S2SI: A Practical Pseudonym Changing Strategy for Location Privacy in VANETs

Location privacy remains an open issue in VANETs. Although, frequently pseudonym changing is commonly accepted as solution to protect privacy in VANETs, many studies have been shown its weakness to provide the required level of privacy protection. In this paper, we propose a practical pseudonym changing strategy, called Silence & Swap at Signalized Intersection (S2SI). S2SI consists of two protocols, one for creating of safe silent mix zones and another for exchanging pseudonyms between vehicles under the control of RSUs within these zones. We evaluate the provided privacy protection of our strategy by developing anonymity set analytic model and by performing a simulative study of the strategy using the entropy of vehicles' anonymity set as the primary metric.