Method for hiding message data into media data and a method for extracting that hidden data

A data hiding method for hiding message information into media information, comprising the steps of:

• (a) obtaining a first frequency spectrum of the message information, the first frequency spectrum including a plurality of frequency components that represent features of the message information in real space;
• (b) extracting a base region from the first frequency spectrum, the base region comprising a selected band of the frequency components and including frequency components that represent features of said message information in real space;
• (c) copying the base region a plurality of times in frequency space to form a second frequency spectrum;
• and
• (d) operating the second frequency spectrum on the media information by executing an arithmetic based on both said intermediate information and said media information, to hide the message information into the media information and to facilitate identifying unauthorized copies of the media information.

A data extraction method for extracting message information from media information with said message information hidden multiply in frequency space, comprising the steps of:

• (a) obtaining, as first intermediate information, a frequency spectrum which has a plurality of base regions by operating said media information with said message information hidden therein, each of the base regions containing feature frequency components which represent features of said message information in real space;
• (b) specifying at least one of the base regions from said frequency spectrum obtained as said first intermediate information;
• (c) generating a frequency spectrum obtained by arranging said feature frequency components of said base region at predetermined positions on frequency space, as second intermediate information;
• and
• (d) extracting said message information hidden into said media information by performing inverse frequency transform of said second intermediate information, to facilitate identifying unauthorized copies of the media information.

A data extraction method for extracting message information from media information with said message information hidden multiply in frequency space, comprising the steps of:

• (a) obtaining a frequency spectrum which has a plurality of frequency components with respect to first intermediate information obtained by an arithmetic based on both said media information with said message information hidden therein and said media information with no message information hidden therein;
• (b) specifying at least one of the base regions from said frequency spectrum of the first intermediate information each of the base regions containing feature frequency components which represent features of said message information in real space;
• (c) generating a frequency spectrum obtained by arranging said feature frequency components of said base region at predetermined positions on frequency space, as second intermediate information;
• and
• (d) extracting said message information hidden into said media information by performing inverse frequency transform of said second intermediate information, to facilitate identifying unauthorized copies of the media information.

A system for embedding message information into media information, comprising:

• (a) means for obtaining a first frequency spectrum of the message information, the first frequency spectrum including a plurality of frequency components that represent features of the message information in real space;
• (b) an extractor for extracting a base region from the first frequency spectrum, frequency components that represent features of said message information in real space;
• (c) a generator for copying the base region a plurality of times in frequency space to form a second frequency spectrum;
• and
• (d) operating means for operating the second frequency spectrum on the media information to hide said message information into said media information to facilitate identifying unauthorized copies of the media information.

A system for extracting message information from media information with said message information hidden multiply in frequency space, comprising the steps of:

• (a) means for obtaining, as first intermediate information, a frequency spectrum which has a plurality of base regions by operating said media information with said message information hidden therein, each of the base regions containing feature frequency components which represent features of said message information in real space;
• (b) a specifier for specifying at least one of the base regions from said frequency spectrum obtained as said first intermediate information;
• (c) a generator for generating a frequency spectrum obtained by arranging said feature frequency components of said base region at predetermined positions on frequency space, as second intermediate information;
• and
• (d) an extractor for extracting said message information hidden into said media information by performing inverse frequency transform of said second intermediate information, to facilitate identifying unauthorized copies of the media information.

A program storage medium for executing a method of hiding message information into media information by a computer, the method comprising the steps of:

• (a) obtaining a first frequency spectrum of the message information, the first frequency spectrum including a plurality of frequency components that represent features of the message information in real space;
• (b) extracting a base region from the first frequency spectrum, the base region comprising a selected band of the frequency components and including frequency components that represent features of said message information in real space;
• (c) copying the base region a plurality of times in frequency space to form a second frequency spectrum;
• and
• (d) operating the second frequency spectrum on the media information to hide said message information into said media information to facilitate identifying unauthorized copies of the media information.

A program storage medium for executing a process of extracting message information from media information with said message information hidden multiply in frequency space by a computer, the medium comprising the steps of:

• (a) obtaining, as first intermediate information, a frequency spectrum which has a plurality of base regions by operating said media information with said message information hidden therein, each of the base regions containing feature frequency components which represent features of said message information in real space;
• (b) specifying at least one of the base regions from said frequency spectrum obtained as said first intermediate information;
• (c) generating a frequency spectrum obtained by arranging said feature frequency components of said base region at predetermined positions on frequency space, as second intermediate information;
• and
• (d) extracting said message information hidden into said media information by performing inverse frequency transform of said second intermediate information, to facilitate identifying unauthorized copies of the media information.