| 摘要 |
PROBLEM TO BE SOLVED: To automatically add information capable of certifying the date and hour in which a file is prepared when the file is prepared and saved. SOLUTION: For instance, a date and hour certification data producing part 16 that is hermetically sealed in a card shape is connected to a computer, and date and hour certification data at the time when a file produced by the computer is saved is produced. The part 16 has a clock part, enciphers date and hour shown by the clock part with an internally stored secret key and produces date and hour certification data. The part 16 also has an abnormality detection function and eliminates the secret key when it detects abnormality due to illegal behavior. A computer controlling part 11 adds the date and hour certification data produced by the part 16 to a file and saves it in an external storing part 13. |
