A Robust Privacy-Preserving Method for Continuous Location-Based Services
Abstract A critical issue for LBS (location-based service) adaptation is user privacy preservation. If the LBS does not well protect its users’ privacy, they will hesitate to use the service. A common method used by location-based services to preserve user privacy is to send a couple of dummy locations along with the true location to the service provider, so the provider would not know which is the true location. This method is simple and effective, but most users will keep using the LBS continuously, instead of one time only. If it is not carefully planned, using the dummy locations for continuous LBS may reveal users’ true locations. This research is to present a robust method to preserve users’ privacy for continuous location-based services by using the following steps:

1. Dummy locations are generated according to the following features:
   
   
   • They should not be too far away from the true location, and cannot be too close to each other either.
   • They should be located on the valid space like roads or parking lots.
   • Their number should be kept as low as possible like 3 to 5.
   
   The dummy locations along with the user’s true location are sent to the service provider.
2. The provider sends recommended locations back to the user, who will only make use of the recommended location based on the true location.
3. For the next service call, one location is generated from each previous location based on the following guidelines:
   
   
   • The location can not be too far away from its previous location.
   • The location must be located at valid space like on a road or a parking lot.
   • The distance between the location and its previous path (note that it is a path instead of a location) has to be greater than a threshold value.

On the other end, the service providers will be able to tell the locations are fake if the above features are not followed. This research investigates the flaws of using dummy locations for continuous location-based services to uphold user privacy from both the users’ and service providers’ points of view, and proposes innovative methods to close the loopholes, so more users will be willing to use location-based services.

Keywords
mobile computing, security, privacy, location-based service, LBS, continuous location-based service, dummy location

Conference