Visual cryptography

About: Visual cryptography is a research topic. Over the lifetime, 1724 publications have been published within this topic receiving 25300 citations.

A new construction algorithm of visual crytography for gray level images

Abstract: In this paper a new construction algorithm of visual cryptography is presented. First, we extend SFCOD (space filling curve ordered dither - one of the techniques of halftoning) to transform a gray-level image into an image with fewer grayscale values. In addition, we extend the basic visual cryptography model to handle more than two grayscale values. Then the extended visual cryptography model can be applied to encode this image. This scheme satisfies the security and contrast conditions. It can reveal more details of original images in the decoded images than ordinary visual cryptography scheme.

A new fast and efficient visual cryptography scheme for medical images with forgery detection

Abstract: In the field of medicine, storing images in a secure way has become a challenge. In order to face this challenge of security, we propose an algorithm based on visual cryptography for black and white medical images. Here, we bring out a new approach to visual cryptography. The main advantage of this system is that there is no necessity for post processing of the image without which a good quality of the image is obtained. More security is provided by using the JPEG Ghost technique, which performs forgery checking on the reconstructed medical image. This paper proposes a technique of processing the medical image and dividing it into two shares in an unpredictable format. These two shares can be overlaid on which the original image is retrieved. This reconstructed medical image undergoes a forgery detection checking and determines whether the obtained image is forged one or not. This technique can be implemented in the medical field for storing images of X-ray, MRI scan, CT scan and Ultrasound scan in a secure way. Research is going on to import these images over networks in a compressed and secure manner.

kn Secret Sharing Visual Cryptography Scheme on Color Image using Random Sequence

Abstract: Visual cryptography is a special type of encryption technique where visual information (Image, Text etc) gets encrypted in such a way that decryption can be performed by Human Visual System with a computation free decryption process. The beauty of the visual secret sharing scheme is in its decryption process where without any complex cryptographic computation encrypted data is decrypted using Human Visual System (HVS). But the encryption technique needs cryptographic computation to divide the image into a number of parts let n such that at least a group of k shares out of n shares reveals the secret information, less of it will reveal no information. In this paper we have discussed a technique called random sequence which needs very less computation for k-n secret sharing.

Special type of circular visual cryptography for multiple secret hiding

Abstract: A special type of circular visual cryptography scheme for hiding multiple secrets is proposed. The circular shares are divided into two concentric rings: the outer ring and the inner ring. On the outer ring, two different secrets are hidden, where the second secret could only be revealed by rotating one share through a θ° angle off the other. In the inner ring, two more secrets are hidden. To reveal the first secret, one of the shares must be flipped over before stacking. The second secret can only be revealed after one of the shares is rotated through a β° angle in the flipped position. Through flipping and rotating, four secrets are encrypted in the shares. The secrets in the shares are secure, as the angles to rotate or which share to flip must be known beforehand.

Using multi-ringed shadow image of visual cryptography to hide more secret messages

Abstract: In this paper, we introduce a novel multi-ringed visual cryptography technique to hide secret messages on cylindrical surfaces of shares. Different secrets were hidden on the surface by fixed-angle segmentation. Four different secret messages were hidden such that the first two secrets can be revealed by stacking the hollow cylinders and rotating at a fixed angle and the next two, revealed by flipping one shadow image, stacked together and rotating at a fixed angle. The proposed method is novel for its simple hiding, data security and easy implementation.