EPS: Encounter-Based Privacy-Preserving Scheme for Location-Based Services

Location-Based Services (LBSs) gain increasing popularity with the development of social networks and mobile devices. The mobile users enjoy convenience by submitting their private information. Nonetheless, the users´ sensitive information may be abused by an un-trusted LBS server. Privacy concerned in LBSs can be categorized into two major types: location privacy and query privacy. In this paper, we propose a novel scheme, called Encounter-Based Privacy-Preserving Scheme (EPS), which allows a user to access an LBS server under the protection of k-anonymity on both her location privacy and query privacy. Without reliance on any Trusted Third Party (TTP), EPS uses a buffer on each user´s mobile device to collect the queried information of the encountered users. To achieve k-anonymity, a user needs to choose k-1 records from her buffer, with the help of our location obfuscating algorithm and querying algorithm, the user´s privacy can be protected. Evaluation results show the effectiveness and efficiency of our proposed EPS.