| 摘要 |
PROBLEM TO BE SOLVED: To prevent an unjust use on a user side device in the protection of the copy-right of digital contents by operating a use monitoring program as a process with priority higher than a digital contents control program. SOLUTION: A data base 1 transfers ciphered digital contents to a user 4 through a network 3. Further, it transfers a cipher key for deciphering/ deciphering the ciphered digital contents to a digital contents control center 2. The control center 2 ciphers the cipher key to transmit it to the user 4. Further, the control center 2 transmits a monitoring program to the user 4. The digital contents control program incorporated in a device used by the user 4 controls the preservation/copy/transfer of the digital contents. The monitoring program interrupting into the control program detects that the preservation/copy/transfer being an irregular use are performed and embeds a visible electronic watermark in the original digital contents. |
