Video Encryption Algorithm And Engineering

With the development of Internet and video compression technology, video applications such as video conference and video phone become more and more popular. Meanwhile, when the contents of video concern national secret or personal privacy, they may need to be transmitted with the protection of encryption. Differing from text-data, video data is enormous and often processed in real-time. Therefore, traditional encrypt algorithms are not appropriate for video-data.In this dissertation, H.263 video compression standard is first reviewed, and then a code simplified, interface encapsulated and function improved version of H.263 codec is also introduced. After some existing video encryption algorithms being summarized, one enhanced video encryption method using spatio-temporal chaos has been put forth. Furthermore, two secure video conference systems have been constructed, namely Peer to Peer secure conference system and Multicast secure video conference system, in which three optional chaos based encryption algorithms are integrated. Both above mentioned systems have the function of capturing and displaying video locally, compression, encryption and transmitting video on LAN in real-time.Moreover, a wavelet-based video coding scheme, VWC for short, is also attempted. Instead of dividing one frame into several blocks and using block-based DCT that often appears in traditional video codec standards, VWC imposes wavelet transform (WT) on whole frame and encodes the wavelet coefficients, thus, some superior performances like accurate bit-rate control, low CPU overload, and high error-resistance are achieved at the expense of low compression efficiency. Combining with VWC, a chaos-based video stream encryption algorithm has been proposed which has the ability of deciphering video stream with arbitrary bit-length and grading security control. Due to the interleaving of plaintext and cipher-text, new algorithm could resist several attacks like known-plaintext attack and chosen-plaintext attack. Experimental results have demonstrated all above good features of the algorithm.