%0 Conference Paper %B Security and Watermarking of Multimedia Contents %D 2003 %T Visible Encryption: Using Paper as a Secure Channel %A Norberto Degara-Quintela %A Fernando Pérez-González %E Ping W. Wong %E Edward J. Delp %K 2-D-Bar-Codes %K data-hiding %K print-&-scan %K Two-dimensional-modulations %K visible-encryption %B Security and Watermarking of Multimedia Contents %S Proc. of SPIE %C Santa Clara, USA %V 5020 %G eng