1. MOTET: Mobile Transactions using Electronic Tickets September 2005 Daniele Quercia and Stephen Hailes CS department University College London {d.quercia,s.hailes}@cs.ucl.ac.uk SecureComm 2005

2. Daniele Quercia SecureComm 2005 D. Quercia and S. HailesMOTET: Mobile Transactions using Electronic Tickets 2 Outline Problems with eTicketing; Analysis of the requirements and limitations. Our Proposal: issuing, spending, and cashing phases.

3. Daniele Quercia3 ETicketing D. Quercia and S. Hailes SecureComm 2005 Problem: For need, current work is high-level and supported usage is limited. MOTET: Mobile Transactions using Electronic Tickets To enable eTicket-based transactions, we need standard eTicket format; standard protocol (!)

4. We propose a general-purpose eTicketing protocol. It supports: customer anonymity; revocable anonymity; non-repudiation; off-line checking; Daniele Quercia4 Our Proposal D. Quercia and S. Hailes SecureComm 2005 MOTET: Mobile Transactions using Electronic Tickets

5. Daniele Quercia5 Actors and Phases D. Quercia and S. Hailes SecureComm 2005 MOTET: Mobile Transactions using Electronic Tickets We consider three types of actors: Customer C; Ticket Agent TA; Service Provider(s) SPs. Our protocol comprises the following phases: eTicket issue phase; eTicket spending phase; eTicket cashing phase.

6. Daniele Quercia6 eTicket issue phase D. Quercia and S. Hailes SecureComm 2005 MOTET: Mobile Transactions using Electronic Tickets AFTER: C obtains an anonymous signed electronic ticket (eTicket). The issue phases comprises 2 subphases: bootstrapping; anonymous issuing.

7. Daniele Quercia7 eTicket issue phase - Boostrapping D. Quercia and S. Hailes SecureComm 2005 MOTET: Mobile Transactions using Electronic Tickets TA knows with whom is interacting and negotiates parameters. (i), (ii), (iii) (payment) signed (ii) and part of (iii), challenge for (i) response CTA signed remaining (i) (ie, )

8. Daniele Quercia8 eTicket issue phase – Anonymous issuing D. Quercia and S. Hailes SecureComm 2005 MOTET: Mobile Transactions using Electronic Tickets, ’s signature,, eTicket CTA

9. Daniele Quercia9 eTicket spending phase D. Quercia and S. Hailes SecureComm 2005 MOTET: Mobile Transactions using Electronic Tickets C spends eTicket at a Service Provider (SP). The phase comprises 4 steps: eTicket, next non-spent chain element challenge for personal info response service granted CSP

10. Daniele Quercia10 eTicket cashing phase D. Quercia and S. Hailes SecureComm 2005 MOTET: Mobile Transactions using Electronic Tickets Transfer of funds between SP and TA takes place. SP sends TA: eTicket; last spent chain element; response; If C overspent, two service providers have responses from C. Merging the two responses, TA reveals the customer identity.

11. Daniele Quercia11 Conclusion D. Quercia and S. Hailes SecureComm 2005 MOTET: Mobile Transactions using Electronic Tickets We proposed a general eTicketing protocol with the following features: customer anonymity; revocable anonymity; non-repudiation; off-line checking. Future work: substitute cut-and-choose; enable transferability;