The present invention has an object to provide a data processing apparatus which
can perform digital watermark embedding/extraction in accordance with manipulation,
editing, and compression. To achieve the object, the data processing apparatus
for performing compression processing on digital data comprises: a digital watermark
extracting device extracting additional information, embedded as a digital watermark,
from digital data; a digital watermark removing device removing the additional
information, embedded as a digital watermark, from the digital data; an irreversible
processing deice performing irreversible processing on the digital data; and a
digital watermark embedding device embedding the additional information as a digital
watermark in the irreversible-processed digital data.