Visual cryptography

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

On the Analysis and Design of Visual Cryptography With Error Correcting Capability

Abstract: A ( $k$ , $n$ ) visual cryptographic scheme (VCS) shares a secret image into $n$ shadow images that are distributed over $n$ involved participants When $k$ participants stack their shadow images, the secret is revealed The secret image of VCS is a visual secret Even though black/white dots in shadows suffer from interference by noise, the color may still retain the corresponding darkness with high probability Therefore, VCS has noise immunity for secret recovery Hence, it seems that there is no need to design a VCS that is robust to noise interference when transmitting or storing the files of shadow images However, some VCSs use the permutations of subpixels in shadow images as information to realize multiple decoding options For such schemes, we absolutely should ensure the correctness of the shadows In this article, we investigate a VCS with $t$ -error correcting capability (VCS- $t$ EC) To the best of our knowledge, VCS- $t$ EC is introduced for the first time Three ( $k$ , $n$ )-VCS- $t$ EC schemes are proposed: the separated scheme, the integrated scheme, and the nonsystematic scheme

A Novel Scheme for Mutual Authentication and Cheating Prevention in Visual Cryptography using Image Processing

Abstract: Visual cryptography (VC) is a method of encrypting a secret image into shares such that stacking a sufficient number of shares reveals the secret image. Shares are usually presented in transparencies. Each participant holds a transparency. In this paper, we studied the cheating problem in VC by malicious adversaries. We considered the attacks of malicious adversaries who may deviate from the scheme and create fake shares, whose stacking reveals a different Secret image. This paper proposes a solution to this Cheating problem by an Invisible and Blind Watermarking scheme. This scheme not only provides Authentication for the VC shares but also makes these secret shares invisible by embedding them into not so significant Host images. Thus secret shares are not available for any alterations by the adversaries who try to create fake shares. In the proposed invisible and blind watermarking scheme, every pixel of the binary VC share is invisibly embedded into the individual blocks of the host image sized 2x2. In this proposed scheme, the process of watermark extraction necessitates only the watermarked image and it doesn't require the original host image or any of its characteristics, making the proposed scheme blind. The efficiency of the proposed Cheating prevention scheme by Invisible Blind watermarking scheme has been demonstrated via the experimental results. A Perfect restoration technique is added to the Visual Cryptography Scheme to improve the quality of the restored secret image as well as memory space utilization. Hence the proposed Cheating prevention scheme along with Perfect restoration techniques provides a Novel Visual Cryptography scheme.

On the Extensions of (k, n)*-Visual Cryptographic Schemes

Abstract: A deterministic (k, n)*-Visual cryptographic scheme (VCS) was proposed by Arumugam et.al [1] in 2012. Probabilistic schemes are used in visual cryptography to reduce the pixel expansion. In this paper, we have shown that the contrast of probabilistic (k, n)*-VCS is same as that of deterministic (k, n)*- VCS. This paper also proposes a construction of (k, n)*-VCS with multiple essential participants. It is shown that in both deterministic and probabilistic cases the contrast of the (k, n)*-VCS with multiple essential participant is same as that of (k, n)*-VCS.

New Steganography Scheme in Halftone Images

Abstract: A so-called DHCED (Data Hiding by Conjugate Error Diffusion) method was proposed to hide a binary visual secret into halftone images such that the watermarked halftone image still has good visual quality. When decoding, the secret can be visually revealed by directly superimposing the halftone images. The authors claimed that the DHCED scheme reduced the boundary artifacts around the hidden visual secret in the watermarked halftone image than the previous schemes. However, the DHCED scheme does not achieve the perfect secrecy like the steganography scheme and is still compromised by the gradient-attack In this paper, by combining the halftoning technique and the visual cryptography technique, we introduce a new steganography scheme for halftone images. Our new scheme has the perfect secrecy that one cannot gain any information from the watermarked halftone image by either the human visual system or the computer program.