Information processing device, information processing method, information processing program, recording medium storing the program, and player

There is provided a player which efficiently restricts reproduction of information. The type of a recording disk ( 1 ) is determined by a disk distinction unit of a microcomputer ( 130 ), and a reproduction processing is immediately started unless the recording disk is determined as a DVD. If the disk is determined as a DVD, a key-bunch determination unit of the microcomputer ( 130 ) determines whether MKB information as a content for protection according to the CPPM technique is recorded or not. If not recorded, the reproduction processing is started immediately. Otherwise, if recorded, a wobble signal determination unit of the microcomputer ( 130 ) determines whether a wobble exists or not. If a wobble does not exist, the reproduction processing is started immediately. If a wobble exists, a restriction unit of the microcomputer ( 130 ) determines whether information has been properly recorded or not. If the information is an illegal copy, reproduction is inhibited. Reproduction of illegal copies is thus securely and efficiently restricted.