Proximity detection is one of the most common location-based application in daily life when user intent to find their friends who get into their proximity. The tremendous growth of the Internet has significantly reduced the cost of obtaining and sharing information about individuals, raising many concerns about user privacy. Spatial queries pose an additional threat to privacy because the location of a query may be sufficient to reveal sensitive information about the querier Studies on protecting user privacy information during the detection process have been widely concerned. Accordingly, a location difference-based proximity detection protocol is proposed based on the Paillier cryptosystem for the purpose of dealing with the above shortcomings. The framework can preserve users’location privacy in arbitrary local area and can maintain a good utility for both the system and every user. We evaluate our framework thoroughly towards real-world data traces. The results validate that the framework can achieve a good performance.

Keywords : Location privacy, Paillier cryptosystem, privacy preserving, private proximity detecting.