Research On Medical Image Encryption Algorithm For Cloud PACS System

Digital hospitals have become the trend of modern medical care.Picture Archiving and Communication Systems(PACS)is an important hardware support for digital hospitals.The PACS system is mainly oriented to the field of medical image processing.Medical images are not only large in data volume but also extremely demanding on confidentiality.With the development of cloud computing,cloud computing centers have solved the problem of data storage,and improving the performance of image encryption has become a problem that cloud PACS systems need to solve.Due to the difference between the image imaging principle and the actual pathological diagnosis requirements in the cloud PACS system,grayscale images and color images of different pixels are formed,and how to encrypt these images becomes one of the difficulties.In order to improve the effectiveness of digital image encryption and enhance the adaptive ability of image encryption,this paper designs the overall framework of image fast encryption based on wavelet transform,chaos theory,s-box,genetic algorithm and other theories and algorithms,and proposes targeted encryption methods.Firstly,the paper proposes a fast encryption method based on lifting wavelet optimization for high-pixel gray-scale images formed by DR and other devices in cloud PACS system.The threshold method is improved by the combination of soft threshold method and hard threshold method.The problem of lifting wavelet update operator is solved.On the basis of dynamic inertia weight,a non-equilibrium mutation strategy is proposed to randomly adjust the optimal particle position.The improved particle swarm optimization algorithm solves the problem of lifting the wavelet linear prediction operator.By optimizing the update operator and linear predictor of lifting wavelet,the fast decomposition ability of lifting wavelet is improved,and the wavelet low-frequency coefficient obtained by adaptive wavelet decomposition of digital image has good sparsity.Furthermore,the image low-frequency coefficient encryption scrambling mode is designed,and the chaotic system's initial value sensitivity and parameter sensitivity are fully utilized.Two chaotic sequences are selected to perform gray value encryption and position scrambling on the low-frequency coefficients of the image,and the encryption system key space is expanded accordingly.Secondly,the paper proposes a digital image adaptive encryption method based on empirical mode decomposition for low-pixel gray-scale images formed by CT and MR devices in cloud PACS system.According to the characteristics of the image itself,after the image is decomposed by the empirical mode,the component with the least distortion of the image is selected for encryption,and then the image is reconstructed.The EMD algorithm is used to decompose the digital image,which destroys the correlation between adjacent pixels and plays a good encryption effect.In the image encryption process,an image adaptive encryption method based on key sequence guidance is adopted.Introduce the user key,use the secure hash algorithm to obtain the fixed-length key sequence,based on the encryption idea of one-time-one secret,adaptively transform the encryption key and dynamically construct the encryption scrambling mode,loop-guide pixel gray value encryption and pixel position Scrambling and improving the fast encryption ability of digital images.Thirdly,the paper proposes a genetic image based on genetic and chaotic digital image encryption algorithm for high-pixel color images formed by B-ultrasound and gastrointestinal endoscopy in cloud PACS system.The paper introduces the hyperchaotic system in the process of digital image scrambling,so that the image scrambling result depends not only on the chaotic sequence generated by the initial key,but also on the characteristics of the image itself,so that it has certain adaptive features,through the introduction of inheritance.The algorithm performs dynamic optimization of parameters of the image encryption and decryption process to obtain an optimal encryption and decryption process and steps.In the encryption process,a clear feedback mechanism is introduced to improve the sensitivity and resistance to plaintext,improve the encryption efficiency,and solve the problem that the high-dimensional chaotic encryption takes too long and the efficiency is low when the encrypted image is attacked by plaintext and ciphertext is selected.Finally,the paper proposes an image encryption algorithm based on Kelly diagram and swapping S-box structure for low-pixel color images formed by B-ultrasound and gastrointestinal mirror in cloud PACS system.Based on the standard algorithm of S-box image scrambling,a scrambling encryption algorithm based on Kelley diagram and swapping S-box image is proposed.Chen chaos theory is introduced to generate chaotic random sequence.After testing and analysis,the paper is constructed.The S-box's bijectivity,nonlinearity,strict avalanche criterion,and uniformity of difference can satisfy the security of the cryptographic algorithm.Through experimental analysis,the low-pixel color image fast encryption in the PACS system can be realized based on the Kelley low-pixel color image and the swapped S-box structure image encryption algorithm.