中文摘要：

针对移动智能终端即时通信安全问题，提出了一种不可信互联网条件下移动智能终端安全通信方法。该方法设计并实现了一种在服务器和通信信道均不可信情况下的可信密钥协商协议。理论分析表明，所提出的密钥协商协议可以确保通信双方所协商会话密钥的真实性、新鲜性和机密性等诸多安全特性。密钥协商完成之后，基于透明加解密技术即可以确保即时通信双方语音／视频通信信息的机密性和完整性。真实移动互联网环境下的测试也表明该方法是高效和安全的，密钥协商可以在1～2s完成，攻击者无法获取即时通信的明文信息。

英文摘要：

Instant messaging is fundamental to various mobile Internet applications; however, it is still an open problem to implement secure instant messaging in untrusted Internet environment. An approach for secure instant messaging of mobile intelligent terminal was presented, and a protocol for Trusted Session Key Agreement （TSKA） was designed and implemented. Theoretical analysis shows that the proposed TSKA can ensure the authenticity, freshness and confidentiality of the negotiated session key, even in the condition that both of the instant messaging server and the communication channel are not trusted. After TSKA, instant audio/video messages can he sent to the other side in a confidential and complete way. Experimental results in real Internet environment show that the proposed approach is efficient and secure, the session key can be negotiated within 1 - 2 seconds, and attackers cannot obtain any plaintext of instant messages.