyShev,then determines the parity of the pixel position of the image,and uses the key generated by ChebyShev and Logistic iteration to encrypt the pixel.Then the RGB channels of the pixel points before and after encryption are crossed or diffused to achieve the combination of the ciphertext images.In order to solve the complexity problem of image encryption algorithm performance evaluation,an image encryption algorithm safety evaluation system is developed.The system implements functions of calculation,comprehensive analysis,comparison and Graphical display of various parameters such as histogram,pixel correlation,key sensitivity,key space,NPCR,UACI,information entropy attack,selective plaintext attack and encryption and decryption time of image encryption algorithm,which simplifies the operation process,reduces the error of data statistics and reduces the complexity of algorithm performance evaluation.This system is used to test the algorithm proposed in this chapter.The experimental results show that the algorithm has the advantages of large key space,high safety,small correlation between adjacent pixel points and strong anti-attack ability.With sufficient safety,the encryption and decryption time is reduced and the efficiency is improved by reducing the number of iterations,which is suitable for the encryption of color images on mobile devices such as Android phones and tablet computers with high real-time requirements.With the rapid development of medical informatization and the popularization of digital imaging equipment,a large number of medical images conforming to DICOM standards have been provided for the application of internet telemedicine and medical artificial intelligence.Since the DICOM image not only contains the patient's image information,but also includes the patient's name,age,address,date of examination,hospital information and other personal privacy,the image is with the risk of stealing and tampering in the process of storage and network transmission,which easily leads to moral and social problems.Thus,encryption is required.In order to solve the safety problem of medical images on mobile devices,combined with the characteristics of mobile platform and DICOM image,a multi-chaotic map medical image encryption algorithm was proposed by using Logistic mapping,Chebyshev mapping and improved Cat mapping.The algorithm first analyzes the medical image and distinguishes the color image from the gray image.For gray images,the improved Cat map is used to scramble them according to the optimal number of iterations,and then the diffusion is realized by the double chaotic cross-diffusion algorithm.The color image is encrypted by cross-diffusion algorithm of double chaotic map.Finally,the designed safety analysis platform of medical image encryption algorithm is used to test the algorithm proposed in this chapter.The experimental results show that the algorithm has the characteristics of small neighboring pixels,large key space,strong key sensitivity,high safety and short encryption time.It is suitable for medical image encryption of mobile devices with high real-time requirements.Applying medical image encryption algorithms to mobile devices,a medical image sharing cloud platform based on multi-chaos mapping encryption algorithm is designed.With this platform,doctor-patient users can realize online real-time browsing,sharing and diagnosis of medical images through mobile APP and Web terminal,which further verifies the safety,real-time and reliability performance of the algorithm proposed in this thesis.