A Location Privacy Aware Friend Locator

Laurynas Siksnys, Jeppe R. Thomsen, Simonas Saltenis, Man Lung Yiu,
and Ove Andersen

Department of Computer Science,
Aalborg University DK-9220
Aalborg, Denmark

Available: http://www.cs.aau.dk/~mly/SSTD09_friendloc.pdf

To appear as a "Short Research Paper" in

11th International Symposium on Spatial and Temporal Databases July
8-10, 2009 Aalborg, Denmark

http://sstd09.cs.aau.dk/

Abstract. A location-based service called friend-locator notifies a
user if the user is geographically close to any of the user's
friends. Services of this kind are getting increasingly popular due to
the penetration of GPS in mobile phones, but existing commercial
friend-locator services require users to trade their location privacy
for quality of service, limiting the attractiveness of the services.
The challenge is to develop a communication-efficient solution such
that (i) it detects proximity between a user and the user's friends,
(ii) any other party is not allowed to infer the location of the user,
and (iii) users have flexible choices of their proximity detection
distances. To address this challenge, we develop a client-server
solution for proximity detection based on an encrypted, grid-based
mapping of locations. Experimental results show that our solution is
indeed efficient and scalable to a large number of users.