Method for making invertible digital watermarks with digital watermark techniques and cryptographic methods subdivides a digital document into sets with a watermark in one set dependent on cryptographic functions in another set.

摘要

A digital picture (1) to be made secure is displayed. Using a code selects data sets A (2) and B (3) in a pseudo-random manner. Data set A is subjected to the creation (4) of hash values to form an HA hash value for it. Data set B has hash values created for it to produce (5) an HB hash value and is compressed as a K compression (6) with run length coding and an ID so that ID + K + HB matches the cardinal numeral of data set B.