Privacy for Public Transportation

We propose an application of recent advances in e-cash, anony- mous credentials, and proxy re-encryption to the problem of privacy in public transit systems with electronic ticketing. We discuss some of the interesting features of transit ticketing as a problem domain, and pro- vide an architecture sucient for the needs of a typical metropolitan transit system. Our system maintains the security required by the tran- sit authority and the user while significantly increasing passenger privacy. Our hybrid approach to ticketing allows use of passive RFID transpon- ders as well as higher powered computing devices such as smartphones or PDAs. We demonstrate security and privacy features oered by our hybrid system that are unavailable in a homogeneous passive transpon- der architecture, and which are advantageous for users of passive as well as active devices.