Two different approaches for attacking BOWS

摘要

From December 15, 2005 to June 15, 2006 the watermarking community was challenged to remove the watermark from 3 different 512×512 watermarked images while maximizing the Peak Signal to Noise Ratio (PSNR) measured by comparing the watermarked signals with their attacked counterparts. This challenge, which bore the inviting name of Break Our Watermarking System (BOWS), and was part of the activities of the European Network of Excellence ECRYPT, had as its main objective to enlarge the current knowledge on attacks to watermarking systems; in this sense, BOWS was not aimed at checking the vulnerability of the specific chosen watermarking scheme against attacks, but to inquire in the different strategies the attackers would follow to achieve their target. In this paper the main results obtained by the authors when attacking the BOWS system are introduced. Mainly, the strategies followed can be divided into two different approaches: blind sensitivity attacks and exhaustive search of the secret key.