Visual Cryptography Scheme Research Articles

General Construction for Extended Visual Cryptography Scheme Using QR Codes

This article describes how a visual cryptography scheme, with one prominent feature—decrypting simply, has attracted much research attention since it was first proposed. However, meaningless shares remain a continuing challenge in the development of VCS. In this article, an extended visual cryptography scheme (EVCS) based on XOR operation is proposed, in which QR codes are utilized as the cover images of shares. By designation, all the shares generated in the scheme can be decoded by standard QR code readers with specific meaning. In addition, to achieve high sharing efficiency, a method of simultaneously sharing a secret QR code among multiple subsets is presented. Also, sufficient and necessary conditions of the method are analyzed with an integer programming model, providing a general construction approach for EVCS under arbitrary access structures.

Binary Image Random Grid (2, n)-Visual Cryptography Scheme

Majority of the data security ensures scientific systems. What's more related viewpoints on furnish for confidentiality, information security, substance Con-firmation Furthermore information root Confirmation. Visual cryptography may be another system which gives data security utilizing straightforward calculation Dissimilar to the complex, computationally escalated consideration calculations utilized within other systems in customary cryptography. This method permits visual data should make encrypted clinched alongside such an approach that their unscrambling could make performed by those human Visual framework (HVS), without whatever mind boggling cryptographic calculations. Pixel irregular Grids extends those purpose by Moni Naor and Adi Shamir All information in pixel grids will give secrecy and mystery without risking suspicion about an interloper. Those recommended plan complies with the technique for mystery offering plan the place mystery majority of the data is separated under Different greater part done negligible structure Furthermore will be further recouped once covering printed transparencies for the imparted data on it. Each of them will be that point approved for legitimacy. A endeavor need been constructed to utilize hardware rings with implant those mystery data with sure precise revolution. Also acceptance of the single person imparted over order will keep away from deceiving. In this paper we need aid portray each techniques from claiming VCS Also exhibited its similar contemplate utilizing favorable circumstances. What's more Hindrances.

Boolean Operation Based Visual Cryptography

A ( $k$ , $n$ )-Traditional Visual Cryptographic Scheme (VCS) based on basis matrices encoded a secret image into $n$ shadow images distributed among $n$ participants. When any $k$ participants superimposed their shadow images, the secret image can be visually revealed. This stacking operation in decoding process is equivalent to perform OR operation. Basis matrices of a ( $k$ , $n$ ) OR-operation based VCS (OVCS) have been proved in the ( $k$ , $n$ ) XOR-operation based VCS (XVCS) underlying XOR operation to enhance the contrast $2^{(k-1)}$ times. Although XOR operation has been used to excavate good property of basis matrices in OVCS, other properties of basis matrices are obviously ignored in visual cryptography. In this paper, we define two new Boolean-operation based VCSs, AND-operation based VCS (AVCS) and NOT-operation based VCS (NVCS), and prove that basis matrices in a ( $k$ , $n$ )-OVCS can be used as basis matrices in ( $k~n$ )-AVCS and ( $k$ , $n$ ) NVCS, respectively. Furthermore, we obtain a general converting formula of their contrasts among OVCS, AVCS, XVCS, and NVCS. With OVCS, there does not exist perfect whiteness. However, with other Boolean-operation based VCSs (XVCS, AVCS, and NVCS), there may exist this situation. Therefore, new contrast is also given to precisely evaluate visual quality of Boolean-operation based VCSs. Some observations and results demonstrate how to properly use these Boolean-operation based VCSs for decoding.

Information hiding scheme based on optical moiré-pixel matrix

An information hiding scheme for visual cryptography based on optical moiré-pixel matrix is introduced in this paper. The hiding information is formed by black and white unit square visual moiré-pixels with half of the period of a visual moiré pattern. The moiré-pixels can be accurately determined by designing the parameters in the original gratings. To verify the designed information hiding scheme, we experimentally conduct the sharing gratings to decrypt the information by using ordinary low-cost digital printing. The concealment of the sharing gratings is good to ensure the confidentiality. Both the simulation and experimental results show that the provoked scheme can afford enough security demand, yielding that the moiré-pixel matrix is a flexible platform for cryptographic security.

Safeguarding images over insecure channel using master key visual cryptopgraphy

Abstract Sharing secrets and safeguarding them while being sent over insecure channel is a crucial matter. Visual Cryptography still has the strong potential to secure this critical issue. In this paper, a new master key (n,n) visual cryptography scheme is proposed. The novelty of the proposed scheme is the generation of the master key using Station-to-Station Diffie Hellman algorithm. Moreover, one or more hierarchical shares could be generated for each secret image depending on the degree of security required. The performance of the shares generation technique is compared to others where it proves to be more robust to attacks. The algorithm satisfies all the basics of security: confidentiality, integrity and availability. This was evaluated by different tests like histograms, and entropy. Its security was analyzed against other vulnerabilities by evaluating the effect of man in middle attack and Evesdropping. Experimental results demonstrate that the scheme is highly secure.

