| 摘要 |
PROBLEM TO BE SOLVED: To print and use an electronically issued coupon by detecting the forgery or alteration of the coupon and the illegal use of the coupon by a third person. SOLUTION: In issuing a coupon, a seller 100 prepares a coupon on which the irreversible converted value of a password transmitted from a consumer 200, coupon information to be protected from being altered, and the data signature of the coupon information is described as visible printed data. Therefore, even when the consumer 200 prints and uses the coupon, the digital signature described on the coupon is verified so that the alteration or forgery of the coupon can be detected. In using the coupon, the consumer 200 presents the same password as that when the coupon is issued to the seller 100, and the seller 100 compares the irreversible converted value of the presented password with the irreversible converted value described on the coupon so that the illegal use of the coupon by a third person can be detected. |
