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