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TOMIN: Trustworthy Mobile Cash with Expiration-date Attached

Online mobile payment systems based on mobile cash provide privacy to customers and are feasible for real point of sale, virtual point of sale, and person-to-person mobile commerce scenarios. The merchant does not perform complex operations and the bank verifies the validity of the mobile cash before the merchant delivers the product. The bank must store the mobile cash spent in a database to prevent a double spending attack. In this paper, we propose an efficient mobile cash scheme in which the customer attaches the expiration date and deposit date. This property reduces the size of the bank’s database and the customer must spend the mobile cash before expiry. Moreover, the customer attaches the merchant’s identity into the mobile cash in the deposit phase. The scheme requires low computational cost and is suitable for mobile devices