A Recursive Threshold Visual Cryptography Scheme

This paper presents a recursive hiding scheme for 2 out of 3 secret sharing. In recursive hiding of secrets, the user encodes additional information about smaller secrets in the shares of a larger secret without an expansion in the size of the latter, thereby increasing the efficiency of secret sharing. We present applications of our proposed protocol to images as well as text.Comment: 8 page

Design and Implementation of a (2, 2) and a (2, 3) Visual Cryptographic Scheme

In this paper two methods for (2, 2) and (2, 3) visual cryptographic scheme(VCS) is proposed. The first scheme considers 4 pixels of input image at a time and generates 4 output pixels in each share. As 4 output pixels are generated from 4 input pixels dimension and aspect ratio of the decrypted image remain same during the process. The second scheme considers 2 pixels (1 block) of input image at a time and generates 3 output pixels in each share. Here probability of 1/3 for black pixel is maintained in each share. The scheme improves the contrast of output image. The dimension of revealed image is increased by 1.5 times in horizontal direction and remains same in vertical direction

Image Security using Visual Cryptography

Informations are being transferred through open channels and the security of those informations has been prime concerns. Apart from many conventional cryptographic schemes, visual cryptographic techniques have also been in use for data and information security. Visual cryptography is a secret sharing scheme as it breaks an original image into image shares such that, when the shares are stacked on one another, a hidden secret image is revealed. The Visual Cryptography Scheme is a secure method that encrypts a secret document or image by breaking it into image shares. A unique property of Visual Cryptography Scheme is that one can visually decode the secret image by superimposing shares without computation. Even to make the visual cryptography image shares more secure, public key encryption scheme is applied. Public key encryption technique makes image shares so secure that it becomes very hard for a third party to decode the secret image information without having required data that is a private key

An overview of visual cryptography

Abstract-Security has become an inseparable issue as information technology is ruling the world now. Cryptography is the study of mathematical techniques related aspects of Information Security such as confidentiality, data security, entity authentication and data origin authentication, but it is not the only means of providing information security, rather one of the techniques. Visual cryptography is a new technique which provides information security which uses simple algorithm unlike the complex, computationally intensive algorithms used in other techniques like traditional cryptography. This technique allows Visual information (pictures, text, etc) to be encrypted in such a way that their decryption can be performed by the human visual system, without any complex cryptographic algorithms. This technique encrypts a secret image into shares such that stacking a sufficient number of shares reveals the secret image. Shares are usually presented in transparencies. In this paper we provide an overview of the emerging Visual Cryptography (VC) and related security research work done in this area

Authentication for Multi-located Parties and Wireless Ad Hoc Networks

This thesis present a new authentication protocol for multi-located parties which uses an agent based scheme that divides the message into two parts together with a key distribution center to ensure stronger authentication. It also presents a protocol for wireless ad hoc networks to combat spamming and reduce traffic overload. The appropriate number of authentication agents was calculated for a wireless ad hoc network. Simulations were run for networks of 200, 1000, 2000 and 4000 nodes and it was found that 0.075 n (n is the number of nodes in the network) authentication agents work well to distribute the load evenly amongst them.Computer Science Departmen

Secret Sharing in Visual Cryptography

This thesis examines techniques for recursive hiding scheme for 3 out of 5 secret sharing and a probabilistic 2 out of 3 secret sharing scheme for gray scale images. In recursive hiding of secrets several messages can be hidden in one of the shares of the original secret image. The images that are to be hidden are taken according to their sizes from smaller to the largest. The first small secret image is divided into five different shares using visual cryptography. These shares are placed in the next level to create the shares of larger secret information. The shares at each consecutive level are distributed so that no one has access to all the shares of the smaller images, unless at least three participants come together to reveal the secret information, resulting in 3 out of 5 scheme. In the proposed protocol for gray scale images, the quality of the image is perfect when it is reconstructed for the construction of the final image based on the binary OR operation.Computer Science Departmen