An Extended Visual Cryptography Scheme Using Balanced Block Replacement Method

In this paper Visual cryptography scheme is a cryptographic technique which allows the information which is visual such as printed text, handwritten notes and images to be encrypted in such a way that its decryption does not require a computer, it can be done by the human visual system. In extended visual cryptography, the meaningful cover images are added to the share images, which provides an opportunity to integrate visual cryptography and biometric security techniques. In this paper, a method has been proposed by using the extended visual cryptography scheme for processing halftone images that improves the quality of the share images and the recovered secret image for which the size of the share images and the recovered image can be preserved as same as that of the original halftone secret image. I. INTRODUCTION Visual cryptography is introduced by first in 1994 Naor and Shamir . Visual cryptography is a cryptographic technique which allows visual information (e.g. printed text, handwritten notes and pictures) to be encrypted in such a way that the decryption can be performed by the human visual system, without the aid of computers. With the rapid advancement of network technology, multimedia information is transmitted over the Internet conveniently. Various confidential data such as military maps and commercial identifications are transmitted over the Internet. While using secret images, security issues should be taken into consideration because hackers may utilize weak link over communication network to steal information that they want. To deal with the security problems of secret images, various image secret sharing schemes have been developed. Visual cryptography is of particular interest for security applications based on biometrics (2). The basic idea of visual cryptography can be illustrated with the traditional 2-out-of-2 scheme. In the (2, 2) scheme, every secret pixel of the image is converted into two share images and recovered by simply stacking two shares together.