Capacity of data-hiding system subject to desynchronization

摘要

Data hiding has been mainly studied in the last years. Many applications are targeted such as copy-rights management, meta-data embedding for rich-media applications, ... In all these applications, it is crucial to estimate what is the capacity of data hiding. Many works have then been made to study watermarking performance considering data-hiding as a kind of channel communication. However in all these studies, an assumption is made about the perfect knowledge of all attacks parameters (may be known in advance or later estimated with attacks modeling). More especially a malicious attacker may biased its attack so that parameters estimation may not be perfect (desynchronization in parameters). Furthermore, random geometrical attacks for images such as proposed by Stirmark benchmark (more generally desynchronization attacks) show that perfect synchronization may not also be achievable. These last kind of attacks are actually the most effective and lack of theoretical modeling for capacity estimation. We then propose a new model for taking into account desynchronization phenomenon in data hiding (coupled with degrading attacks - i.e. optimal SAWGN attacks). Further, thanks to the use of game theory, we state bounds on the capacity that may be obtained by data hiding systems when subject to desynchronization.