Abstract: An apparatus for preventing unauthorized reading/execution which does not necessarily requires such an extra storage region, but controls adverse effects to operating environment such as OS or the like, and contribute to restricting diffusion or distribution of unauthorized copies. An original CD-ROM readable by a driver stores original data, which in part contains modified data of a different value from a predetermined value to be generated by the driver. A copied CD-ROM stores copied data of the original data, and data of such predetermined value as generated by the driver at a time of making the copy.

Abstract: The present invention relates to an information recording medium on which information signals are recorded on the signal surface of a disc plate across a plurality of sectors in units of sectors and each of the plurality of sectors has at least a sector address and sector data. In particular, this information recording medium includes a first sector part, which includes at least one sector, and a second sector part which includes at least one sector having a sector address equal to the at least one sector in the first sector part but containing different sector data.