To secure effectively security of digital information, to realize effective prevention of theft, alteration breakage or the like of data, and to realize efficient reuse of the digital information by an authenticated user.

When generating an original management information 105 by enciphering provided digital information 104 and recording it in an optical disc 101b, security information including an inherent identification code 106a and a secret key 106b inherent to the digital information is recorded together therewith. When generating duplicated management information 107 from the optical disc 101b in response to a duplication request from the authenticated user and recording it in an optical disc 101c, duplicated security information 108 including an inherent identification code 108a, the secret key 106b and an authentication key 108c inherent to the user is recorded together therewith.