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Proceedings Paper

Cramer-Rao bound on watermark desynchronization parameter estimation accuracy
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Paper Abstract

Various decoding algorithms have been proposed in the literature to combat desynchronization attacks on quantization index modulation (QIM) blind watermarking schemes. Nevertheless, these results have been fairly poor so far. The need to investigate fundamental limitations on the decoder's performance under a desynchronization attack is thus clear. In this paper, we look at the class of estimator-decoders which estimate the desynchronization attack parameter(s) for using in the decoding step. We model the desynchronization attack as an arbitrary (but invertible) linear time-invariant (LTI) system. We then come up with an encoding-decoding scheme for these attacks on cubic QIM watermarking schemes, and derive Cramer-Rao bounds on the estimation error for the desynchronization parameter at the decoder. As an example, we consider the case of a cyclic shift attack and present some numerical findings.

Paper Details

Date Published: 2 March 2007
PDF: 11 pages
Proc. SPIE 6505, Security, Steganography, and Watermarking of Multimedia Contents IX, 65050H (2 March 2007); doi: 10.1117/12.705481
Show Author Affiliations
Shankar Sadasivam, Beckman Institute, Univ. of Illinois at Urbana-Champaign (United States)
Pierre Moulin, Beckman Institute, Univ. of Illinois at Urbana-Champaign (United States)


Published in SPIE Proceedings Vol. 6505:
Security, Steganography, and Watermarking of Multimedia Contents IX
Edward J. Delp; Ping Wah Wong, Editor(s)

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