In reversible image secret sharing (RISS), the cover image can be recovered to some degree, and a share can be comprehensible rather than noise-like. Reversible cover images play an important role in law enforcement and medical diagnosis. The comprehensible share can not only reduce the suspicion of attackers but also improve the management efficiency of shares. In this paper, we first provide a formal definition of RISS. Then, we propose an RISS algorithm for a $(k,n)$ -threshold based on the principle of the Chinese remainder theorem-based ISS (CRTISS). In the proposed RISS, the secret image is losslessly decoded by a modular operation, and the original cover image is recovered by a binarization operation, both of which are just simple operations. Theoretical analyses and experiments are provided to validate the proposed definition and algorithm.

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Reversible Image Secret Sharing

In this article, we propose a key secret-sharing technology based on generative adversarial networks (GANs) to address three major problems in the blockchain: 1) low security; 2) hard recovery of lost keys; and 3) low communication efficiency. In our scheme, the proposed network plays the role of a dealer and treats the secret-sharing process as a classification issue. The key idea is to view the secret as an image during the secret-sharing process. If the user’s private key is text, we can covert the key text into an image called the original image. Specifically, we first divide the original image into original subimages by the image segmentation. Next, we encode each original subimage by DNA coding. Finally, we train the proposed network to find the key secret-sharing results. Our proposed scheme is not only a significant extension of the GANs but also a new direction for the key secret-sharing technology. The simulation results show that the scheme is secure, and both flexible and efficient in communication.

GAN-Based Key Secret-Sharing Scheme in Blockchain

Because of the importance of digital images and their extensive application to digital watermarking, block chain, access control, identity authentication, distributive storage in the cloud and so on, image secret sharing (ISS) is attracting ever-increasing attention. Share authentication is an important issue in its practical application. However, most ISS schemes with share authentication ability require a dealer to participate in the authentication (namely, dealer participatory authentication). In this paper, we design an ISS for a $(k,n)$ -threshold with separate share authentication abilities of both dealer participatory authentication and dealer nonparticipatory authentication. The advantages of polynomial-based ISS and visual secret sharing (VSS) are skillfully fused to achieve these two authentication abilities without sending a share by using a screening operation. In addition, the designed scheme has the characteristics of low decryption (authentication) complexity, lossless decryption and no pixel expansion. Experiments and theoretical analyses are performed to show the effectiveness of the designed scheme.

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A Common Method of Share Authentication in Image Secret Sharing

Secret Sharing-based Personal Health Records Management for the Internet of Health Things

Secret sharing is an information security technique where a dealer divides a secret into a collection of shares and distributes these to members of a group. The secret will only be revealed when a predefined number of group members cooperate to recover the secret. The purpose of this study is to investigate a method of distributing shares by embedding them into cover Quick Response (QR) codes in a secure manner using cryptographic keys. The advantage of this approach is that the shares can be disseminated over public channels, as anyone who scans the QR codes will only obtain public information. Only authorized individuals who are in possession of the required keys will be able to recover the shares. This also means that when group members cooperate to recover a secret, the group can determine the presence of an illegitimate participant if the person does not produce a valid share. This study proposes a protocol for accomplishing this and discusses the underlying security of the protocol.

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Cooperative Secret Sharing Using QR Codes and Symmetric Keys

Quick response (QR) codes have been widely used in applications, such as data storage and high-speed machine reading. Anyone can gain access to the information stored in QR codes; therefore, they are unsuitable for encoding secret information without the addition of cryptography or other protection. In this paper, we propose a visual secret sharing scheme to encode a secret QR code into several shares. In contrast with other techniques, the shares in our scheme are valid QR codes that can be decoded with some specific meaning by a standard QR code reader, thereby avoiding raising suspicion in potential attackers. Moreover, the secret message is recovered by XOR-ing the qualified shares, an operation that can easily be performed using smartphones or other QR scanning devices. Experimental results show that the proposed scheme is both feasible and reasonably secure. Our scheme’s high sharing efficiency is also highlighted in this paper.

Improved Visual Secret Sharing Scheme for QR Code Applications

The Quick Response (QR) code is designed for information storage recognizable by machine vision. With the popularity of QR code applications, the security of QR codes becomes hot issues concerned by many scholars. In this paper, a novel QR code with two-level information storage is designed to protect private messages. In the meantime, the public level can be directly decoded by any standard QR reader. In contrast to other studies, the computational complexity of the proposed scheme is reduced by combining with the theory of visual cryptography scheme (VCS). In addition, an important characteristic of the QR code, error correction capability, is preserved in this paper, guaranteeing the robustness to QR code damage. Experimental results and analysis show that the proposed scheme is both feasible and reasonably secure, further enriching the application fields and outperforming the previous schemes significantly.

A new two-level QR code with 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.

Perfect recovery of XOR-based visual cryptography scheme

In the past few years, visual cryptography scheme (VCS) has aroused much research attention and developed rapidly because of its simple decryption. However, meaningless shares remain a continuing challenge of VCS to its practical applications. In this paper, we propose a ( $k$ , $n$ )-VCS combining with QR codes. To enlarge the allowable maximum size of secret image, a probabilistic sharing model is utilized. Based on it, a secret sharing method is presented with high relative difference. Furthermore, we embed the initial shares into cover QR codes by using encoding redundancy. After that, each share is meaningful and can be read by any standard QR code reader. Different from previous work, error correction capacities of the covers are perfectly preserved. We also highlight that our scheme can be used to authenticate the security of QR codes from some uncertain sources. Finally, experimental results and comparisons are provided to show the feasibility and advantages of the proposed scheme.

Visual Cryptography Scheme With Meaningful Shares Based on QR Codes

Random grid (RG) is an alternative approach to realize a visual secret sharing (VSS) scheme. RG-based VSS has merits such as no pixel expansion and no tailor-made matrix requirement. Recently, many investigations on RG-based VSS are made. However, they need further improvements. In this paper, we obtain some improvements on RG-based VSS. Actually, two improved schemes are proposed, namely RG-based VSS for general access structure (GAS) with improved contrast and extended RG-based VSS with improved access structure. The first scheme can achieve better contrast than previous schemes. The second scheme reduces the chance of suspicion on secret image encryption by generating meaningful shares instead of noise-like shares in the first scheme, and improves the access structure from (k, k) to GAS while maintaining the property that the contrast of the recovered image is traded with that of share images by setting a certain parameter from small to large. Finally, theoretical analyses and experimental results are provided to demonstrate the effectiveness and advantages of the proposed schemes.

Bin Yu

Papers

Improved Visual Secret Sharing Scheme for QR Code Applications

A new two-level QR code with visual cryptography scheme

Perfect recovery of XOR-based visual cryptography scheme

Visual Cryptography Scheme With Meaningful Shares Based on QR Codes

Improved schemes for visual secret sharing based on random grids