An Improved Size Invariant (n, n) Extended Visual Cryptography Scheme

2016 ◽  
Vol 12 (2) ◽  
pp. 80-88 ◽  
Author(s):  
Rahul Sharma ◽  
Nitesh Kumar Agrawal ◽  
Ayush Khare ◽  
Arup Kumar Pal
Keyword(s):  
Visual Cryptography ◽  
Visual Quality ◽  
Binary Image ◽  
Secret Message ◽  
Grayscale Image ◽  
Secret Image ◽  
Meaningful Shares ◽  
Connectivity Property ◽  
Visual Cryptography Scheme

In this paper, the authors have presented a (n, n) extended visual cryptography scheme where n numbers of meaningful shares furnish a visually secret message. Initially they have converted a grayscale image into binary image using dithering method. Afterwards, they have incorporated pixel's eight neighboring connectivity property of secret image during formation of meaningful shares. The scheme is able to generate the shares without extending its size. This approach has enhanced the visual quality of the recovered secret image from n numbers of shares. The scheme has been tested with some images and satisfactory results are achieved. The scheme has improved the contrast of the recovered secret image than a related (n, n) extended visual cryptography scheme.

scholarly journals An Improved Size Invariant (n, n) Extended Visual Cryptography Scheme

Cryptography ◽  
2020 ◽  
pp. 449-457
Author(s):  
Rahul Sharma ◽  
Nitesh Kumar Agrawal ◽  
Ayush Khare ◽  
Arup Kumar Pal
Keyword(s):  
Visual Cryptography ◽  
Visual Quality ◽  
Binary Image ◽  
Secret Message ◽  
Grayscale Image ◽  
Secret Image ◽  
Meaningful Shares ◽  
Connectivity Property ◽  
Visual Cryptography Scheme

In this paper, the authors have presented a (n, n) extended visual cryptography scheme where n numbers of meaningful shares furnish a visually secret message. Initially they have converted a grayscale image into binary image using dithering method. Afterwards, they have incorporated pixel's eight neighboring connectivity property of secret image during formation of meaningful shares. The scheme is able to generate the shares without extending its size. This approach has enhanced the visual quality of the recovered secret image from n numbers of shares. The scheme has been tested with some images and satisfactory results are achieved. The scheme has improved the contrast of the recovered secret image than a related (n, n) extended visual cryptography scheme.

scholarly journals Collusion Attacks in XOR Based RG-VSS

2019 ◽  
Vol 8 (10) ◽  
pp. 2339-2345
Keyword(s):  
Secret Sharing ◽  
Data Security ◽  
Visual Cryptography ◽  
Visual Quality ◽  
Visual Secret Sharing ◽  
Security Issue ◽  
Collusion Attacks ◽  
Secret Image ◽  
The Past

Visual secret sharing (VSS) is a well-known technique from the past few decades for data security. Recently, XOR based VSS has attracted many researchers due to its lossless or good visual quality of reconstructed secret image. Cheating in visual cryptography based VSS was introduced by Horng et. al. in 2006. Cheating occurs when a dishonest participant presents fake share and performs stacking of fake share with honest participants who have genuine share, thereby revealing the fake secret image instead of the original secret image. Cheating occurs when some XOR based VSS are exposed to collusion attacks. Here, in this paper, we have demonstrated and proved that there is a security issue in existing XOR based VSS schemes.

scholarly journals An optimization of color halftone visual cryptography scheme based on Bat algorithm

2021 ◽  
Vol 30 (1) ◽  
pp. 816-835
Author(s):  
Firas Mohammed Aswad ◽  
Ihsan Salman ◽  
Salama A. Mostafa
Keyword(s):  
Visual Information ◽  
Mean Squared Error ◽  
Signal To Noise Ratio ◽  
Visual Cryptography ◽  
Visual Quality ◽  
Bat Algorithm ◽  
Pixel Expansion ◽  
Low Contrast ◽  
Secret Image ◽  
Visual Cryptography Scheme

Abstract Visual cryptography is a cryptographic technique that allows visual information to be encrypted so that the human optical system can perform the decryption without any cryptographic computation. The halftone visual cryptography scheme (HVCS) is a type of visual cryptography (VC) that encodes the secret image into halftone images to produce secure and meaningful shares. However, the HVC scheme has many unsolved problems, such as pixel expansion, low contrast, cross-interference problem, and difficulty in managing share images. This article aims to enhance the visual quality and avoid the problems of cross-interference and pixel expansion of the share images. It introduces a novel optimization of color halftone visual cryptography (OCHVC) scheme by using two proposed techniques: hash codebook and construction techniques. The new techniques distribute the information pixels of a secret image into a halftone cover image randomly based on a bat optimization algorithm. The results show that these techniques have enhanced security levels and make the proposed OCHVC scheme more robust against different attacks. The OCHVC scheme achieves mean squared error (MSE) of 95.0%, peak signal-to-noise ratio (PSNR) of 28.3%, normalized cross correlation (NCC) of 99.4%, and universal quality index (UQI) of 99.3% on average for the six shares. Subsequently, the experiment results based on image quality metrics show improvement in size, visual quality, and security for retrieved secret images and meaningful share images of the OCHVC scheme. Comparing the proposed OCHVC with some related works shows that the OCHVC scheme is more effective and secure.

scholarly journals A Novel XOR-Based Threshold Visual Cryptography with Adjustable Pixel Expansion

