Research On Reversible Data Hiding Algorithm In JPEG Image Encryption Domain Based On Histogram Shifting

With the rapid rise of the Internet and cloud storage technologies,the privacy protection of cloud digital images has attracted widespread attention from researchers.However,JPEG format images are widely used in the Internet field through the advantages of small storage files and low transmission time consumption.Therefore,in the cloud storage environment,the research on the reversible information hiding algorithm in the JPEG image encryption domain is of great significance.Although the existing reversible data hiding algorithm for encrypted JPEG images based on histogram shifting has advantages in embedding capacity,it also has two problems:1)This type of algorithm ignores the impact of the embedding position on the file increment,resulting in a larger file increment after embedding information;2)In the encryption domain reversible information hiding algorithm based on histogram translation,the number of embedding coefficients is limited,which makes it difficult to meet application scenarios that require high embedding capacity.Aiming at the above two problems,this thesis takes the reversible data hiding algorithm for encrypted JPEG images as the research goal,and designs two reversible data hiding algorithms for encrypted JPEG images based on histogram shifting around the embedding capacity and file increment.The main work of this thesis is as follows.A reversible data hiding algorithm for encrypted JPEG images based on continuous zero-point features is designed.The algorithm determines the DCT sub-blocks embedded with secret information based on the frequency selection strategy of unit file increment and the average zero run length block selection strategy,and embeds secret information in sub-blocks with less file increments first.In order to reduce the file increment caused by invalid shift,the algorithm divides the DCT sub-blocks into three types: normal block,critical block and abnormal block according to the characteristics of continuous zero points near the peak point,and shift some of the non-zero AC coefficients of the normal block and the critical block.Experimental results show that the algorithm is separable,the embedding capacity can reach more than 1.5 times of the existing similar algorithms,and the increase of file keep small after data embedding.A reversible data hiding algorithm for encrypted JPEG images based on zero AC coefficient is designed.The algorithm first analyzes the file increment caused by the zero coefficient embedding before EOB,and defines the unit file increment function at each frequency.The frequency of the smaller unit file increment is first selected to embed data.And then each embedding sub-block corresponds to The peak point and the zero point of the pair are histogram shifting to embed secret data.Compared with similar algorithms,this algorithm has increased the embedding capacity by more than 0.9 times,and the file increase of file size and unit data increase of file size are both smaller than the existing similar algorithms.In order to visually demonstrate the reversible data hiding algorithm of JPEG image encryption domain based on zero AC coefficient in this article,MATLAB is used to design a simulation system,and users can verify the experimental results through this system.