Digital color encryption using a multi-wavelength source Digital color encryption using a multi-wavelength source

DAFNE AMAYA; MYRIAN TEBALDI; ROBERTO TORROBA; NÉSTOR BOLOGNINI

Campinas (San Pablo, Brasil)

Congreso; VI Reunión Iberoamericana de Óptica (VI RIAO) y IX Encuentro Latinoamericano de Óptica, Lásers y sus Aplicaciones (IX OPTILAS); 2007

Instituto de Física Gleb Wataghin (IFGW) - UNICAMP

We propose a color image encryption by using digital joint transform correlator (JTC) architecture and wavelength multiplexing. In this arrangement, the color image to be encrypted is separated into three channels: red, green and blue. One JTC aperture has the information corresponding to a determined color channel embedded in a phase mask (object aperture), and the other JTC aperture contains the encrypting phase mask. The joint power spectrum reflects a behavior according to the double-aperture content and the illumination wavelength. The wavelength variation will produce a corresponding power spectrum change. The basic concept within this approach is that the speckle size is wavelength-dependent. Then, the wavelength change can be used to store the encrypted information associated to each color channel in the same media. We achieve the color storing by changing the illumination wavelength, while varying the color image content in the object aperture of the JTC architecture. The multiplexed power spectrum, which is sent to the authorizer receiver, does reveal neither the multiplexing operation nor the amount of stored information. We present digital results that confirm our approach.