Maximal contrast color visual secret sharing schemes

The transition of visual secret sharing from a black & white secret image to a color image is not straight-forward. There are several models of color superposition principle. In this paper we present color visual cryptographic scheme realizing monotone access structure. We first give a generic construction method to share a color image in same color model. In particular, our construction achieves maximal contrast. We also give a direct and efficient construction of visual secret sharing for $$(k,n)^*$$ -access structure.

An efficient XOR-based verifiable visual cryptographic scheme

Visual cryptographic (VC) schemes have been widely used in secure multimedia systems for data transmission and data storage. It divides a secret image into n random-seemingly share images printed on the transparencies. Superimposing the designed shares will display the recovered secret image which can be recognized by human visual system. It is very convenient to decode the secret since it requires no cryptographic knowledge and computation. However, there is a high chance for dishonest shareholders to present faked shares in the secret reconstruction phase, which would result in a huge damage to the honest shareholders. In this article, a secure approach to verify the cheating shares has been proposed to achieve fair reconstruction of the image secret. It is designed to share a verification image among the original shares of the XOR based VC scheme. It only increases pixel expansion by one to achieve the verification function. Cheating detection ability is attained by pairwise superimposing the shares so that any cheating behavior can be detected by the honest participant. The secret image is recovered and its recovered contrast becomes $\frac {m}{m + 1}$ times of the original contrast where m denotes the pixel expansion of the original scheme. The verification image is probabilistically recovered and its recovered contrast is $\frac {1}{2(m + 1)}$ . Compared with traditional verifiable (k,n)-VC schemes against cheating, it overcomes the drawbacks such as requiring additional shares, additional large pixel expansion, or lower contrast. The experimental results show that the visual quality of the recovered secret image is as good as expected. The security analysis and comparative results based on various aspects of VC schemes demonstrate the better efficiency of the proposed approach over existing schemes.

XOR-Based Visual Cryptographic Schemes With Monotonously Increasing and Flawless Reconstruction Properties

A $k$ out of $n$ visual cryptographic scheme [( $k, n)$ -VCS] encodes a secret image $P$ into $n$ transparencies (shares) in such a way that any $k$ shares reveal $P$ in a visual sense when they are superimposed (equivalent to the “OR” operation), while any $k-1$ or less cannot. A ( $k$ , $n)$ -XVCS achieves the same goal with a better contrast on the reconstructed result of any $k$ “XOR”ed shares. It has been proved that a ( $k, n)$ -VCS is also a ( $k, n)$ -XVCS. However, the monotonously increasing property (that any $k+1, k+2, \ldots , n$ shares also reveal $P)$ in most conventional ( $k, n)$ -VCSs is not guaranteed when they are applied as ( $k, n$ )-XVCSs. This paper aims at developing efficient and flexible constructions for ( $k, n)$ -XVCSs with minimal pixel expansions, such that the monotonously increasing property, or even the flawless reconstruction of $P$ when $n$ shares are “XOR”ed, could be additionally fulfilled. Property analyses and comparisons against Tuyls et al. ’s schemes are examined to demonstrate the applicability and superiority (in terms of the pixel expansion) of our schemes.

A novel approach for securing images using visual cryptographic scheme

Most applications require exchanging of information over insecure networks. The important issue concerned with respect to the images is to provide confidentiality and integrity. An efficient technique is proposed in order to provide protection to significant images through the digi-tal encryption scheme. Encryption before transmission is necessary for these images such that it makes sure that unauthorized person fails to access to any information. An efficient visual cryptographic approach is proposed for securing images by providing encryption during transferring an images or storing them. The technique proposed ensures that the images are inaccessible by unauthorized persons and also certifies confidentiality. In this proposed method to enhance security during data transmission across the network first the original image gets divided into multiple shares using logic operations and hence encryption technique is employed to these shares to maintain security. The binding of encryption and shares together called as encrypted shares are delivered and at the receiver side the reverse operation is carried out to retrieve back the original image. In the decryption process the decrypted share are layered to extract the actual image and if any shares are lost it is difficult to retrieve the information. The experimental result of the proposed method validates that the method will efficiently encrypt the image with a reduced amount of time without increasing the pixel size.

Improved Contrast for Threshold Random-grid-based Visual Cryptography

Pixel expansion and contrast are two major performance parameters for visual cryptography scheme (VCS), which is a type of secret image sharing. Random Grid (RG) is an alternative approach to solve the pixel expansion problem. Chen and Tsao proposed the first (k, n) RG-based VCS, and then Guo et al., Wu et al., Shyu, and Yan et al. significantly improved the contrast in recent years. However, the investigations on improving the contrast of threshold RG-based VCS are not sufficient. In this paper, we develop a contrast-improved algorithm for (k, n) RG-based VCS. Theoretical analysis and experimental results demonstrate that the proposed algorithm outperformers the previous threshold algorithms with better visual quality and a higher accuracy of contrast.

