Security Analysis Of Some Image Privacy Protection Algorithms

With the rapid development of social networks and cloud platforms,privacy protection for sensitive images and videos has received increasing attention.Numerous algorithms have been proposed to protect the privacy of multimedia data.Some algorithms have been proved to be insecure against variety of cryptographic attacks and others require careful analysis for their security evaluation.Good cryptanalysis works are the incentive for researchers to design better privacy protection algorithms,but the according studies of cryptanalysis are remained in underdevelopment.In this work,some privacy-preserving algorithms for sensitive images and videos are introduced,and some typical algorithms of them are selected for security evaluation.The analytical results provide some helpful suggestions for designing the relevant algorithms.The main contributions of this thesis are as follows:? A review of the research works about image or video privacy-preserving in the past twenty years is given.This thesis summarizes and analyzes the schemes that use scrambling method and electrocardiography signal,and finds out some potential security defects of some typical image or video privacy protection schemes.? Based on the position scrambling method,an image encryption algorithm of pixel bits(ISEA)was proposed by G.Ye et al.With the correlation remain in image data,an effective ciphertext-only attack is proposed here to reveal some or all important visual information of the corresponding plain-image.Known/Chosen-plaintext attack is also applied on the algorithm to qualitatively analyze the security capacity of ISEA.? An image encryption algorithm based on image blocks and electrocardiography signal(IEAE)was presented by G.Ye and X.Huang in 2016.This thesis pinpoints the essential structure of IEAE and proposes an effective known-plaintext attack to get the equivalent key of IEAE.Using this algorithm as a typical counterexample,this thesis also summarizes some security defects in the design of IEAE.The lessons are generally applicable to many other image encryption schemes.