Efficient and privacy-preserving location-based services over the cloud

The location-based services (LBS) scheme has become an essential part of people's daily life, and it is widely used in various industries and cloud server applications. In LBS, users send the query regarding their current location to the cloud server. The cloud server collects the data related to the nearest hospital, restaurant, etc., corresponding to the received users' query and sends them. If the cloud server is malicious, it may reveal sensitive information about the user. Therefore, users may hesitate to share their queries with the cloud server. Moreover, the cloud server wants to monetize its services, and it only provides data to the user for a prescribed fee. Hence, simultaneously achieving users' query privacy and cloud server's data privacy is an important goal in LBS. Existing LBS schemes have restrictions that they cannot simultaneously achieve these types of privacy at low computation costs. This work proposes three LBS schemes using the oblivious transfer (OT) protocol. The first LBS scheme provides user's query privacy (in the presence of semi-honest cloud server) and cloud server's data privacy; the other two provide user's query privacy (in the presence of malicious cloud server) and cloud server's data privacy. All the proposed schemes require significantly less exponentiation and modulus operations than existing LBS schemes. Experimental results showed that the proposed schemes required less execution time on average than the existing LBS schemes.