Towards Efficient and Privacy-preserving Location-based Comment Sharing

Location-based comment sharing is a popular social application, yet it often requires an access to privacy-sensitive user's locations, user's preferences, and user's comments. In this paper, we propose an efficient and privacy-preserving locationbased comment sharing scheme which allows users to post and search comments about locations without compromising the privacy of the selected location, comments and keywords used to search. Specifically, we propose a posting protocol and a searching protocol where the server is unable to know the locations and the keywords used by the post users and search users. In addition, a user's comment is only accessible to the users who belong to the same group. We provide a privacy analysis on the privacy properties, and evaluate our scheme through a real experiment with smartphones and Amazon Cloud services. The analysis and experimental results show that our scheme well preserves the privacy and is very efficient in terms of computation and communication overhead.