| 摘要 |
PROBLEM TO BE SOLVED: To execute the control of utilization sequence of enciphered contents in off-line. SOLUTION: In the case of using a first key, a corresponding key is retrieved from a key storage section 12 based on an ID imparted to contents. A value of a field denoting a remaining number of times corresponding to the key in the key storage section 12 and when the value is zero, a host 10 sends the contents and the key to a token 20. A decoding section 22 of the token 20 uses the key to decode the contents and sends the result to the host 10. The host 10 checks an ID of a key used next to the present key from the key storage section 12. When the ID of the next key is not zero, the host 10 retrieves the next key based on the ID and conducts key activation processing when the corresponding key is found out. When the ID of the next key is zero, since the next key is not in existence, no key activation processing is conducted. The host 10 utilizes the decoded contents. |
