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Visual cryptography (VC) is a cryptographic technique that allows the encryption of a secret image into multiple shares. When the shares of a qualified subset are superimposed, the original secret image can be visually recovered. Region incremental visual cryptography (RIVC) is a class of visual cryptography; it encrypts a single image into a shared image with multiple levels of secrecy, and when decrypted, the secret image of each region can be gradually recovered. Traditional VC encrypts two black-and-white images, and its recovery method is equivalent to a logical OR operation. To obtain a better recognizability of the restored image, the XORoperator becomes a simple and efficient method of encryption and decryption. Because the XOR operation needs extra cost or equipment, if the equipment cannot be obtained, the scheme can be more flexible if the secret can still be restored by using OR decryption (superimpose). In this paper, we propose a novel RIVC that allows encoding multiple secret regions of a secret image into n random grids. Both the OR operation and the XOR operation can be used as operations during decryption. The proposed scheme is evaluated by simulation, and the experimental result shows its correctness, effectiveness and practicability. [ABSTRACT FROM AUTHOR]

A (k, n) visual cryptography (VCS) is used to build a system for secret sharing. The system divides a secret image (S) into n shares and recovers S by stacking shares bigger than or equal to k, while shares below k provide no information about S. The fundamental idea of VCS is that, rather than relying on mathematical or cryptographic skills, human vision can be used to decrypt the secret image. Typically, a Boolean OR operation can be used to indicate the stacking action in a VCS. The reconstructed secret image gradually darkens as more shares are stacked. However, this intractable issue can be overcome by designing an XOR-based VCS that uses the Boolean XOR operator rather than the OR operation. This indicates that by using the XOR-based VCS, higher image quality can be attained. Because the XOR operation requires the use of additional equipment, scholars consider that when no equipment is available, the traditional OR operation can still be used to reveal the secret images. That is, the secret image can be decrypted without a computing device by stacking enough shares, and if a lightweight computing device is available, a better-quality image can be produced via an XOR operation. In 2015, an RG-based (k, n) VCS to restore the secret image by using an OR or XOR operation was proposed. In this study, we improve the scheme and design a new (k, n) VCS, called (k, n) 2D_VCS to encrypt a secret image into n shares. The secret image can be recovered when k or more shares are gathered and stacked (OR operation) together or when an XOR procedure is utilized. Both the theoretical proof and experimental results show that the quality of the restored image obtained by our method is better than that of the previous methods. [ABSTRACT FROM AUTHOR]

A personal camera fingerprint can be created from images in social media by using Photo Response Non-Uniformity (PRNU) noise, which is used to identify whether an unknown picture belongs to them. Social media has become ubiquitous in recent years and many of us regularly share photos of our daily lives online. However, due to the ease of creating a PRNU-based camera fingerprint, the privacy leakage problem is taken more seriously. To address this issue, a security scheme based on Boneh–Goh–Nissim (BGN) encryption was proposed in 2021. While effective, the BGN encryption incurs a high run-time computational overhead due to its power computation. Therefore, we devised a new scheme to address this issue, employing polynomial encryption and pixel confusion methods, resulting in a computation time that is over ten times faster than BGN encryption. This eliminates the need to only send critical pixels to a Third-Party Expert in the previous method. Furthermore, our scheme does not require decryption, as polynomial encryption and pixel confusion do not alter the correlation value. Consequently, the scheme we presented surpasses previous methods in both theoretical analysis and experimental performance, being faster and more capable. [ABSTRACT FROM AUTHOR]

Secret sharing schemes (SSS) deal with activities relative to the secure distribution of a secret among a group of participants who then securely reconstruct the secret by collecting the shares which are held by individuals in qualified sets. A multi-secret sharing scheme (MSSS) is an extension of this where multiple secrets are shared simultaneously and where the performance is estimated using both the maximum improvement and average improvement ratios. In 2003, Crescenzo calculated a lower bound of maximum and average improvement ratios for a MSSS and proposed some special MSSS which achieve the lower bound of the maximum improvement ratio. Wang and Juan deployed a more flexible MSSS to achieve the optimal maxi-mum improvement ratio 2006. This paper provides evidence such that the optimal maximum improvement ratio and the optimal average improvement ratio may both be achieved through even simpler and more flexible MSSS through even simpler and more flexible multi-secret sharing schemes for any arbitrary n and m.

Naor and Shamir proposed the visual cryptography in 1995, they encrypted secret image into two meaningless random images, called shares, and it can be decrypted by human vision without any calculations. However, there would be problems in alignment when these two shares are staked by hand in practical. Therefore, this paper presents the fault-tolerant schemes of stacking two shares which are acquired from secret image encryption without pixel expansion. The main idea of these schemes is combining several pixels to be a unit, then encrypting every unit into a specific combination of pixels. It makes visual secret sharing scheme more practical.

Given a nonnegative integer r, a no-hole (r + 1)-distant coloring, called Nr-coloring, of a graph G is a function that assigns a nonnegative integer (color) to each vertex such that the separation of the colors of any pair of adjacent vertices is greater than r, and the set of the colors used must be consecutive. Given r and G, the minimum Nr-span of G, nspr(G), is the minimum difference of the largest and the smallest colors used in an Nr-coloring of G if there exists one; otherwise, define nspr(G) = ∞. The values of nsp1(G) (r = 1) for bipartite graphs are given by Roberts [Math. Comput. Modelling, 17 (1993), pp. 139–144]. Given r ≥ 2, we determine the values of nspr(G) for all bipartite graph with at least r - 2 isolated vertices. This leads to complete solutions of nsp–(G) for bipartite graphs. [ABSTRACT FROM AUTHOR]

In this paper, we consider two embedding problems in Cartesian product networks: one is the pancycle problem, which involves embedding cycles of various lengths in the given product network; and the other is the panconnectivity problem, which involves embedding paths of various lengths between any pair of distinct nodes in the given product network. We then apply our technical lemmas and theorems to derive new topological properties of two multiprocessor systems, namely, generalized hypercubes and nearest neighbor mesh hypercubes. [ABSTRACT FROM PUBLISHER]