  Upcoming WiFi-based localization systems for indoor environments face a
conflict of privacy interests: Server-side localization violates location
privacy of the users, while localization on the user's device forces the
localization provider to disclose the details of the system, e.g.,
sophisticated classification models. We show how Secure Two-Party Computation
can be used to reconcile privacy interests in a state-of-the-art localization
system. Our approach provides strong privacy guarantees for all involved
parties, while achieving room-level localization accuracy at reasonable
overheads.
