| With the development of multimedia and network technology, the application scope of multimedia video is expanding to almost every walk of life such as economy, military affairs, politics, education and so on. The demand for secrecy and security in the sensitive situations such as politics, economy, military affairs and so on has accelerated the research of video information encryption algorithm. Video information has the characteristics of great data quantity, special code structure, and synchronic transmission. These characteristics set a new request on the existing encryption algorithm, demanding that video information can satisfy the application request such as timeliness, the maintenance of compression ratio stable and the maintenance of data format constant in various degrees while its security was guaranteed.The thesis introduces the history, present situation and the prospect about the video compresses encode and the study of cryptography. It also analyzes the H.264 video compression encoding standard and its'encoding feature, studying the video encryption algorithms that appear in latest decade, and making the summary and the performance analysis according to the kind. On this foundation, the thesis brings forward a kind of new selective encryption algorithm to which the chaos encryption thought has been introduced. The algorithm uses the password sequence which comes from the pseudo-random sequence produced by the chaos mapping, simultaneously bringing forward a kind of key assignment scheme to strengthen the fault-tolerant of encryption algorithm. The result of realization shows that the encryption algorithm which this thesis brings forward has the characteristic of low computational complexity, tight security and synchronic transmission, resulting in weak side effect on compression encode. It is to find wide application. So, the algorithm of this thesis satisfies the elementary request of video encryption better. |
