【摘要】 分析了基于IP的视频会议所面临的安全威胁及其安全需求。通过扩展SIP协议，设计和实现了一种视频会议的安全机制。与会者在加入会议过程中，利用证书向MCU进行身份认证，同时与MCU完成了密钥协商，用于对会议中经多播传送的媒体流进行加解密。此机制还对部分信令消息进行了加密和签名，保证了视频会议参加者身份的真实性以及通信数据的完整性和机密性。更多还原

【Abstract】 The paper analyses the security threats and requirements of video conference. It also designs and implements a security mechanism of video conference by extending the session initiation protocol. Participants use their certificates to authenticate themselves to MCU, and negotiate keys with MCU. The keys are used for the encryption/decryption and authentication of media streams transferred by multicast in the conference. Some signaling messages are also encrypted and signed by this mechanism. This security mechanism supplies authentication for participants, integrity and confidentiality of communication data.更多还原