The Security Research Of Reversible Data Hiding Alogorithms In Encrypted Images

Reversible data hiding in encrypted domain is a technology for reversibly hiding information in encrypted digital images.It has both the advantages of encryption technology and reversible information hiding.It not only protects the contents of digital images,but also closely monitors the propagation and content tampering of digital images,thus it can be widely used in medical,military,cloud storage,legal authentication and other fields.As a technology in the field of information security,its security is one of the core indexes of the performance evaluation.But at present,there are few concerns about algorithm safety in the process of design and performance evaluation.And most of known algorithms are encrypted simply by XOR or scrambling,which is not secure enough.In this thesis we focus on the security of reversible information hiding algorithm in encrypted domain.We analyze the security of a typical algorithm,point out the security vulnerabilities of the algorithm,and then put forward the improvement plan.We design a new secure reversible information hiding algorithm in encrypted domain.The main research work of this thesis is as follows:From the perspective of the security analysis of modern cryptography,we analyze the security of an encrypted domain reversible information hiding algorithm based on compressive sensing and discrete wavelet transform.Using chosen-plaintext attacks and differential cryptanalysis,we find the security flaw and easily extract all the encryption keys and all the embedding keys by merely 14 spatial images.On this basis,two improved suggestions are put forward:First,in order to overcome the security defects of the Arnold global scrambling in the original algorithm,such as periodicity,the chaotic sequence is used to obtain random index matrix for global scrambling.Second,low-frequency encryption key stream is related to the plain-image,the watermark image and the key.Therefore,the improved algorithm can resist the above attacks and achieve higher security.A secure reversible information hiding algorithm in encrypted images based on Modular Addition is proposed.First,we encrypt the plain-image based on Modular Addition in space domain and obtain the corresponding cipher-image.Because the keystream in encryption process is related to the cipher-image,this design can resist chosen-plaintext attacks and differential cryptanalysis.Then we block the cipher-image,keep the middle pixel value of each block unchanged and change the values of other pixels in the block,so as to realize data hiding.The simulation shows that compared with other block based algorithms,the algorithm achieves a lower bit error rate when the embedded capacity is invariant.