中文摘要：

无线传感器网络作为物联网感知层的核心组成部分,具有广阔的应用前景.然而,隐私泄露问题严重阻碍了传感器网络的发展.目前,传感器网络隐私保护技术已成为研究热点,其中隐私保护κ-NN（κ-Nearest Neighbor）查询协议是富有挑战性的问题.文中提出了面向双层传感器网络的高效的隐私保护κ-NN查询协议.首先,为提升查询效率,基于定向存储策略给出了适用于双层传感网的κ-NN查询架构.其次,针对管理节点俘获攻击,提出了一种新颖的隐私保护数据编码机制,通过为真实数据附加编码的方式,保证在不泄露数据隐私的同时精确地完成查询处理.再次,针对节点共谋攻击,设计了基于代理节点的单向数据隐藏机制,通过破坏普通节点与管理节点间数据的关联性实现抵御共谋攻击的目标.理论分析和仿真实验验证了协议的安全性和有效性.

英文摘要：

As an important part of Internet of Things （IoTs ）, Wireless Sensor Networks （WSNs）can be widely deployed in many physical environments for data collection and monitoring,such as oceans,volcanoes,animal habitats and battlefields.In these applications of WSNs,k Nearest Neighbors （k-NN）query which returns the nearest k objects of the given query location or value is very important for users to get the required information of monitoring areas.In consideration of the built-in resource limitation problems of single tier sensor networks,k-NN query can be more efficient in two tiered WSNs which contain a large number of resource constrained sensor nodes and fewer resource rich management nodes.However,relying on management nodes for data storage and query processing raises significant security concerns.Frequently,the deployment environments of WSNs are hostile and unpredictable,which threaten the data security and privacy.What is worse,the open nature of wireless communication makes it easy for adversaries to eavesdrop data packets or compromise nodes of sensor networks.Management nodes are more vulnerable to be compromised as they store massive data and serve as an important role for responding queries. The compromised management nodes bring serious security risks to the network and significantly restrict the development of two tiered WSNs.Therefore,in recent years,privacy preservation in two tiered WSNs has attracted more and more attention.Accurately answer k-NN query while preserving data privacy is a challenging problem.This paper presents an efficient privacy-preserving k-NN query protocol for two tiered WSNs.To the best of our knowledge,this paper is the first to consider collusion attacks for a value-based k-NN query in two tiered WSNs while fulfilling the preservation of privacy.To improve query efficiency,the architecture of k-NN query is proposed based on the directional storage strategy for two tiered WSNs.To resist management nodes compromising attacks,this paper proposes a novel privacy-preserv