Helping TicketMaster: Changing the Economics of Ticket Robots with Geographic Proof-of-Work

When tickets for popular events such as Hannah Montana concerts go on sale online, they sell out almost instantly. Unfortunately, a significant number of them are purchased by world-wide networks of ticket purchasing robots run by scalpers looking to turn a quick profit. Ticket outlets currently employ CAPTCHAs to slow down fully automated purchasing robots. Since the profit associated with scalping tickets is several orders of magnitude larger than the cost associated with paying humans to solve the CAPTCHAs, this approach has been ineffective. CAPTCHAs have a fundamental flaw when used to protect online tickets: the cost to solve them using humans is fixed and small. To address this problem, this paper explores a novel alternative based on geographically-driven proof-of-work. The crux of the approach exploits the observation that most legitimate clients are located geographically close to the event. By requiring every client to solve a cryptographic puzzle whose difficulty is based on their distance to the event, ticket purchasing robots must be placed close to each event in order to monopolize the tickets. This requirement significantly increases the cost of operating such networks. Using emulation and simulation, we demonstrate the utility of our approach in tackling the online ticketing problem.