Design and formal analysis of a group signature based electronic toll pricing system

Location-based vehicle services have been enduring a rapid growth with the prevalence of GNSS technologies, nowadays freely available for everyone. Given the nature of location data, privacy is of prime importance in services such as electronic tolling pricing (ETP) and pay-as-you-drive. In this paper, we first propose a new electronic toll pricing system based on group signatures – GroupETP which achieves a good balance between privacy and overhead imposed upon user devices. Second, wegiveacomprehensiveformalanalysisof GroupETP.Ouranalysis,conductedbyProVerif,requires someabstractionofthesystemandextensionstotheexistinganalysismethods. Theresultsshowthat GroupETP satisfies the desired properties – correctness, accountability and unlinkability.