Watermarking Attack: Security of WSS Techniques
F. Cayre, C. Fontaine and T. Furon
LIFL, University of Lille
In proceedings of International Workshop on Digital Watermarking -
Best Paper Award, To appear.
Most of watermarking techniques are based on Wide Spread Spectrum (WSS).
Security of such schemes is studied here in adopting a cryptanalysis
point of view.
The security is proportional to the difficulty the opponent has to
recover the secret parameters, which are, in WSS watermarking scheme,
the private carriers.
Both theoretical and practical points of view are investigated when
several pieces of content are watermarked with the same secret key.
The opponent's difficulty is measured by the amount of data necessary
to estimate accurately the private carriers, and also by the complexity
of the estimation algorithms.
Actually, Blind Source Separation
algorithms really help the opponent exploiting the information
leakage to disclose the secret carriers.
The article ends with experiments comparing blind attacks to these
new hacks. The main goal of the article is to warn watermarkers that
embedding hidden messages with the same secret key might is a dangerous