Optical disk and method of preventing fraudulent use of optical disk

Abstract

A method of preventing a fraudulent use of an optical disk having a read-write region and a read-only region, comprising the steps of: writing data for designating the boundary between the read-write region and the read-only region into a predetermined block of the optical disk; reading the data out of the predetermined block prior to the execution of the software recorded on an optical disk as an object of fraudulent use check; reading data out of a block which is assumed to be in the read-only region by reference to the data read out of the predetermined block, and writing the data read out of the block in the assumed read-only region into the same block; reading data out of a block which is assumed to be in the read-write region by reference to the data read out of the predetermined block, and writing the data read out of the block in the assumed read-write region into the same block; and judging that the optical disk as an object of fraudulent use check is not a fraudulent copy when the data writing operation is impossible in the block in the assumed read-only region but possible in the block in the assumed read-write region.