Resistance of Digital Watermarks to Collusive Attacks
Report ID: TR-585-98Author: Kilian, Joe / Shamoon, Talal G. / Zane, Francis / Matheson, Lesley R. / Tarjan, Robert E. / Leighton, Tom
Date: 1998-07-00
Pages: 23
Download Formats: |Postscript|
Abstract:
In many schemes for digital watermarking, an attacker in possession of a small fixed number of differently marked copies of a single document can easily produce an unmarked copy. In contrast, we show in this paper that if the watermarks have a component-wise normal distribution, then $Omega ig( {sqrt{n/ln m}},/ig)$ differently marked copies are required to successfully erase any mark with non-negligible probability. Here n is the dimensionality of the watermarks, and m is the number of differently marked copies distributed. This result holds in a specific but natural statistical model of watermarking.