MBMS移动多媒体广播/组播业务,基于广播业务的一对多的特性,为了保证数据传输过程的保密性,流媒体传输过程的安全问题已受到普遍关注。一个具有安全保护功能的RTP协议即SRTP协议系统的实现不仅有利于对抗网络安全攻击,而且能够为用户提供隐私、加密和认证保护。因此,MBMS中的解密算法的研究就显得非常重要。 MBMS mobile multimedia broadcast / multicast service, based on the one to many features of broadcast services, in order to ensure the confidentiality of the data transmission process, streaming media transmission security issues have been widespread concern. An implementation of the SRTP protocol system, a RTP protocol with security features, not only helps to defend against network security attacks but also provides users with privacy, encryption and authentication protection. Therefore, the research of decryption algorithm in MBMS is very important.