To prevent a content provider from gaining no profit as a viewer skips a CM part that the content provider desires to show by forwarding only the CM part fast since restrictions etc., on reproduction of digital contents are not specially determined and then the viewer can skip the CM part.

Content data 202 comprising ciphered contents A and ciphered contents B comprise ciphered contents A1 (203) including CM/notice information etc., and ciphered contents B1 (204) including program contents etc., and a B1 encryption key 205 is embedded in a ciphered form in the ciphered contents A1 (203). The ciphered contents B1 (204) can be deciphered by extracting the B1 encryption key 205, and then the ciphered contents B1 (204) are not reproduced without reproducing the ciphered contents A1 (203), so the CM/notice information can not be skipped.

COPYRIGHT: (C)2008,JPO&INPIT