| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide an optical recorder preventing the unauthorized copy, a recording medium and an optical reproducing device. SOLUTION: For the read-in starting time in a CD-R, the time specific to each maker is set as a vendor's code. The read-out starting time representing the recording capacity is arranged so as to be freely set by each maker. As to the ciphering method, both of a secret key method and an open key method are usable. When the secret key method is used, the ciphering is easily executed when data are additionally written since a decoding key obtained from the substrate information is used also as a ciphered key. Consequently, the secret key method is preferably used as the optical recording medium for writing once and/or rewriting the data. The ciphering method using chaos as one of the secret key methods is also available.</p> |
