Two Step Share Visual Cryptography Algorithm for Secure Visual Sharing

This paper re - examines the problem of visual secret sharing for general access structures by using visual cryptograms of random grids (VCRG). Given a binary or color secret image shared by a set of n participants with a strong access structure, we devise t wo effective algorithms to produce a set of VCRG so that the members in each qualified set can reconstruct the secret image by superimposing their sh ares, while those in any forbidden set cannot. The basic 2 out of 2 visual cryptography model consists of a secret message encoded into two transparencies, one transparency representing the cipher text and the other acting as a secret key. Both transparencies appear to be random dots when inspected individually and provide no information about the original clea r text. However, by carefully aligning the transparencies, the original secret message is reproduced. The actual decoding is accomplished by the human visual system. Our algorithms do not require any extr a pixel expansion, which is indispensable and grows exponentially as n increases in conventional visual cryptographic schemes

Ubic: Bridging the gap between digital cryptography and the physical world

Advances in computing technology increasingly blur the boundary between the digital domain and the physical world. Although the research community has developed a large number of cryptographic primitives and has demonstrated their usability in all-digital communication, many of them have not yet made their way into the real world due to usability aspects. We aim to make another step towards a tighter integration of digital cryptography into real world interactions. We describe Ubic, a framework that allows users to bridge the gap between digital cryptography and the physical world. Ubic relies on head-mounted displays, like Google Glass, resource-friendly computer vision techniques as well as mathematically sound cryptographic primitives to provide users with better security and privacy guarantees. The framework covers key cryptographic primitives, such as secure identification, document verification using a novel secure physical document format, as well as content hiding. To make a contribution of practical value, we focused on making Ubic as simple, easily deployable, and user friendly as possible.Comment: In ESORICS 2014, volume 8712 of Lecture Notes in Computer Science, pp. 56-75, Wroclaw, Poland, September 7-11, 2014. Springer, Berlin, German

On Real-valued Visual Cryptographic Basis Matrices

Visual cryptography (VC) encodes an image into noise-like shares, which can be stacked to reveal a reduced quality version of the original. The problem with encrypting colour images is that they must undergo heavy pre-processing to reduce them to binary, entailing significant quality loss. This paper proposes VC that works directly on intermediate grayscale values per colour channel and demonstrates real-valued basis matrices for this purpose. The resulting stacked shares produce a clearer reconstruction than in binary VC, and to the best of the authors’ knowledge, is the first method posing no restrictions on colour values while maintaining the ability to decrypt with human vision. Grayscale and colour images of differing entropies are encrypted using fuzzy OR and XOR, and their PSNR and structural similarities are compared with binary VC to demonstrate improved quality. It is compared with previous research and its advantages highlighted, notably in high quality reconstructions with minimal processing

(N,N) Share Generation using Key Share approach for RGB image in VCS

Visual Cryptography is a secure and unique image encryption technique which protects image based secret. In visual cryptography image is encrypted into shares and in decryption process all or some of shares are super imposed with each other to decrypt the original secret image. In this technique no complex computation is needed for decryption of secret image which is the best advantage of Visual Cryptography Scheme. In this report various types of visual cryptographic techniques are discussed from previous research area. In this proposed system (N, N) VCS is used for encryption. It takes color image as an input and extracts in R, G and B components. After that it generates Key-Mask using Key-Mask generation algorithm which XOR-ed with R, G and B components and gives the key shares. Further XOR operation of these key shares with key mask generates the color shares. In decryption process image is recovered by XOR operation between key mask and color shares. It has a better security features compared to previous one

Visual Cryptography in Biometrics Passport

Every human being is unique in their nature such as traits and physical symptoms so computer science is using the biometric f or perfect identification within large database. Visual cryptography scheme is a cryptographic technique, which allows visual information e.g. printed text, handwritten notes, and picture to be encrypted in such a way that the decryption can be performed by the human visual system, without the aid of computers. Biometric passport is a smart card technology product created by use of biometric data and computer chip f or authenticate identification of citizen of particular country. Current passport has certain shortcoming. In the is method it is proposed to convert scan images of retina, fingerprint and face in secret image and meaningful shares by use of visual cryptography. In this method wi th use of Visual Cryptography three biometrics i.e . retina image, fingerprint image and fa ce image encrypted in two meaningful shares when these two share stacking on one another fingerprint image revealed and that can be verified with on the spot live fingerprint image for perfect identification accuracy