Arbitrary digital information is embedded within a stream of digital data, in a way that avoids detection by a casual observer and that allows a user to determine whether the digital data have been modified from their intended form. The embedded information may only be extracted as authorized and may...http://www.google.fr/patents/US6047374?utm_source=gb-gplus-shareBrevet US6047374 - Method and apparatus for embedding authentication information within digital data
Method and apparatus for embedding authentication information within digital ...
