Ride and Hide: A Study on the Privacy of Ride Hailing Services

The rise of ride-hailing services (RHSs) is transforming our mobility. More and more people rely on such services on daily basis. In such services, users reveal their precise locations of origin and destination of desired trips to the service providers (SPs). Often, these locations are considered personally identifiable and further represent (sensitive) points of interest (POIs), e.g., a specific clinic one goes for treatment. Thus, service providers can collect and potentially abuse sensitive information on their user's mobility behavior. Therefore, despite of all the benefits of RHSs, they bring significant privacy risks to their users. One solution to this issue is to hide the origin and destination of a desired trip from the SP by obfuscating these locations while accepting some degree of a loss in service quality. In this paper, we consider a RHS using predefined taxi stops where users can request a ride-for-hire only from and to these predefined stops. This hides the POI of the user among other POIs around the stop. However, it also creates a quality loss in the form of additional walking distance to and from these stops to the actual origins and destinations. In this paper, we analyze both the privacy and the quality loss in such a service and compare this scenario to the conventional scenario of RHSs in which users can request a ride-for-hire to their precise trips' origins and destinations. We apply the so-called m-unobservability to measure the privacy gain in the case of the predefined stops. Furthermore, we use the (alpha, beta)-usefulness as a metric to measure the quality loss in the case of the predefined stops service. We conduct our evaluation using two real-world datasets; the NYC taxi dataset, and the NYC bus stop shelter dataset which we define as predefined taxi stops. Based on this, we analyze over 13.2 million recorded taxi trips in NYC and evaluate the corresponding privacy level in addition to the quality loss in case a predefined taxi stop would have been used instead.