Enhancing multi-factor cheating prevention in visual cryptography based minimum (k, n)-connected graph

Recently, Lin et al. [29] introduced a (k, n) multi-factor cheating prevention visual cryptographic scheme (MCPVCS) by hiding verification images into shadow images. Through authenticating the verification image and the reconstructed image simultaneously, Lin et al.’s MCPVCS can prevent cheating attack that dishonest participants may collude and cheat the honest one to get a wrong secret image. However, the large n reduces the size of verification image and makes the verification difficult. In this paper, a (k, n)-MCPVCS with the large size of verification image is proposed. There are three main contributions for the proposed (k, n)-MCPVCS: (i) the verification condition in (k, n)-MCPVCS is redefined, (ii) a new minimum (k, n)-connected graph problem is introduced, on which the minimum number of verification images is determined, and (iii) the proposed (k, n)-MCPVCS with the large size of verification image can more easily authenticate the unambiguity of verification image.

Optimal visual cryptographic scheme with multiple share creation for multimedia applications

The criminal activity of hackers to retrieve the highly secured information on multimedia application generates major security concerned problems towards the human life. Basically, the visual cryptographic scheme generates numerous unreasonable image shares with specific information. The secret information hidden in the image can be retrieved by accumulating all the shares. The basic idea that relays on this cryptographic scheme is the encryption of image which hides the secret into m numerous image shares. By this process, it turns to be complex for the hackers to retrieve an original data of the image. Moreover, to increase the confidentiality and privacy of the original image there is in demand to make use of the efficient encryption algorithm. In this paper, the proposed visual cryptographic scheme is divided into three phases namely, (a) Separation of color bands, (b) Generation of numerous shares and (c) Optimal Encryption and Decryption. For optimal encryption and decryption of the image, we propose an OGWO based ECC (Elliptic Curve Cryptographic) approach. Initially, the input color image is separated into three color bands such as R, G and B. Subsequently, multiple image shares are generated based on the pixel measures. After this process, the shares of the image are partitioned into blocks and decrypt the original image using the optimal key generated by the OGWO (Oppositional Gray Wolf Optimization) algorithm. From the experimental analysis, we inferred that for the decrypted image PSNR achieved is 59.012, 0.11 for MSE and the CC is 1, without experiencing any deviations in the original image.

Perfect recovery of XOR-based visual cryptography scheme

Visual cryptography is an interesting secret sharing scheme, in which participants can observe the secret image by stacking their shares. However, the size expansion and distorted visual effect are two disadvantages of visual cryptography. In this paper, we focus on how to realize the perfect recovery by XOR-ing shares directly. First, we propose the definition of ideal access structure, which is the key point of perfect recovery of XOR-based visual cryptography scheme. The characteristics of ideal access structure are analyzed, and the construction algorithm of shares under ideal access structure is designed. Based on the ideal access structure, a new algorithm is proposed for dividing the general access structure into several ideal access structures, and the secret sharing and recovering algorithms for general access structure are presented. Furthermore, our method can also be utilized in color visual cryptography and multi-secret visual cryptography. The security and perfect recovery of our method have been proved theoretically. Compared with the previous schemes, the proposed scheme realizes the perfect recovery of secret image by XOR-ing shares directly, and the sizes of shares can be decreased efficiently compared with the previous schemes.

Security Concern and Countermeasures for Cheating in Visual Cryptography

As IT sector is ruling the world now,confidentiality and security of information has become the most important inseparable aspect in information communication system. Keeping in view the same, a new approach called Visual Cryptography (VC) has been suggested by many researchers but there are some limitations with this scheme and cheating is one of the main problem among them. This paper intends to show the basis of cheating in VC in terms of cheating process, its detection methods and its prevention methods suggested by various researchers along with their merits and demerits. Finally, a good Cheating Immune Visual Cryptography Scheme (CIVCS) has been discussed which states the properties to be adopted by every Visual Cryptography scheme to make it immune to cheating attacks.

Deterministic extended visual cryptographic schemes for general access structures with OR-AND and XOR-AND operations

In Visual Cryptographic Scheme (VCS) shares of the secret image look like random, whereas in Extended Visual Cryptographic Scheme (EVCS) the shares look like meaningful images. In the case of ideal contrast deterministic constructions for VCS, depending upon the access structure, each participant needs to hold one/multiple image shares with same size of the binary secret image and the secret image will be reconstructed without any change in resolution. In this paper, two deterministic constructions for EVCS with a relative contrast of 0.333 are proposed by utilizing the ideal contrast deterministic constructions for VCS as a building block. The proposed schemes are applicable to share secret binary images only. Theoretical analysis and comparison with other related works are given in this paper.

