MOTET: Mobile Transactions using Electronic Tickets
Daniele Quercia and Stephen Hailes


Abstract

There has been considerable work within the field of digital
cash protocols that aims to provide security guarantees
- non-repudiation, authentication, overspending checking
and off-line checking - whilst protecting anonymity. However,
considerably less attention has been given to the question
of electronic ticketing, and what exists has been rather
abstract or limited. Although eTickets aim at providing the
same security guarantees and privacy preservation properties
as digital cash, they are significantly different. Digital
cash derives much of its anonymity from the fact that the
denominations of electronic coins and notes are sufficiently
universal that it is not possible for the bank to know in advance
how they might be spent. In an eTicketing system,
however, this is not the case: at the point the ticket is purchased,
the ticket vendor knows for what it will be used and,
if a non-anonymous payment system is used, can associate
this with the customer. We present a novel protocol that enables
users to purchase and spend electronic tickets (eTickets)
of a range of two different types: those that can only be
used a certain number of times, and those that expire after
a certain date.