Conditional e-payments with transferability

We introduce a novel conditional e-cash protocol allowing future anonymous cashing of bank-issued e-money only upon the satisfaction of an agreed-upon public condition. Payers are able to remunerate payees for services that depend on future, yet to be determined outcomes of events. Moreover, payees are able to further transfer payments to third parties. Once the payment is complete, any double-spending attempt by the payer will reveal its identity; no double spending by any of payees in the payee transfer chain is possible. Payers cannot be linked to payees or to ongoing or past transactions. The flow of cash within the system is thus both correct and anonymous. We discuss several applications of conditional e-cash including online trading of financial securities, prediction markets, and betting systems.

Research highlightsThis paper provides the following contributions:
► It proposes the concept of conditional e-cash, where transferred payments are conditioned on the outcome of a future event.
► It includes a solution extension to handle an offline bank.
► It extends the original solution to enable the transferability of conditional payments.