An encryption-based approach for protecting privacy in network-based location systems

Since the privacy of the users can be threatened by location-based services (LBS), many privacy preserving approaches have been proposed to protect the user location information during a request for LBS. Nevertheless, the user´s location information may still be exposed during positioning because of the nature of the unreliable wireless environment. This paper presents a secure network-based positioning system that can protect the privacy of the users by encrypting the location estimation. To preserve privacy, the proposed method exposes only an encrypted version of the user location based on asymmetric encryption schemes. When a network of base stations sends back the estimated result, it uses the public key to encrypt the data. The device will then use its private key to decrypt the location information. This intelligent scheme prevents the exposure of location information in the radio transmission and thus, protects the location privacy. Our experimental results show that, although the encryption in mobile device results in extra energy consumption, the computational time is acceptable in current high-level devices. The positioning accuracy is also comparable to the unencrypted results with a suitable choice of the scaling factor in the adopted RSA encryption techniques.