Privacy Preserving Scheme for Location-Based Services

Abstract

Homomorphic encryption schemes make it possible to perform arithmetic operations, like additions and multiplications, over encrypted values. This capability provides enhanced protection for data and offers new research directions, including blind data processing. Using homomorphic encryption schemes, a Location-Based Service (LBS) can process encrypted inputs to retrieve encrypted location-related information. The retrieved encrypted data can only be decrypted by the user who requested the data. The technology still faces two main challenges: the encountered processing time and the upper limit imposed on the allowed number of operations. However, the protection of users’ privacy achieved through this technology makes it attractive for more research and enhancing. In this paper we use homomorphic encryption schemes to build a fully secure system that allows users to benefit from location-based services while preserving the confidentiality and integrity of their data. Our novel system consists of search circuits that allow an executor (i.e. LBS server) to receive encrypted inputs/requests and then perform a blind search to retrieve encrypted records that match the selection criterion. A querier can send the user’s position and the service type he/she is looking for, in encrypted form, to a server and then the server would respond to the request without any knowledge of the contents of the request and the retrieved records. We further propose a prototype that improves the practicality of our system.