We describe novel methods of watermarking data using quadratic residues and random numbers. Our methods are fast, generic and improve the security of the watermark in most known watermarking techniques.
Mikhail J. Atallah,
Samuel S. Wagstaff,
"Watermarking with quadratic residues", Proc. SPIE 3657, Security and Watermarking of Multimedia Contents, (9 April 1999); doi: 10.1117/12.344677; https://doi.org/10.1117/12.344677