Visual cryptography

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

A Tent Map and Logistic Map Based Approach for Chaos-Based Image Encryption and Decryption

Abstract: A cryptosystem incorporating multiple chaotic maps is proposed. Visual cryptography is necessary in today’s world to combat a large number of data thefts. Image encryption using chaotic maps is a common procedure, but it does not ensure absolute security. We use two maps in this paper, to curb the problem of security. The use of two chaotic maps has made the process of image encryption more secure. Image encryption is done using tent map, which is superimposed on another image encrypted using the logistic map. The encryption scheme has a greater keyspace because of two chaotic maps instead of one and thus has better security against statistical attacks.

A (k, n)-Threshold Progressive Visual Secret Sharing without Expansion

Abstract: Visual cryptography (VC) encrypts a secret image into n shares (transparency). As such, we cannot see any information from any one share, and the original image is decrypted by stacking all of the shares. The general (k, n)-threshold secret sharing scheme (SSS) can similarly encrypt and decrypt the original image by stacking at least k (≤ n) shares. If one stack is fewer than k shares, the secret image is unrecognizable. Another subject is progressive visual secret sharing, which means that when more shares are progressively stacked, the combined share becomes clearer. In this study, we constructed an advanced scheme for (k, n)-threshold SSS that can be encrypted in VC for any positive integers n ≥ k ≥ 2 through the method of combination, and the size of each share is the same as that of the original image. That is, no pixel expansion is required. Our scheme is novel, and the results from the theoretical analysis and simulation reveal that our scheme exhibits favorable contrast to that of other related schemes.

A Robust Three-Way Authentication System using Modified Random Grid based Reversible Style Visual Cryptography

Abstract: The growing possibilities of modern communications require a special means of confidential and intellectual property protection against unauthorized access and use. Cryptography provides important tools for the protection of information and they are used in many aspects of computer security. This paper makes use of encrypted secret sharing to increases the security level of hidden data and to provide Mutual Authentication of the users. The visual cryptography scheme is a perfect secure method that encrypts a secret image by breaking it into shadow images. A distinctive property of visual cryptography scheme is that one can visually, without computation, decode the secret by superimposing shadow images. The property of visual secret sharing in reversible style provides more security. This method not only can fast decode without causing pixel expansion but also increase the secret-hiding ratio. Random-Grid Algorithm is used to create secret shares without pixel expansion. This paper extends the capabilities of the Visual Cryptography as a mere secret sharing technique to a Novel Mutual Authentication provider. If one stacks two transparencies(shares) together straightforwardly, a secret image will appear. Stacking two transparencies after reversing one of the transparencies, another secret image will unveil. An attempt is made to provide two transparency three-way mutual authentication by using Visual cryptography in the reversible style. General Terms Visual Cryptography, Secret Shares, Mutual Authentication, Encryption, Secure Communication, Secret-hiding Ratio et.al

Secret Image Sharing Based on Error-Correcting Codes

Abstract: In traditional (k, n) threshold secret image sharing (SIS), a secret image is encrypted into n shadow images (also called shares) distributed to n associated participants. The secret image can be recovered by collecting any k or more shadow images, i.e., SIS is loss-tolerant. In SIS research domain, visual cryptography scheme (VCS) also called visual secret sharing (VSS) and Shamir's polynomial-based SIS scheme are the primary branches. Whereas, VCS mainly focuses on lossy recovery for binary secret image with pixel expansion, and most Shamir's polynomial-based SIS is not directly lossless. In this paper, we propose a SIS scheme based on error-correcting codes. Error-correcting code has the features of loss-tolerant and lossless recovery due to it has the strict mathematical relations of information values and check values, which has been widely used in signal communications. The loss-tolerant and lossless recovery features of error-correcting codes are utilized in the proposed scheme to achieve (k, n) threshold SIS with really lossless recovery. In addition, in the proposed scheme the size of each shadow image is smaller than the size of the original secret image. Experiments are conducted to evaluate the efficiency of the proposed scheme.