  Geosocial networks are online social networks centered on the locations of
subscribers and businesses. Providing input to targeted advertising, profiling
social network users becomes an important source of revenue. Its natural
reliance on personal information introduces a trade-off between user privacy
and incentives of participation for businesses and geosocial network providers.
In this paper we introduce location centric profiles (LCPs), aggregates built
over the profiles of users present at a given location. We introduce PROFILR, a
suite of mechanisms that construct LCPs in a private and correct manner. We
introduce iSafe, a novel, context aware public safety application built on
PROFILR . Our Android and browser plugin implementations show that PROFILR is
efficient: the end-to-end overhead is small even under strong correctness
assurances.
