Encryption Algorithm For Format Compliance Of Video Based On Coupled Map Lattice

With rapid development of Internet and digital technology, video data are used widely, such as video on demand, paying TV program, video conferences and so on. All of these applications have different demands for the security of video data. The difference between the video applications and the ordinary computer applications is the vast amount of data generated by video applications and the real-time constraints required for the video applications. Traditional cryptographic algorithms for data encryption such as DES are not fast enough to process the vast amount of data generated by the video applications, so new algorithms are needed. Meanwhile, there is no need to encrypt the whole video in some applications, such us video on demand, in which users could make decision whether to pay for the high-definition video according to some viewdata of lossy video. So selective encryption as a new algorithm is studied by more and more researchers. Moreover, a proper selective encryption algorithm can effectively control the amount of data generated by encrypting, and it's very important for mobile terminal with poor processing ability and some network applications in which network bandwidth is very expensive.Recent years, with requirements for different commercial applications, a new concept-- format compliance appears. It wouldn't change the syntax of video data after been encrypted, and make the encrypted video data can be played in media player with no error. The contents to be played are different as the different demand for safety of video data.On the promise of the safety for MPEG video data and effective control of compression ratio, several basic techniques for MPEG-compliant selective encryption algorithm based on the characteristics of encoding MPEG were proposed in this paper. Some of the contents of this paper are listed as follows.First, we have a review on present selective encryption algorithms and encryption algorithms for format compliance and analyze their characteristics, then propose what we should to solve.Secondly, we make a brief introduction on Chaos theory and the model of Coupled Map Lattice (CML), then propose the encryption model for this paper based on two skew tent map.Thirdly, we make a brief introduction on MPEG compression coding standard, and propose MPEG-compliant selective encryption algorithms on DC coefficient, AC coefficient and motion vector respectively based on the characteristics of coding. The experiment results and the compression ratio analyses were presented.Fourthly, we analyze the safety of the encryption algorithms proposed in this paper based on stream cipher and selective encryption algorithm individually. Then, according to the demand on effective control of compression ratio and safety, we propose an improved algorithm. The experiment results and the compression ratio analyses were presented too.Finally, the dissertation is concluded. Some problems as well as further work are also given.