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Center for Education and Research in Information Assurance and Security

Watermarking with Quadratic Residues

Sam Wagstaff - CERIAS

Jan 16, 2002


Watermarking is a technique for adding a message, perhaps secret, to data to identify the owner or originator, or to detect tampering with the data.

We propose a scheme that can improve the security of the watermark in most known watermarking techniques. Our methods are faster and more robust than most known watermarking schemes.

Here is the general idea of our scheme: Let W be any watermarking method that encodes a 0 or 1, a bit of the watermark message, in a data item x according to some rules. We make no assumptions about which portions of x can be modified by W, and no assumptions about the nature of x.

About the Speaker

Before coming to Purdue, Professor Wagstaff taught at the Universities of Rochester, Illinois, and Georgia. He spent a year at the Institute for Advanced Study in Princeton. His research interests are in the areas of cryptography, parallel computation, and analysis of algorithms, especially number theoretic algorithms. He and J. W. Smith of the University of Georgia have built a special processor with parallel capability for factoring large integers.

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