Breaking the BOWS Watermarking System: Key Guessing and Sensitivity Attacks

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) [1], had as its main objective to enlarge the current knowledge on attacks to watermarking systems; In this paper the main results obtained by the authors when attacking the BOWS system are presented and compared with strategies followed by other groups. Essentially, two different approaches have been followed: exhaustive search of the secret key and blind sensitivity attacks. This work was partially funded by Xunta de Galicia under projects PGIDT04 TIC322013PR, PGIDT04 PXIC32202PM, and Competitive research units program Ref. 150/2006; MEC project DIPSTICK, reference TEC2004-02551/TCM and European Comission through the IST Programme under Contract IST-2002-507932 ECRYPT. ECRYPT disclaimer: The information in this paper is provided as is, and no guarantee or warranty is given or implied that the information is fit for any particular purpose. The user thereof uses the information at its sole risk and liability. Signal Theory and Communications Department, University of Vigo, Vigo 36310, Spain. E-mail: {pcomesan, fperez}@gts.tsc.uvigo.es.