Abstract: This paper proposes a solution to the secure Instant Messaging（IM） based on Elliptic Curve Cryptosystem（ECC） for a verity of security issues in IM.The solution applies ECC to key management and session key negotiation.So it can ensure the authentication，confidentiality and integrity of the communication in client-server and client-client.Experimental results show that the solution has high security and performance.

Key words: Instant Messaging（IM）, elliptic curve, certificate, security key

摘要： 针对即时通信中存在的各种安全问题，提出一种基于椭圆曲线密码体制的安全解决方案。方案使用了椭圆曲线密码体制进行密钥管理和会话密钥协商，保证客户端与服务器端，客户端与客户通信的确认性、机密性和完整性。实验结果表明，该方案具有较好的安全性和执行性能。

关键词: 即时通信, 椭圆曲线, 证书, 安全密钥