Public Key Cryptosystem for Privacy Sensitive Location-Based Services

Almost every smartphone and wireless devices are equipped with GPS and other location-enabling technologies, which has enabled users to access location-based services, a popular service offered based on the user’s geographical location. In order to get a wide range of location-based services like locating nearby friends and locating nearby places/venues or public places (point of interest), users are forced to reveal their actual location; users are left with no option other than compromise location information causing privacy risk. In this paper, we revisited a protocol proposed by Muhammad N. Sakib and Chin-Tser Huang based on ECC concepts for proximity testing to preserve users location privacy. We made suitable modifications to the existing solution to overcome the false negatives in proximity testing and to reduce the unnecessary communication and computation cost. We have suggested an improvement to enable symmetric key exchange between communicating parties which can be used to securely share the location coordinates to calculate the actual distance between communicating parties. Our scheme withstands triangulation attacks and reveals no information about user’s exact location to either service providers or communicating parties or attackers, unless it is revealed by the user himself/herself.