Privacy Threats in Location-based Services

Location-based services (LBS) are those services that, based on the user’s current position, can provide location- aware information. Typical examples are map and navigation services, services that provide information on close-by public resources (e.g., gas stations, bus stops, pharmacies, and ATM machines), services that provide localized news (e.g., weather forecasts, road constructions, etc.), emergency services (911, 118, etc.), as well as more personalized services like proximity marketing or friend-finder. Private information refers to the information a user does not wish to be released associated with her identity. This includes political or religious orientation, health information, financial assets, or closeness to specific individuals or organizations. LBS services play a role in this context because both identity and private information can be directly or indirectly released through a single or a sequence of LBS requests. LBS requests can reveal, for example, a) information on the specific location of individuals at specific times, b) movement patterns (specific routes at specific times and their frequency), c) requests for sensitive services (closest temple for a specific religious worship), d) personal points of interest (frequent visits to specific shops, clubs, or institutions). A privacy threat occurs whenever the information contained in one or more requests issued by a given user can be used, possibly associated with external information, to associate the user identity with the private information. The study of privacy threats and protection techniques in LBS is a subtle and challenging research topic.