Digital contents copying inhibition apparatus, digital contents copying inhibition method, and computer products

The present invention relates to a digital contents copying inhibition apparatus which can prevent digital contents recorded in a music CD, a CD-ROM or the like from being copied into various types of recording media for inhibition of illegal distribution of the digital contents, a reproducible recording medium in which the digital data processed by the apparatus is recorded, a digital contents copying inhibition method, and a computer-readable recording medium in which a program for making a computer execute the method is recorded, and further to a reproducible recording medium in which the digital data processed by the method is recorded. The digital contents copying-inhibition apparatus comprises a guard data storage section which stores a guard data. This guard data is for appending to audio or video digital data which can be expressed as amplitude of the contained frequency component. Presence of this guard data becomes apparent only when the audio or video digital data is reproduced after the data has been compressed once. The apparatus further comprises, a peak detection section which identifies a position of a digital value having a prespecified increase rate and a prespecified amplitude among a plurality of digital values each constituting the digital data, a data analysis section which sets a flag for a digital value located at a position away from the peak position by a prespecified number and also sets a plurality of digital values within a prespecified range centering on the digital value for which the flag has been set as a data pattern, and a guard data appending section which identifies a position where the data pattern is located from the digital data and varies the digital data by appending the guard data to the identified position.