为保障H.323系统视频通信的安全，需要在H．323框架内使用ITU-T的H．235协议所提供的安全业务。文章首先描述了H．235协议所涉及到的身份认证、数据完整性、媒体流加密、不可否认性等方面的安全服务，然后按照一个视频通信连接建立的顺序讲述H.235协议在各个环节所建议的安全措施，其中着重论述了在H.235框架下提出的身份认证和媒体流加密部分所采取的方案,分别是基于Guillou-Quisquater算法的身份认证方案和基于伪随机序列将宏块置乱的媒体流加密方案，最后介绍了H.235系统中的密钥管理部分。关键字：H.235；身份认证；媒体流加密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, People’s Liberation Army 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