中文摘要：

物联网应用的安全和隐私保护问题是制约其进一步发展的关键因素，该文针对物联网中外部用户需要直接访问传感器节点获得信息的应用需求，基于异构传感器网络设计一个用户认证和密钥协商协议，保证信息传输的安全。协议在实现对所有参与者身份认证的同时，完成了用户和传感器节点之间的密钥协商。最后，该文从安全性和执行效率两个方面对所设计协议进行分析、比较，结果显示所设计协议是安全、高效的。

英文摘要：

Security and privacy are main restriction factors in the development of the Internet of Things（IOT） The external users need to directly access the sensor nodes to get data in IOT. In order to protect the security of data, we propose a user authentication and key agreement scheme based on heterogeneous wireless sensor networks The proposed scheme can verify the identity of participants and establish a shared key between the user and senor node.The detailed analysis of the proposed scheme shows that the scheme is secure and efficient.