| 摘要 |
PROBLEM TO BE SOLVED: To cope with the steal, alteration and replay attach of degree information with a simple protocol at the time of paying with electronic degrees. SOLUTION: A degree issue requesting part 21 sends a set of request source identification information that is held by a request source identification information holding part 26 and request degrees that are inputted by a user and makes an issue request to a degree information issue center 10. When a degree issuing part 11 receives an issue request, it takes out request source identification information, decides that this request is a request for reissue of degree when the value is the same with one preceding request, and reissues degree information without charging. When it is request source identification information that is not used in the past, the part 11 decides that it is a new issue request, generates new degree information, performs signature on the degree information, charges it and issues it. A signature verifying part 22 verifies signature, etc., of issued degree information, and then requests an information updating part 24 to update information. The part 24 adds a new degree to a degree balance holding part 25 and updates information of a request source identification information holding part 26 to a new unique value. |
