  The plummeting cost of Bluetooth tags and the ubiquity of mobile devices are
revolutionizing the traditional lost-and-found service. This paper presents
SecureFind, a secure and privacy-preserving object-finding system via mobile
crowdsourcing. In SecureFind, a unique Bluetooth tag is attached to every
valuable object, and the owner of a lost object submits an object-finding
request to many mobile users via the SecureFind service provider. Each mobile
user involved searches his vicinity for the lost object on behalf of the object
owner who can infer the location of his lost object based on the responses from
mobile users. SecureFind is designed to ensure strong object security such that
only the object owner can discover the location of his lost object as well as
offering strong location privacy to mobile users involved. The high efficacy
and efficiency of SecureFind are confirmed by extensive simulations.
