of users from location-based attacks. The main idea of SKA is to replace the exact location of
a user U with an anonymizing spatial region (ASR) that contains at least K− 1 other users, so
that an attacker can pinpoint U with probability at most 1/K. Simply generating an ASR that
includes K users does not guarantee SKA. Previous work defined the reciprocity property as
a sufficient condition for SKA. However, the only existing reciprocal method, Hilbert Cloak …