Research On Reversible Data Hiding Algorithm Of JPEG Encrypted Image Based On Rotation Run-length Coding Pair

Reversible Data Hiding in Encrypted Image（RDH-EI）is an emerging technology that combines encryption and reversible information hiding.It can realize reversible information hiding in ciphertext images while protecting information security from two aspects and is very suitable for scenarios with high security requirements such as cloud storage.Because JPEG images have a higher compression ratio and better visual quality,and are most widely transmitted and stored on the Internet,this thesis will take the JEPG image RDH-EI algorithm as the research object to ensure JPEG format compatibility,encryption algorithm security and under the premise that the RDH-EI algorithm is completely reversible,with the goal of improving the embedding capacity and ensuring the growth of no code stream,a JPEG image RDH algorithm and a JPEG image encryption algorithm are proposed.The main research work is as follows:First,studying the existing typical RDH algorithm for JPEG images,analyzing their advantages and disadvantages,and find that most of the existing RDH algorithms for JPEG images have one or more of the following problems:low embedding capacity,serious code stream growth,complete extraction of information cannot be guaranteed,and the original image cannot be completely restored.In response to these problems,this thesis proposes a RDH algorithm for JPEG images based on rotating run-length coding pairs,classifying DCT blocks three times,the run-length encodings in the specified DCT blocks are rotated to hide information.In order to verify the feasibility of the algorithm in this thesis,a series of experimental verifications are designed.The experimental results show that compared with the existing RDH algorithm for JPEG images,the algorithm proposed in this thesis has no code stream growth,complete information extraction,lossless restoration of the original image and the higher embedding capacity,compared with the similar algorithm He^[65],the embedding capacity is increased by about 150%.Then,in order to make the RDH algorithm proposed in this thesis can be applied to ciphertext JPEG images,the typical existing JPEG image encryption algorithm is studied,and its advantages and disadvantages are analyzed.The existing JPEG image encryption algorithm has one or more of the following problems:poor format compatibility,serious code stream growth,poor attack security,the need for secondary entropy encoding,and the destruction of the AC coefficient run and amplitude distribution characteristics in the DCT block（Encryption leaves no room for hiding）.In view of the above problems,based on the encryption algorithm of He^[61]in 2018,this thesis proposes a new JPEG image encryption algorithm that maintains the distribution characteristics of AC coefficients and performs experimental simulation verification.The experimental results show that the new encryption algorithm has good format compatibility,the ciphertext image has no code stream growth,high attack security,no secondary entropy coding,retains the AC coefficient distribution characteristics,and can be perfectly combined with the proposed JPEG image RDH algorithm.Finally,in order to verify the feasibility and effectiveness of the algorithm in this thesis,the JPEG image RDH-EI framework combining the encryption algorithm and RDH algorithm in this thesis was selected.A GUI simulation system was designed to visually demonstrate and verify the performance of the algorithm.At the same time,analyze and summarize the algorithm proposed in this thesis,point out its shortcomings and point out the direction of the next research work.