2020 ◽  
Vol 10 (4) ◽  
pp. 1321
Author(s):  
Yusheng Guo ◽  
Xingxing Jia ◽  
Qimeng Chu ◽  
Daoshun Wang
Keyword(s):  
Visual Cryptography ◽  
Visual Quality ◽  
Pixel Expansion ◽  
Image Security ◽  
Secret Image ◽  
Security Applications ◽  
Average Contrast

A ( k , n ) visual cryptography (VC) scheme encodes a secret image into n shadows that are printed on transparencies distributed among a group of n participants secretly, and reveal the secret image by stacking no less than k of them. Its decryption requires no computation and attracts much attention in image security applications. The pixel expansion and contrast are two important characteristics to evaluate the visual quality of the revealed secret image for a ( k , n ) -VC scheme. The ( k , n ) XOR-based VC (XVC) schemes can greatly improve the visual quality including both pixel expansion and contrast. Previous methods require complex computation and result in high pixel expansion when they are used to construct such schemes. In this paper, we propose a pixel expansion adjustable ( k , n ) -XVC scheme, which allows pixel expansion to be changed among 2 k - 1 - 1 different values. It can ensure each pixel being exactly recovered with the same average contrast no matter it takes any pixel expansion value. The least pixel expansion is much smaller than previous schemes. Our scheme can be easily implemented based on any conventional OR-based ( k , n ) -VC (OVC) scheme.

Improved Extended Progressive Visual Cryptography Scheme Using Pixel Harmonization

2021 ◽  
Vol 15 (2) ◽  
pp. 196-216
Author(s):  
Suhas Bhagate ◽  
Prakash J. Kulkarni
Keyword(s):  
Secret Sharing ◽  
Visual Cryptography ◽  
Secret Sharing Schemes ◽  
Pixel Expansion ◽  
Secret Image ◽  
Secret Information ◽  
Meaningful Shares ◽  
Visual Cryptography Scheme

Security of information is of much concern in the modern internet era. Secret sharing schemes provide mechanism of encrypting secret information to prevent illicit usage. Visual cryptography is a secret sharing technique that facilitates encryption of a secret image. Visual cryptography allows us to effectively and efficiently share secrets among a number of trusted parties by hiding secrets within images. These images are encoded into multiple shares as per the rules indicated in basis matrices and later decoded by stacking required number of shares. Progressive visual cryptography has a specialty of recovering secret image as soon as more than one shares received gradually. Existing progressive visual cryptography schemes have severe limitations like data disclose on shares and higher pixel expansion. Improved progressive visual cryptography scheme deals with these limitations. Improved extended progressive visual cryptography scheme solves the issue of management of noise like meaningless shares by creating meaningful shares without any pixel expansion efficiently.

scholarly journals VISUAL CRYPTOGRAPHY FOR COLOR IMAGES

2013 ◽  
pp. 147-149
Author(s):  
ASHWATHIMESANGLA AO
Keyword(s):  
Secret Sharing ◽  
Visual Cryptography ◽  
Color Images ◽  
Secret Sharing Scheme ◽  
Secret Image ◽  
Secret Information ◽  
Host Image ◽  
Sharing Scheme ◽  
Visual Cryptography Scheme

Visual cryptography is a secret sharing scheme for encrypting a secret image, it is a perfectly secure way that allows secret sharing without any cryptographic computation, which is termed as Visual Cryptography Scheme (VCS). In this paper secret image is divided into shares (printed on transparencies), and each share holds some information. At the receiver this shares are merged to obtain the secret information which is revealed without any complex computation. The proposed algorithm is for color host image, divided into three color planes Red, Green, Blue and merged with secret image which is binarized and divided into shares. The decoding requires aligning the result obtained by merging color host image and shares, so as to obtain the secret image.

scholarly journals Meaningful Secret Image Sharing Scheme with High Visual Quality Based on Natural Steganography

Mathematics ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1452
Author(s):  
Yuyuan Sun ◽  
Yuliang Lu ◽  
Jinrui Chen ◽  
Weiming Zhang ◽  
Xuehu Yan
Keyword(s):  
Visual Quality ◽  
Secret Image Sharing ◽  
Secret Image ◽  
Image Sharing ◽  
Lossless Recovery ◽  
Sharing Scheme ◽  
Image Protection ◽  
Embedding Rate ◽  
Secret Image Sharing Scheme

The (k,n)-threshold Secret Image Sharing scheme (SISS) is a solution to image protection. However, the shadow images generated by traditional SISS are noise-like, easily arousing deep suspicions, so that it is significant to generate meaningful shadow images. One solution is to embed the shadow images into meaningful natural images and visual quality should be considered first. Limited by embedding rate, the existing schemes have made concessions in size and visual quality of shadow images, and few of them take the ability of anti-steganalysis into consideration. In this paper, a meaningful SISS that is based on Natural Steganography (MSISS-NS) is proposed. The secret image is firstly divided into n small-sized shadow images with Chinese Reminder Theorem, which are then embedded into RAW images to simulate the images with higher ISO parameters with NS. In MSISS-NS, the visual quality of shadow images is improved significantly. Additionally, as the payload of cover images with NS is larger than the size of small-sized shadow images, the scheme performs well not only in visual camouflage, but also in other aspects, like lossless recovery, no pixel expansion, and resisting steganalysis.

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