Research On Commutative Encryption And Watermarking Algorithm In Ciphertext Domain Based On Image Features

With the rapid development of the Internet era,network multimedia information is vulnerable to malicious attacks by illegal acts such as theft and piracy in the process of storage,transmission and use.Therefore,the security protection of network multimedia information,on the one hand,requires active encryption protection of multimedia information from infringement in the process of storage and transmission;on the other hand,it requires copyright identification and source traceability of multimedia information.Therefore,the effective combination of cryptographic technology and digital watermarking technology can not only achieve the security protection of multimedia information,but also achieve the copyright tracking of information in the process of use.However,the direct combination of cryptographic technology and digital watermarking technology has some problems,such as complex operation sequence,low security and so on.Commutative encryption and watermarking organically combines cryptographic technology with digital watermarking technology,and has the characteristics that the order of encryption and watermark embedding,decryption and watermark extraction can be exchanged,that is,the watermark can be extracted directly in ciphertext or after decryption,which overcomes the problems and shortcomings caused by the direct combination of cryptography and watermarking technology.In this thesis,the commutative encryption and watermarking theory and algorithm of image data features are studied.The main work and achievements are as follows:1.This thesis expounds the security problems and requirements encountered in the practical application of image data,summarizes the common characteristics of image data,and analyzes the common combination methods of encryption and watermarking.On this basis,the construction form based on image invariant features is studied to establish a theoretical basis for the implementation of commutative encryption and watermarking scheme.2.In order to solve the problem of complex operation order of encryption and watermarking,combined with the histogram characteristics of image data,a commutative encryption and watermarking scheme based on histogram invariant is designed.Making use of the invariant histogram of the image before and after permutation,the algorithm maps the operation of embedding watermark in ciphertext to plaintext,and realizes the exchange of encryption and watermark operation sequence.When extracting the watermark,the watermark can be extracted directly from the ciphertext containing the watermark,or the watermark can be extracted after decryption.The experimental results show that at the extraction end,the image quality of plaintext with watermark is higher,and the invisibility of watermark is good.3.In view of the lack of robustness of commutative encryption and watermarking algorithm,combined with the singular value characteristics of the image,a commutative encryption and watermarking scheme based on Zuchongzhi cryptographic algorithm and discrete wavelet transform-singular value decomposition is designed.Based on the characteristic of singular value invariance,the watermark is embedded into the singular value,and the singular value matrix set and singular matrix set are permuted and encrypted by ZUC algorithm.Watermark embedding operation and encryption operation do not affect each other.,and the complete watermark can be extracted from both watermarked ciphertext and decrypted plaintext.The experimental results show that the invisibility of the watermark is good,and the algorithm has high security and robustness.4.Taking advantage of Sphere-Hardening dither modulation watermarking algorithm,combined with ZUC algorithm and Arnold permutation encryption algorithm,a commutative encryption and watermarking scheme is proposed.After preprocessing the original data,the SHDM watermarking algorithm is used to embed the watermark information,the ZUC cryptographic algorithm is used to encrypt the symbol bit stream of the data,and the Arnold algorithm is used to encrypt the position of the data.The experimental results show that the scheme realizes the interchangeability between the cryptographic algorithm and the watermarking algorithm,the encryption effect is good,and the watermark information can be extracted successfully in both the ciphertext domain and the plaintext domain.