基于差分隐私的活动模式保护与时空轨迹发布方法

Differentially Private Activity Pattern and Spatial-Temporal Trajectory Publication

为了解决用户轨迹数据发布时的活动模式泄露问题,本文提出了一种基于差分隐私的活动模式保护与时空数据发布方法DPAP-STTP(Differentially Private Activity Pattern and Spatial-Temporal Trajectory Publication),该方法即保护了用户时空数据中活动模式的隐私,又可以保证所发布时空轨迹在服务建议生成上的有效性.在DPAP-STTP中,用户的活动模式表示为个人代表性轨迹的动静态信息,包括代表性轨迹的时空密度分布、时空路径分布、移动模式以及时空跨度.另外,DPAP-STTP通过隐私保护预算与隐私保护阈值对该动静态信息进行调控,然后根据调控后的动静态信息依次划分时空网格、重构轨迹所处时空区间、时空轨迹点随机采样,最终生成满足群体差分隐私的时空轨迹进行发布.本文的实验比较了DPAP-STTP与DP-STAR(Differential Private Synthetic Trajectory Publisher)、BNA(Bounded Noise-Adding)所生成的轨迹在特定时空范围内的有效性,证明DPAP-STTP不但可重构服从群体差分隐私的时空轨迹,而且在时空网格上维持了时空轨迹的有效性.

In order to solve activity pattern leakage problems while user trajectory data publishing,the paper propos⁃es the DPAP-STTP(Differentially Private Activity Pattern and Spatial-Temporal Trajectory Publication)method to publish spatial-temporal trajectories for achieving required services suggestions in support of users while preserving the privacy of activity patterns.In DPAP-STTP,users'activity patterns are represented as dynamic and static information of personal rep⁃resentative trajectories,including spatial-temporal density distribution,spatial-temporal trip distribution,mobility pattern and spatial-temporal span.Additionally,according to allocated privacy budget and specific privacy-preserving threshold,DPAP-STTP preserves the privacy of dynamic and static information,and uses perturbed information to divide spatial-tem⁃poral grids,reconstruct spatial-temporal passing grids,randomly select spatial-temporal point,and finally generate spatialtemporal trajectories with group differential privacy satisfied.The experiment in this paper compares the DPAP-STTP with DP-STAR(Differential Private Synthetic Trajectory Publisher)and BNA(Bounded Noise-Adding)for presenting the utility of DPAP-STTP trajectories.Consequently,the DPAP-STTP method is proved to generate spatial-temporal trajectories which follow the group differential privacy and maintain their utility in some spatial-temporal scopes.