COPYRIGHT PROTECTION SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide a copyright protection system that has a contrivance of surely inspecting whether or not a contents key obtained by decoding at a reproducing device is a substantial value. SOLUTION: In cases where contents are encrypted with an encryption key of a media bind and stored in recording media, a unidirectional function value of the medium key, media particular information and the contents key is calculated and stored in the media, and a reproduction side conducts the similar calculation and compares both the results. A reproduction device can raise attention to a user by ringing the alarm on the basis of the discrimination result.