A Secure, Robust Watermark for Multimedia

1 I n t r o d u c t i o n The proliferation of digitized media (audio, image and video) is creat ing a pressing need for copyright enforcement schemes tha t protect copyright ownership. Convent ional c ryptographic systems permit only valid keyholders access to enc ryp ted data , but once such da ta is decrypted there is no way to t rack its reproduct ion or retransmission. Conventional c ryp tography therefore provides little protect ion against da ta piracy, in which a publisher is confronted with unauthorized reproduct ion of information. A digital wa te rmark is intended to complement c ryp tographic processes. It is a visible, or preferably invisible, identification code tha t is permanent ly embedded in the data, t ha t is, it remains present within the da t a after any decrypt ion process. In the context of this * Authors in alphabetical order