02124nas a2200193   4500008003900000245005100039210005100090300001300141490000600154520158100160100001901741700002301760700002301783700002101806700002001827700001801847700001901865856004601884       2010                          d00aMovement Data Anonymity through Generalization0 aMovement Data Anonymity through Generalization  a91–1210 v33 aWireless networks and mobile devices, such as mobile phones and GPS receivers, sense
and track the movements of people and vehicles, producing society-wide mobility databases. This is
a challenging scenario for data analysis and mining. On the one hand, exciting opportunities arise out
of discovering new knowledge about human mobile behavior, and thus fuel intelligent info-mobility
applications. On other hand, new privacy concerns arise when mobility data are published. The
risk is particularly high for GPS trajectories, which represent movement of a very high precision and
spatio-temporal resolution: the de-identification of such trajectories (i.e., forgetting the ID of their
associated owners) is only a weak protection, as generally it is possible to re-identify a person by observing
her routine movements. In this paper we propose a method for achieving true anonymity in
a dataset of published trajectories, by defining a transformation of the original GPS trajectories based
on spatial generalization and k-anonymity. The proposed method offers a formal data protection
safeguard, quantified as a theoretical upper bound to the probability of re-identification. We conduct
a thorough study on a real-life GPS trajectory dataset, and provide strong empirical evidence that
the proposed anonymity techniques achieve the conflicting goals of data utility and data privacy. In
practice, the achieved anonymity protection is much stronger than the theoretical worst case, while
the quality of the cluster analysis on the trajectory data is preserved.1 aMonreale, Anna1 aAndrienko, Gennady1 aAndrienko, Natalia1 aGiannotti, Fosca1 aPedreschi, Dino1 aRinzivillo, S1 aWrobel, Stefan  uhttp://www.tdp.cat/issues/abs.a045a10.php