| 摘要 |
PROBLEM TO BE SOLVED: To imbed an digital watermark that easily detects a fraudulent act onto digital contents, when fraudulence such as forgery is made to the digital contents. SOLUTION: A file of original digital contents such as an image is read from an external storage medium 301, an imbedding device 304 imbeds a digital watermark, including its generating time to the read digital contents, an update time of the file is obtained from a clock 302 and described on the file. At reproduction, the generated time and the updated time are extracted from the file in the case of reproduction and compared, and when the difference is larger than a prescribed value, fraudulence is considered to have been made. |
