一种基于坐标和的保护位置隐私近邻查询方法

空间定位和无线通信技术的成熟促进了基于位置服务(Location Based Service,LBS)的发展,用户通过向LBS服务器发送位置和查询信息获取相应服务。这种模式不可避免地带来对用户个体隐私的侵犯。随着用户对个体隐私信息安全的日益关注,如何在保护用户位置隐私安全下提供基于位置的查询服务成为研究的热点。现有的基于可信第三方的方法主要存在以下问题:(1)难以寻找满足要求的可信第三方;(2)可信第三方容易成为系统的瓶颈,造成系统查询效率和扩展性较差。针对这些问题,提出一种不依赖于可信第三方的隐私保护查询策略,即客户端通过向LBS服务提供方发送其当前位置的二维坐标之和,实现对查询发起用户位置隐私的保护。LBS服务器通过设置基于坐标和的查询处理策略将包含查询结果的候选解反馈给客户端,进一步通过对候选解的有效剪枝,有效降低通信开销以及服务器与客户端的处理代价。理论分析和实验结果表明,算法是可行的,能够有效解决依赖于可信第三方的系统带来的查询效率和系统扩展性较差的问题。

Location Privacy Preserving Nearest Neighbor Querying Based on Coordinates Accumulation

With the development of spatial positioning and wireless communication technology, location based services have been promoted greatly. Users can get services by sending their position information to LI3S server. But in this manner, it is inevitable to disclosure users' locations. With witnessed concerning on privacy preservation of individuals, it becomes pressing to provide location based query services without compromising users' location privacy. Most of existing solutions adopt a framework of trusted third parties(TTPs) to serve as intermediary between user clients and LBS server. These solutions suffer from the following issues; (1) Trusted third party is difficult to find, (2)TTP is inclined to be the system's bottleneck. Hence, it results in poor query efficiency and scalabihty. This paper proposed a TTP-free based method that submits coordinates accumulation instead of the user's real location. The client submits the query with coordinate accumulation of his location to the server. Special coordinate accumulation based query process is devised at the server side,which can generate candidate answers including the just query result. Further,an effective pruning strategy is applied to improve communication cost and workload at both client and server sides. Theoretical analysis and experimental results demonstrate that our method can solve the problems mentioned earlier effectively.