Identity Based Color Image Cryptography

An Identity based cryptography based on visual cryptography scheme was proposed for protecting color image. A color image to be protected and authentic entities such as account number, password, signature image are given as input. The binary key image is obtained by distributing the digital signature of obtained authentic entities. A secret color image which needs to be communicated is decomposed into three grayscale tones of Y-Cb-Cr color component. Then these grayscale images are halftoned to binary image, and finally the obtained binary images are encrypted using binary key image to obtain binary cipher images. To encrypt Exclusive-OR operation is done on binary key image and three half-tones of secret color image separately. These binary images are combined to obtain cipher. In decryption the shares are decrypted by applying Exclusive-OR operation on cipher and key, 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. Keywords— color image encryption; visual cryptography; identity based cryptography