| 摘要 |
PROBLEM TO BE SOLVED: To prevent contents from being unauthorizedly used by a user when an expiration data is set in contents utilization. SOLUTION: The contents or a contents performance program are made to have information showing the expiration date. The expiration date information is embedded, for example, in an external file, the contents or the contents performance program. The expiration date information also comprises utilization start date and hour, utilization end date and hour, and the last utilization date and hour. Authentication is performed by using these data as authentication data at the time of utilizing the contents (when performing the contents performance program). As an authentication method, the performance program is allowed to be performed only when the two following requirements are met, for instance, when the contents are utilized. The current date and hour acquired from a system time must be between the utilization start date and hour (expiration date) (1), and the current date and hour must be later than the last utilization date and hour (the last access date and hour) (2). |
