| 摘要 |
PROBLEM TO BE SOLVED: To detect the copy use of an electronic check by communication between interested parties and to make a payment by a received electronic check. SOLUTION: The secret key and public key of each user and the public key of a bank are stored in an IC card possessed by the user. When the user 11 sends the electronic check to the other user 27, the respective public keys are mutually informed between the IC cards 45 and 47 and a random number is informed from the IC card 47 of a receiver 27 to the IC card 45 of a payer 11. The IC card 45 on a paying side changes the sequence of a progression included in the electronic check based on the random number, ciphers it by the public key of the receiver 27 and transmits it to the IC card 47 on a receiving side. The IC card 47 on the receiving side deciphers the electronic check by the secret key of the receiver 27, confirms the propriety of a bank signature by the public key of the bank, confirms whether or not the sequence of the progression is correctly changed corresponding to the random number and formally receives the electronic check. |
