The Design And Realization Of Encryption System Of Video Stream In Videoconference

With the rapid development of Internet, the market prospect of the application in videoconference is growing widely. As videoconference is often related to sensitive, pivotal data about enterprise or government organization, it needs high encryption intensity. During the practice ofgradutate student, I participated in the development of WITNET-Video?inthe Jiaoda Withub Information Co., Ltd. I am responsible for secure transmission of MPEG- II video stream in the network. I designed and realized the encryption system of MPEG-II video stream in videoconference, whose ercryption intensity achieves the level of market secret. The encrytion system makes full use of structure characteristic of MPEG-II, combined with secure performance demanded in videoconference. A selective encryption scheme of video stream is proposed making compromise of computation quantity and encryption intensity, which makes main emphasis on the study of the key management and uses cipher mechanism mixed by 3DES symmetrical algorithm and RSA unsymmetrical algorithm. Some frames in video stream are encrypted by 3DES private-key algorithm. And keys of 3DES are encrypted by RSA public-key algorithm. Key management provides a set of procedures generation, distribution, storage and deletion, implemented by the technology of certificate and digital signature. The certificate mechanism of X. 509 is introduced to resolve the problems of the RSA public-key distribution and combination of users' authorized identity with the pair of public-key and private-key. The two level structure of this key management system leads to a definite certificate authentication path, which makes the verifying procedure shorter and makes the system easier to be realized.