Study On Key Technologies Of Secure Video Watermarking And Their Applications

Watermarking is often regarded as an important technique in the research field of information security. In recent years, watermarking security has emerged as a new subject in the watermarking area. And it brings new challenges to the design of watermarking systems.This dissertation focuses on some key problems related to watermarking security. At the same time, the contrast between watermarking security and cryptography and the analytical framework of watermarking security are discussed. On these foundations, the dissertation accomplished some main works and efforts.First of all, the mathematical model of linear collusion attack is given. And according to the model, the design rules of video watermarking for resistance to linear collusion are put forward. Moreover, adaptive video watermarking algorithms are proposed, which are effective resistance to linear collusion in spatial domain. The proposed watermarking algorithms can not only be robust enough to cropping, frame removal, frame insertion, frame reorganization, imperceptible geometrical distortion and linear collusion, but also reduce the impact of compression under some conditions.The property of robustness and security should be both considered in designing of multimedia-hashing algorithm. In particular, the security issue is very important in applications. Based on the 3-D Discrete Wavelet Transform (3D-DWT), a novel scheme of computing a robust hashing from video clips is proposed. The research of multimedia-hashing security is still at the initial stage. Till now, there are only few literatures for it, which just focus on the experimental side of estimating the unicity distance for image hashing. A theoretical framework is proposed for the security analysis of multimedia-hashing based on a cryptanalysis point of view (Shannon's mutual information), in which the unicity distance is used to measure the security level of hashing. At the same time, the problem of one-way proof about the proposed hashing scheme is solved. These have laid a good theoretical basis for our further study of multimedia-hashing security.Next, in the application of copyright protection, we consider two problems: one is that an adversary edits a watermark to embed the work and claims that he is owner of the work; the other one is that the adversary finds a legal watermark and embeds it to his work (copy attack). In order to solve the above problems, a secure and robust video watermarking method for copyright protection is proposed. In this method, firstly, a robust hash was computed from video clips based on the 3D-DWT and median quantization, and then video hashing (secret key based) was gained. Secondly, the short hash using the proposed algorithm is used to create the embedding watermark. The proposed algorithm can not only be useful in the proof of ownership of video clips, but also be used for resisting the copy attack.Considering the possibility of fraud and the immediacy of extract process in the application of broadcast monitoring, a secure video watermarking scheme for broadcast monitoring is put forward in special domain based on the communication diversity technique. In the proposed scheme, the generated hash and copyright information are combined to create the embedding watermark for the authentication of the video clips. Moreover, the quantitative analysis of the proposed algorithm security is carried out using the proposed framework in chapter 3 and the existing framework.Finally, a video watermarking protocol for broadcast monitoring is proposed. In broadcast monitoring, an advertiser wants to inserts a unique watermark into the advertisement before sending to the broadcast station. In view of the fraud between advertiser and broadcast station, authentication of a video clip and an embedding watermark find application in the detected process of broadcast monitoring. To avoid the problem of double authentication, generation and embedding of watermark are based on the homomorphic public key cryptosystems in the proposed protocol. Furthermore, the watermark, the advertisement and the transaction are bound according to the embedding of a unique watermark. It can not only deal with the customer's right problem and unbinding problem, but also avoid the fraud between advertiser and broadcast station.