| 摘要 |
PROBLEM TO BE SOLVED: To enable off-line electronic money transaction with high safety. SOLUTION: Respective electronic money cards 15 (15A and 15B) store their secret keys and an open key, and signature key obtained by multiplying their secret keys by the secret key of a bank center 10. To transfer electronic money from the electronic money card 15A (transmission source) to the 15B (transmission destination), the transmission source sends its open key to the transmission destination. The transmission destination sends transaction information, obtained by using the received open key, its secret key, and a random number, to the transmission source. The transmission source generates a 1st and a 2nd signature on the basis of the received transaction information, its secret key, the signature key, and the open key and sends it to the transmission destination together with the electronic money. The transmission destination calculates 1st and 2nd pieces of inspection information on the basis of the 1st and 2nd received signatures, decides whether or not the 1st and 2nd pieces of inspection information have the same value, and sends a transaction validation signal to the transmission source when they have the same value, but sends a transaction invalidation signal to the transmission source when not. |
