A Security System Design And Implement Of Multimedia Communication Based On H.323 Network

The communication of multimedia is a multi-task-oriented system which transfers voice, image, and date file by p2p or peer to multi-peer. The communication of multimedia is mostly based on the Circuit Switching in the past, and with the improvement of the foundation of data operation, the tendency is based on the packet switched data network. However, this network will face large risk during the transfer of multimedia stremas, and many organizations or corporations have done much work on this problem such as ITU.The outside cipher device is based on private network which uses H.320 standard, and it adapts to the IP network. H.320 is a new cryptography which can be applied to the transfer of multimedia streams. Currently, many corporations have achieved to add encrypting modal to special devices, but we still can't encrypt the data in IP network.This thesis proposes a cipher system which implements the security of media streams. There isn't any mutual protocol between the multimedia terminals and the encrypting devices. This system can solve the problem that the embedding cryptography has to depend on the special devices, and can realize the security of media streams among terminals in IP network.The thesis introduces the architecture of that system and it's system design. The system includes Endpoint module, Network module, CipherNego mudule, SysCtrl module and CipherApi module. To combine my work on the system, the thesis describes the realization of the CipherNego module and the SysCtrl module specially, and other moduls' realization are also be introduced. Several most important technologies are used during the realization of that system including the recognition of the media streams packet, the transparent transfer of packages, the identifier of the multimedia communication's ending, the method to pass firewall for the defined protocol packages of cipher system, the realization of the session key agreement of 2-layer devices between subnets.A cipher device has been carried out which according to the system design. The device has been applied in the military or some corporations' multimedia conference, and it has been received good response from marcket.