Abstract: This paper presents a communication protocol of streaming media to ensure secure live transferring of scalable quality video programs over network.In the protocol，client，authentication server and video server collaborate for authentication，generation of session keys and transferring of encrypted streaming media.Bi-direction authentication is carried out by bi-direction challenge method and method based on public-key cryptography.Perfect forward secrecy is provided by adoption of Diffie-Hellman key exchange steps.

Key words: multimedia security, perfect forward secrecy, authentication, scalable streaming media

摘要： 设计面向可伸缩媒体流的安全通信协议以保证可伸缩流媒体服务系统能够为相同的节目源设计不同质量等级的输出码流并确保安全传输。通信协议由客户端、认证服务器和视频服务器3个实体的交互完成，通过基于Diffie-Hellman算法的密钥交换和基于证书机制的双向认证确保产生的临时会话密钥的机密性和通信过程的PFS特性。通过采用CBC模式的对称加密算法、ID与随机数的串接以及用临时密钥加密密钥协商消息等安全机制来确保增强的安全性以抵抗反射攻击和中间人攻击。

关键词: 多媒体安全, 完美前向保密, 身份认证, 可伸缩流媒体