Collaborative Visual Cryptography Schemes

A ( $k,n$ )-conventional visual cryptography (VC) scheme is designed to share one secret and each participant takes one share. When some common participants are involved in multiple VC schemes for multiple secrets, each needs to take multiple shares. This procedure needs more shares, which is inconvenient. It is desirable that the collaboration between the VC schemes can allow each common participant to keep only one share. Simply merging or gluing together two traditional ( $k_{1}$ , $n_{1}$ )- and ( $k_{2}$ , $n_{2}$ )-VC schemes, after making their pixel expansions the same, might be able to facilitate the collaboration and allow each common participant to keep only one share. But there is a security risk that when a subset of $k_{1}$ participants are from the collection of noncommon participants, some from scheme 1 and some from scheme 2, they can reconstruct secret 1, which is inconsistent with the intention of the original scheme. Similarly, $k_{2}$ noncommon participants could reconstruct secret 2. This shortcoming is inherited from the brute-force combination of traditional schemes. Therefore, a more sophisticated mechanism is required; this is the main task of this paper. In this paper, we first transform collaborative VC (CVC) schemes into the multiple secrets VC scheme with a general access structure. The construction of the basis matrices in CVC scheme between two VC schemes is formulated into an integer linear programming problem that minimizes the pixel expansion under the corresponding security and contrast constraints. Also the collaboration among more VC schemes is constructed. Finally, the experimental results illustrate the construction procedure of the CVC scheme and demonstrate the effectiveness of the CVC scheme.

Overcoming Alignment Problem in Non-Identical Mathematical Support Visual Cryptography Schemes

An important problem in visual cryptography is the alignment problem. Although Liu, et al. have proposed a method for aligning the shares, there is still a problem with the non-identical mathematical support visual cryptography schemes. For overcoming this problem, the Three-Orthogonal-Point (3OP) method is proposed in this paper. Based on the experimental result it was proven that it can overcome the alignment problem, while the time complexity for aligning the shares is decreased significantly from O((m×A) 2 ) to O(m×AI) , for AI < A. The security is maintained, since an attacker cannot obtain any information related to the secret image.

Magic sheets: Visual cryptography with common shares

Visual cryptography (VC) is an encryption technique for hiding a secret image in distributed and shared images (referred to as shares). VC schemes are employed to encrypt multiple images as meaningless, noisy patterns or meaningful images. However, decrypting multiple secret images using a unique share is difficult with traditional VC. We propose an approach to hide multiple images in meaningful shares. We can decrypt multiple images simultaneously using a common share, which we refer to as a magic sheet. The magic sheet decrypts multiple secret images depending on a given share. The shares are printed on transparencies, and decryption is performed by physically superimposing the transparencies. We evaluate the proposed method using binary, grayscale, and color images.

Construction of Basis Matrices for (k, n) and Progressive Visual Cryptography Schemes

International Journal of Computer Sciences and Engineering (A UGC Approved and indexed with DOI, ICI and Approved, DPI Digital Library) is one of the leading and growing open access, peer-reviewed, monthly, and scientific research journal for scientists, engineers, research scholars, and academicians, which gains a foothold in Asia and opens to the world, aims to publish original, theoretical and practical advances in Computer Science,Information Technology, Engineering (Software, Mechanical, Civil, Electronics & Electrical), and all interdisciplinary streams of Computing Sciences. It intends to disseminate original, scientific, theoretical or applied research in the field of Computer Sciences and allied fields. It provides a platform for publishing results and research with a strong empirical component. It aims to bridge the significant gap between research and practice by promoting the publication of original, novel, industry-relevant research.

Visual Secret Sharing Schemes Encrypting Multiple Images

The aim of this work is to maximize the range of the access control of visual secret sharing (VSS) schemes encrypting multiple images. First, the formulation of access structures for a single secret is generalized to that for multiple secrets. This generalization is maximal in the sense that the generalized formulation makes no restrictions on access structures; in particular, it includes the existing ones as special cases. Next, a sufficient condition to be satisfied by the encryption of VSS schemes realizing an access structure for multiple secrets of the most general form is introduced, and two constructions of VSS schemes with encryption satisfying this condition are provided. Each of the two constructions has its advantage against the other; one is more general and can generate VSS schemes with strictly better contrast and pixel expansion than the other, while the other has a straightforward implementation. Moreover, for threshold access structures, the pixel expansions of VSS schemes generated by the latter construction are estimated and turn out to be the same as those of the existing schemes called the threshold multiple-secret visual cryptographic schemes (MVCS). Finally, the optimality of the former construction is examined, giving that there exist access structures for which it generates no optimal VSS schemes.