Research Of Combination Of Watermarking And Encryption Based On H.264 Standard

With the rapid development and widely application of Internet technology and digital multimedia technology, kinds of video and video services (such as digital television, video on demand, video conferencing and video surveillance, etc.) are increasingly popular and widely used. However, the digital multimedia products have the features such as easy transmission, lossless copy and distribution. These features not only bring convenience to people, but also bring some issues on information security, such as information theft and leakage, the piracy of digital products and data tampering. Therefore, how to protect media data has become an important research subject. To protect video data, two means have been proposed and highlighted since the past years, i.e., video encryption and video watermarking.Video encryption encrypts video data into unintelligible ones before the video be transmitted with ciphers, which protects media content's confidentiality. The encrypted videos are often difficult to be understood. Video encryption protects the security of video content only during transmission; once the data is decrypted it can not provide further protection. The emergence of video watermarking makes up the shortage of video encryption. Video watermarking embeds some information into video data perceptibly or imperceptibly, which protects media data's ownership or identification. For video encryption and video watermarking realize different functionalities, they can be combined together to protect both the confidentiality and the ownership.H.264 is a new generation of video coding standard and efficient compression method, having a broad appliance perspective. Considering the actual appliance of video protection technology, this paper focuses on combination of encryption and watermarking in video compression. The emphatic research work and contribution of this thesis are as follows:(1) This thesis systematically summarizes the characteristics and the application of video encryption and video watermarking, and focuses on the research status of video encryption and video watermarking algorithm and principles. Then, introduce systemically about the basic knowledge of H.264.(2) This paper proposes the Adaptive Activity Quantization Index Modulation (AAQIM) watermarking algorithm based on H.264. In AAQIM, the variation is dispersed over host values of a region. The watermark embedded in I frame only slightly affects the successive P/B frames. Simulation results show that AAQIM guarantees a better performance in transparence. And the proposed method is extremely robust against re-encoding, noise attacks and filter. And it extracts watermark without the original video signal. Additionally, the proposed method is also simple and appropriate for real-time applications.(3) A novel scheme for secure video transmission and distribution, basing on the combination of encryption and watermarking, is proposed in this paper. In H.264 compression, the intra-prediction mode (IPM), motion vector difference (MVD) and DCT coefficients are encrypted, while DCT coefficients'amplitudes are watermarked by Adaptive Activity Quantization Index Modulation (AAQIM) watermarking algorithm. Performance analysis and experimental results show that encryption can exhibit higher security and has little impact on code length and computational complexity. AAQIM guarantees a better performance in transparence. The watermark embedded in I frame only slightly affects the successive P/B frames. The proposed watermarking scheme is extremely robust against re-encoding, noise attacks and filter. Video encryption is independent from video watermarking, thus the watermark can be extracted from the encrypted videos, and the encrypted videos can be watermarked directly. Encryption and watermarking can be employed respectively for appropriate situation or be combined together to protect both the confidentiality and the copyright, so this scheme is of practical use.