| 摘要 |
PROBLEM TO BE SOLVED: To prevent deterioration of data due to overwrite of digital watermark. SOLUTION: A content protected by watermarking is distributed by utilizing a first transmission path. On the other hand, an encrypted second transmission path is prepared and a superposing watermark signal is transmitted. When watermarking is required, a watermark is superposed at the time of output to an analog connection terminal, for example. Alternatively, a watermark is decrypted from the second transmission path and subtracted from a signal obtained from the first transmission path, thus removing the watermark. Since a third party cannot take out the watermark signal in meaningful form on the second transmission path, the content can be protected against illegal use. |
