為保障H.323系統視頻通信的安全，需要在H．323框架內使用ITU-T的H．235協議所提供的安全業務。文章首先描述了H．235協議所涉及到的身份認證、數據完整性、媒體流加密、不可否認性等方面的安全服務，然后按照一個視頻通信連接建立的順序講述H.235協議在各個環節所建議的安全措施，其中著重論述了在H.235框架下提出的身份認證和媒體流加密部分所采取的方案,分別是基于Guillou-Quisquater算法的身份認證方案和基于偽隨機序列將宏塊置亂的媒體流加密方案，最后介紹了H.235系統中的密鑰管理部分。
關鍵字：H.235；身份認證；媒體流加密

One Kind of Secure Video Transportation Scheme Based on H.235 Recommendation WANGBin1 XU Zhengquan1 GUO Guangxin2 （1Multimedia Communication Center, National Laboratory for Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University,129 Luoyu Road,Wuhan,China,430079） (2Communication Section of 71799 Unit, *** of China) Abstract：In order to ensure the security of multimedia communication of H．323 system，Recommendation H．235，produced by ITU-T，should be used within the framework of the H．323 to incorporate security services．The paper first describes the main security services referred by Recommendation H.235,such as authentication, integrity, media stream privacy and Non-Repudiation, then illuminates all the security measures advised by H.235 in all the steps according to the sequence of video transportation connection, including the authentication scheme based on Guillou-Quisquater algorithm and the media stream encryption approach based on macroblock permutation using Pseudo-random Sequence . In the end , the part of key management in the H.235 system is introduced.
Key words：H.235； authentication； media stream privacy