| 摘要 |
PROBLEM TO BE SOLVED: To provide electronic cash only by a hash function at payment and to speed up the payment processing of electronic cash by having a certifying function equivalent to a signature only by the hash function without using a digital signature among four of a bank device, a user device, a shop device and an issuing office device. SOLUTION: When a user pays a sum x1 to a shop, the user device 200 subtracts a sum x2 already paid using electronic cash C and the sum x1 from a face amount (x), performs hash operation to a random number (z) by the number of times corresponding to the remains, and transmits the result of that operation SU, the electronic cash C and the sums x1 and x2 to the shop device 400. The shop device 400 holds secret information SIS, performs hash operation b the number of times corresponding to the sums x1+x2 for received result SU, inspects whether that operation result coincides with the hash operation result S5 on the user side, and if it passes both the inspections, allows the payment of the sum x1 by the electronic cash C. |
