3PLUS: Privacy-preserving pseudo-location updating system in location-based services

Location-Based Services (LBSs) are becoming increasingly popular with rapid developments of social networks and location aware devices, such as smartphones and tablets. Users query the LBSs server and get service information about their surroundings. Unfortunately, these queries may lead to serious security and privacy concerns. It is very hard for users to access LBSs while keeping their privacy at the same time. To deal with this problem, we propose a novel scheme, called 3PLUS. It can significantly improve users´ location privacy without reliance on the Trusted Third Party (TTP). Further more, it is simple to implement, and does not require changing the current structure of LBSs server. Users use a buffer to record the pseudo-locations, which come from both the history locations of herself and the encountered users. When two users encounter, by using their pseudonyms, they randomly choose a pseudo-location from their buffers and exchange with each other. Then she can find and submit k valid locations together to un-trusted LBSs server easily when the service is needed. Our evaluation results indicate us a hidden relationship between k, the buffer size S and exchanging number N.