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.

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 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 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 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 A Novel Image Encryption Using Parity Based Visual Cryptography

2021 ◽  
Vol 26 (1) ◽  
pp. 135-142
Author(s):  
Kanusu Srinivasa Rao ◽  
Mandapati Sridhar
Keyword(s):  
Image Encryption ◽  
Visual Information ◽  
Visual Cryptography ◽  
Least Significant Bit ◽  
Pixel Expansion ◽  
Private Data ◽  
Xor Operation ◽  
Lsb Technique ◽  
Secured Data ◽  
Exclusive Or

The current era is mainly focused on secured data transmission and every organization takes preventive measures to protect network’s private data. Among different techniques visual cryptography is a prominent one that that encrypts the visual information and decrypts secret using mechanical operations without any computation, but each share need pixel expansion. In the current work, we propose an Image encryption technique using (n, n) Visual cryptography based on simple operations without pixel expansion. The proposed novel technique gives an image encryption using visual cryptography based on Least significant bit (LSB) technique in spatial domain and parity mechanism using Exclusive-OR(XOR) operation. developed for encrypting grey scale image. Image encryption and decryption uses simple Boolean operations. The technique provides better quality of shares and recovers without any loss.

Chaotic Map for Securing Digital Content

2016 ◽  
Vol 3 (1) ◽  
pp. 20-35 ◽  
Author(s):  
Dhiraj Pandey ◽  
U. S. Rawat
Keyword(s):  
Secret Sharing ◽  
Chaotic Map ◽  
Logistic Map ◽  
Visual Cryptography ◽  
Visual Quality ◽  
Digital Content ◽  
Digital Information ◽  
Pixel Expansion ◽  
Empirical Results ◽  
Logistic Chaotic Map

Progressive Visual Cryptography (PVC) is quite suitable for sharing sensitive digital data.Previous research on PVC, such as Fang et al. (2006) and W.P.Fang et al.(2008) were all carrying pixel-expansion problem and also gives a poor visual quality on the recovered stacked image. Recently, Hou&Quan (2011) have developed a progressive scheme for secret sharing. It is observed that shares generated by the scheme are free from pixel expansion problem, but shares are not fully secure. In this paper, a new progressive sharing algorithm based on logistic chaotic map has been proposed to overcome the said limitation of Hou (2011) scheme. The irregular outputs of the logistic map are used to encode a secret digital information carrying image. The performance of the algorithm in the scheme of Hou (2011) is critically analyzed and compared with new suggested scheme. Empirical results are presented to showcase the performance of the authors' proposed scheme in terms of its effectiveness (imperceptibility and security) and feasibility.

scholarly journals Visual Cryptography Using Binary Amplitude-Only Holograms [Invited]

2022 ◽  
Vol 2 ◽  
Author(s):  
Lina Zhou ◽  
Yin Xiao ◽  
Zilan Pan ◽  
Yonggui Cao ◽  
Wen Chen
Keyword(s):  
Visual Cryptography ◽  
Human Vision ◽  
Pixel Expansion ◽  
Secret Image ◽  
Secret Information

Visual cryptography (VC) is developed to be a promising approach to encoding secret information using pixel expansion rules. The useful information can be directly rendered based on human vision without the usage of decryption algorithms. However, many VC schemes cannot withstand occlusion attacks. In this paper, a new VC scheme is proposed using binary amplitude-only holograms (AOHs) generated by a modified Gerchberg-Saxton algorithm (MGSA). During the encryption, a secret image is divided into a group of unrecognizable and mutually-unrelated shares, and then the generated shares are further converted to binary AOHs using the MGSA. During image extraction, binary AOHs are logically superimposed to form a stacked hologram, and then the secret image can be extracted from the stacked hologram. Different from conventional VC schemes, the proposed VC scheme converts a secret image into binary AOHs. Due to the redundancy of the generated binary AOHs, the proposed method is numerically and experimentally verified to be feasible and effective, and possesses high robustness against occlusion attacks.

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