Patent ID: 6941253

Claim:
A control code read-out system in which a control code for access restriction corresponding to a playback control code of a recording medium is stored in a playback apparatus, and said control code stored in said playback apparatus is read-out when said recording medium is played back, and a comparison between said playback control code of said recording medium to be played back and said control code stored in said playback apparatus is performed, and playback of said recording medium is performed only when there is coincidence between said playback control code of said recording medium and said control code stored in said playback apparatus, said system comprising: means for reading out and decoding an encoded number of changes, to provide a decoded number of changes, from a number of changes storage unit and for determining whether the encoded number of changes has reached a pre-established upper limit means for encrypting said control code of said playback apparatus and storing an encrypted control code in a control code storage unit only when the number of changes read by said reading and determining has not reached said pre-established upper limit, means for incrementing the decoded number of changes by one, encrypting the incremented number of changes storing the incremented number of changes in said control code storage unit only when the number of changes read by said reading and determining means has not reached said pre-established upper limit, means for read-out said encrypted control code from said control code storage unit, and decrypting, when playing back said recording medium.