  One of the greatest concerns related to the popularity of GPS-enabled devices
and applications is the increasing availability of the personal location
information generated by them and shared with application and service
providers. Moreover, people tend to have regular routines and be characterized
by a set of "significant places", thus making it possible to identify a user
from his/her mobility data.
  In this paper we present a series of techniques for identifying individuals
from their GPS movements. More specifically, we study the uniqueness of GPS
information for three popular datasets, and we provide a detailed analysis of
the discriminatory power of speed, direction and distance of travel. Most
importantly, we present a simple yet effective technique for the identification
of users from location information that are not included in the original
dataset used for training, thus raising important privacy concerns for the
management of location datasets.
