Color image cryptography scheme based on visual cryptography

Abstract

A new cryptographic scheme proposed for securing color image based on visual cryptography scheme. A color image to be protected and a binary image used as key to encrypt and decrypt are taken as input. A secret color image which needs to be communicated is decomposed into three monochromatic images based on YCbCr color space. Then these monochromatic images are converted into binary image, and finally the obtained binary images are encrypted using binary key image, called as share-1 to obtain binary cipher images. To encrypt Exclusive OR operation is done between binary key image and three half-tones of secret color image separately. These binary images are combined to obtain share-2. In decryption the shares are decrypted, then the recovered binary images are inverse half-toned and combined to get secret color image. This scheme is more efficient for communicating natural images across diffident channel.