delta-Calculus: A New Approach to Quantifying Location Privacy

With the rapid development of mobile wireless Internet and high-precision localization devices, location-based services (LBS) bring more convenience for people over recent years. In LBS, if the original location data are directly provided, serious privacy problems raise. As a response to these problems, a large number of location-privacy protection mechanisms (LPPMs) (including formal LPPMs, FLPPMs, etc.) and their evaluation metrics have been proposed to prevent personal location information from being leakage and quantify privacy leakage. However, existing schemes independently consider FLPPMs and evaluation metrics, without synergizing them into a unifying framework. In this paper, a unified model is proposed to synergize FLPPMs and evaluation metrics. In detail, the probabilistic process calculus (called delta-calculus) is proposed to characterize obfuscation schemes (which is a LPPM) and integrate alpha-entropy to delta-calculus to evaluate its privacy leakage. Further, we use two calculus moving and probabilistic choice to model nodes' mobility and compute its probability distribution of nodes' locations, and a renaming function to model privacy leakage. By formally defining the attacker's ability and extending relative entropy, an evaluation algorithm is proposed to quantify the leakage of location privacy. Finally, a series of examples are designed to demonstrate the efficiency of our proposed approach.