New and efficient conditional e-payment systems with transferability

• We propose a new conditional e-payment scheme with transferability.
• Our scheme allows the coin to be transferred anonymously by a chain of payees.
• Our scheme does not require inefficient cut-and-choose techniques.
• Our scheme has lower computation and communication complexity.

Conditional e-payments (or e-cash) allow the user to anonymously cash a bank-issued e-coin at a future time if and only if a certain agreed-upon public condition is satisfied, which are useful in plenty of applications such as prediction markets, anonymous online betting, and securities trading. In this paper, we propose a new and efficient conditional e-payment system based on Chen et al.’s restrictive partially blind signature scheme. Compared to the existing conditional e-payment schemes  [2], [5] and [6], our construction requires neither the inefficient cut-and-choose techniques nor the complicated knowledge proof protocols and thus has lower computation and communication complexity. Another significant contribution of this paper is a conditional e-payment system with transferability which allows the coin to be further transferred anonymously by a chain of payees.