摘要： 为增强数字电视条件接收系统的安全性，用户端宜采用“机卡分离”的方法。其中，设计既安全又切实可行的机卡认证及密钥协商协议是一个重要环节。该文根据机卡分离环境的需求，设计了一个基于身份的双向认证及密钥协商协议。该协议可以抵抗中间人攻击、交错攻击与反射攻击。并且与基于证书的协议相比，无需可信第三方的介入，协议双方具有较少的通信量，在智能卡端也具有理想的计算量和较小的存储空间。

关键词: 基于身份, 认证, 密钥协商, 机顶盒, 智能卡

Abstract: In order to enhance the security of digital TV donditional access system, it is necessary to separate smart card and set-top box. So designing a secure, practicable mutual authentication and key agreement system between smart card and set-top box is critical. After analyzing the practical requirement, the paper proposes a mutual authentication and key agreement protocol based on identity-based public key cryptosystem. This protocol can resist man-in-the-middle attack, reflecting attack and interleaving attack. Moreover, comparing with certificate-based protocol, this protocol does not need the help of trusted third party. And it has less traffic, needs reasonable smart card computing amount and less storage space.

Key words: Identity-based, Authentication, Key agreement, Set-top box, Smart card