Visual Cryptography Research Paper

A Proposed Model of Visual Cryptography Technique

Ms.Hiral Rathod Ms.Hiral Parmar

ABSTRACT: In digital era security is the most important issue and cryptography is one of the mathematical solution related aspects of Information Security like integrity, confidentiality, data security, entity data origin authentication and authentication. Visual cryptography is another new solution or technique which provides information security with the help of simple algorithm. Use of the visual cryptography is easier than complex algorithms used in different techniques like normal cryptography (Symmetric and asymmetric). Through this technique we allow visual information (pictures, text, etc) that will be encrypted

They demonstrated a visual secret sharing scheme, where an image is broken up into n shares so that only someone with all n shares could decrypt the image, while any n − 1 shares revealed no information about the original image. It uses two transparent images. One image that contains random pixels and the other image contain the secret information. It is almost impossible to get the secret information from one of the images. Both transparent images and layers are needed to reveal the information. The simplest way to implement Visual Cryptography is it should be print onto a transparent sheet into the two layers. Using a similar idea, transparencies can be used to implement a one-time pad encryption, where one transparency is a shared random pad, and another transparency acts as the cipher text.

Working Principal of Visual Cryptography: Each pixel of the images is separated into smaller blocks. There are two blocks which contains white and black color blocks.. If the pixel is divided into two parts, there is one white and one black block. Same way, If it is separated in four equal parts, two are white and two are black blocks.. Below is the figure 1 that uses the pixels that are separated into 4

One transparent image, layer 1 shown in figure 2, contains one of the six possible states. Layer 2 which is shown in figure 3 is identical to layer 1, except for the pixels that should be black (contain information) when overlaid which is shown in figure 4. These pixels have a state that is opposite to the same pixel in layer 1. If both images are overlapped, the areas with identical states will look gray, and the areas with opposite states will be black.

If the pixel states of layer 1 are genuinely (crypto secure) random, both empty and information pixels of layer 2 will also have fully random states. One cannot determine if a pixel in layer 2 is used to create a black or grey pixel, since we need the state of that pixel in layer 1 (which is random) to know the overlay result. If all requirements for true randomness are fulfilled, Visual Cryptography offers absolute secrecy according to the Information Theory.

Visual Cryptography is used to protect the sensitive data sent over the internet, here first of all sender can sent the random one or more image to receiver and if sender has the message he can select the layer 2 image with message itself. If the receiver gets the two layer image, he can retrieve the image without using complex