A Privacy-preserving Proximity Testing for Location-based Services

Location-based service (LBS) applications have become increasingly popular in the past few years. These applications request users' mobile devices to provide location data in terms of a mobile user's position, movement direction, and speed. The proximity testing, as a core application of Locationbased services in social networking, enables a user to know whether people are within a given geometric range. However, private location data may be leaked due to the lack of corresponding privacy protection mechanism, which could result in serious security issues. To protect users' confidential location data, a privacy-preserving proximity testing (PPPT) using location grids is designed to improve the efficiency while protecting users' location privacy. The proposed scheme can test whether a person is within a given search area without the disclosure of any private location information. The security analysis and the performance evaluation results show that the proposed PPPT scheme is not only privacy-preserving, but also more efficient.