Investigation On High Capacity Reversible Data Hiding In Encrypted Images

The rapid development of big data and cloud computing makes it easy for people to upload massive amounts of information to cloud servers for storage,or use its powerful computing power to serve themselves.At the same time,it also brings people many information security issues.Reversible data hiding is one technique that can conceal secret data in the ciphertext carrier under the premise of ensuring the content of the hidden carrier,which can effectively protect the security issues in the ciphertext transmission process,and at the same time,it is convenient for cloud managers to manage massive amounts of information.Therefore,the study of reversible data hiding algorithms in the ciphertext domain is a hot spot in the field of cryptography in recent years.The vacating room after encryption(VRAE)algorithm has high security,however,the encryption will reduce the redundancy of the pixels,the effective load is low and it cannot ensure the error-free extraction of data and recovery of the image.The reserving room before encryption(RRBE)algorithm can make full use of the correlation between pixels to obtain a satisfactory payload,but the security is low.In response to the above problems,this paper proposes two improved reversible data hiding methods.Under the premise of achieving higher security,they ensure that they achieve higher capacity payloads.The overall performance is better than the existing similar algorithms,which satisfies people's requirements for different application scenarios.1)Propose a separable reversible data hiding algorithm in encrypted images based on improved fixed-length run-length coding.First,the original image is encrypted using multi-step scrambling(scrambling of bit planes,blocks,and block pixels),and then the lower bit planes are compressed using an improved fixed-length run coding method,so as to obtain a space that can accommodate secret information.The receiver can either extract the secret data independently or restore the original image separately as needed.It can be seen from the experimental results that the average embedding rate of the algorithm in this chapter can reach 1.2522 bpp.On the receiving side,the original image can be restored100%,and the separation operation of restoration and extraction is realized,which has strong practicability.2)Propose a reversible data hiding algorithm in encrypted images using pixel rearrangement and classification coding.The algorithm contains 16 pixel rearrangement methods,each of which aims to combine the highly similar bits of each high bit plane by rearranging each high bit plane.For each high bit plane,the plane is rearranged in a manner with the best aggregation performance from the pixel rearrangement,and then the rearranged bit plane is compressed in a group-by-group manner by classification coding.Classification coding can compress not only a single group with a bit value equal to 1(or 0),but also several consecutive groups.In the experiment,the highest embedding rate of an image of size 512×512 is 2.3704 bpp.At the same time,stream cipher encryption and scrambling operations improve the security of the encryption method.Experimental results show that this scheme can achieve larger embedding capacity and higher security.