Research On Technology Of Separable Reversible Watermarking In Encrypted 2D Engineering Graphics

In recent years,as cloud computing capabilities have increased,users can significantly reduce costs by storing,distributing,and processing data in the cloud.Cloud storage applications for multimedia files are becoming more popular,such as images,video,and 2D engineering graphics.However,the files stored in the cloud are out of the user's control,raising concerns about file security and privacy leaks.In order to protect the privacy of users,encryption technology has been widely used.By using secure encryption technology,it is ensured that the cloud service provider cannot obtain the contents of the file without knowing the key.The cloud adds some additional information to the encrypted digital content in a reversible way,such as annotation information,copyright information,etc.,and the cloud service provider can manage these encrypted files well and use this information to determine the owner or integrity of the content.To solve this problem,the reversible watermarking in encrypted domain technology came into being.The technology first encrypts the carrier to ensure the security of the data,and then embeds the secret information into the carrier through the reversible watermarking technology to realize functions such as copyright protection and secret information transmission.At present,most research on reversible watermarking in encryption domain mainly focuses on carriers with large redundancy such as raster images.There are few studies on carriers with poor data correlation such as 2D engineering graphics.However,2D engineering graphics as an important manufacturing data are in the cloud.The safe storage and management has become an important issue that needs to be solved.In addition,most reversible watermarking in encryption domain algorithms can only extract watermarks in a single domain.More importantly,most of the existing reversible watermarking in encryption domain algorithms are not robust.Namely,the watermark cannot be correctly extracted after a certain degree of modification to the released carrier,so they cannot be applied to some scenarios such as copyright authentication or source traceability.Therefore,it has important application value for the research of 2D engineering graphics reversible watermarking in encryption domain technology.To this end,this paper proposes two separable reversible watermarking in encrypted 2D vector graphics algorithms.The main work of the thesis includes:(1)A separable robust reversible watermarking in encrypted 2D vector graphics scheme is proposed.In order to improve the robustness,the algorithm proposes a novel watermark mapping method by combining coordinate system conversion,key hash message authentication code(HMAC)and erasure coding.By extracting the geometric invariant features and using hash collision to generate watermark redundancy,the robustness of the reversible watermark is enhanced.At the same time,in order to control the distortion,a unified distortion control method is established under different parameters.Theoretical analysis and experiments show that the proposed algorithm is not only reversible but also has good invisibility.Compared with similar algorithms,the algorithm has good robustness against common operations(such as RST transformation),and malicious attacks(such as entities reordering,vertex increase and vertex deletion).Moreover,to the best of our knowledge,it is the first work that can robustly extract hidden data both in the plaintext and ciphertext domains.(2)A separable reversible watermark framework in encrypted 2D vector graphics based on integer translation-extension model is proposed.In order to improve the universality of the algorithm,the encryption algorithm in the framework can arbitrarily select the existing vector encryption algorithm based on vertex perceptual encryption.The watermark embedder can perform watermark embedding based on the integer translation-extension model and implement a separable reversible watermarking framework in encrypted domain.In order to control the distortion,a reversible watermarking in encrypted 2D vector graphics algorithm based on histogram translation is proposed.The algorithm enables the distortion of the carrier to reach the lower bound of the model while the capacity reaches the upper bound of the model.Theoretical analysis and experiments show that the proposed algorithm is not only separable but also universal.Compared with similar algorithms,the algorithm has some advantages in terms of reversibility,invisibility and capacity.In addition,the algorithm is robust enough to withstand rotation,translation,and scaling(RST)attacks.(3)Based on Teigha secondary development platform and Microsoft Foundation Class Library,Visual Studio 2015 is used as an integrated development environment to design and implement a reversible watermarking in encrypted 2D vector graphics system.The research results of this paper can be applied to 2D engineering graphics privacy protection and ciphertext data management in cloud manufacturing environment,as well as other privacy protection applications.