Research And Design Of Data Hiding Algorithm In Encrypted Image Domain

With the rapid development of information technology, communications with each other become more convenient. In order to avoid the malicious disclosure of user’s personal privacy, information security technology has been widely used. Digital image contains a large amount of information, which is a very intuitive information carrier. For the purpose of guaranteeing the privacy of image content, image encryption is an effective technology. Meanwhile, the image data hiding technology can effectively protect the copyright of digital works. Combining the two methods together and applying data hiding in the image encryption domain can realize the confidentiality and privacy of the image, and also achieve invisibility of confidential information. Data hiding techniques in image encryption domain have been a popular research field in recent years.Based on the existing related algorithms, this thesis puts forward new algorithms and schemes. The main contents are as follows:①By studying typical algorithms of image encryption and image data hiding, the homomorphic encryption and LSB modification and replacement algorithm are selected as the basic method in this thesis. Then, by analyzing the existing three kinds of data hiding schemes in the image encryption domain, an idea, to construct a space where there is no space, is proposed and used to further the following study.②This thesis adopts a LSB rotation method, which makes each block can carry 2 bits of additional data. The experimental results are compared with Zhang and Hong’s schemes. Then, by combining the LSB flipping and LSB rotation methods together, a scheme that each block can carry 4 bits is proposed. The larger the block size is, the lower the error rate is. The experimental results demonstrate that the error rate of the proposed method is much lower than Zhang’s and Hong’s schemes under the same embedding capacity.③Based on the properties of high precision in singular value decomposition, this thesis proposes a scheme of reversible data hiding in image encryption domain for the security applications of cloud computing. The scheme can make full use of the LSB planes in image ciphertext for data hiding. The embedding capacity is much higher than that of the existing reversible data hiding in image encryption domain schemes. When the embedding rate is more than 0.5, our scheme can maintain a higher PSNR than other schemes. Since extraction of embedded data and image restoration are separable in this work, it has practical application value.Finally, the conclusions of this thesis are given, and the future work is also illustrated.