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Visual cryptography scheme is a method of encrypting secret image into n noiselike shares. The secret im)age can be reconstructed by stacking adequate shares. In the past two decades, many schemes have been proposed to realize the cheating prevention visual cryptography scheme (CPVCS). Significantly, Ren et al. [9] first introduced the idea of CPVCS with the help of Latin square. Inspired by their work, in this article, a new reliable scheme is proposed. More precisely, to facilitate the certification process, we embed meaningful characters into the randomly chosen authentication patterns in each divided blocks. Furthermore, we fix the security vulnerability in the stacked results of share Sд and verification Verд, where 1 ≤ д ≤ n. Since the improved scheme encrypts the secret image by utilizing random grids, the generated shares have no pixel expansion. Finally, theoretical analysis and experimental results are conducted to evaluate the efficiency and security of the proposed scheme. [ABSTRACT FROM AUTHOR]

A common approach to increase test security in higher educational high-stakes testing is the use of different test forms with identical items but different item orders. The effects of such varied item orders are relatively well studied, but findings have generally been mixed. When multiple test forms with different item orders are used, we argue that the moderating role of speededness on item order effects cannot be neglected as missing responses are commonly scored as incorrect in high-stakes testing. If test-takers run out of time while not giving answers to easy items at the end of the test, they are penalised stronger than if instead they were unable to provide answers to difficult items. Using an illustrative real-data example of a speeded test, we show that the potential consequences of ignoring item order can be substantial with respect to test fairness. Our proposed solution consists of using a fixed item order across forms from the point at which the test may become speeded for some students. In this approach, the most time-intensive items are placed at the end of the test. A simulation based on real data of two university examinations from psychology students illustrates the usefulness of this approach. [ABSTRACT FROM AUTHOR]

Communication of information over the open network is always vulnerable to the data being transferred. Data could be of text, image, video or any other format. Classified data in the form of images, such as, medical record, medical images, insurance policy documents, bank statements, personal identification cards are communicated in these medium. Security to such data is an important concern. Visual secret sharing (VSS) is an encryption scheme to encode classified image data and dividing in to shares. The shares are communicated to the members from source. At the destination, the shares are decoded to reconstruct the classified image data. Individual shares do not disclose the classified information. The shares are communicated to multiple members over the unguarded network. The integrity of the restructured classified image is an important factor to be considered in VSS. In this research paper, a new Cheating prevention by self-authentication (CPS) is proposed to verify the reconstructed image for its integrity. The proposed method ensures no additional share or third party is involved for its verification. Also, the proposed method works on (n , n) VSS scheme and supports color classified image. [ABSTRACT FROM AUTHOR]

In recent years, online learning has received more attention than ever before. One of the most challenging aspects of online education is the students' assessment since academic integrity could be violated due to various cheating behaviors in online examinations. Although a considerable number of literature reviews exist about online learning, there is no such review study to provide comprehensive insight into cheating motivations, cheating types, cheating detection, and cheating prevention in the online setting. The current study is a review of 58 publications about online cheating, published from January 2010 to February 2021. We present the categorization of the research and show topic trends in the field of online exam cheating. The study can be a valuable reference for educators and researchers working in the field of online learning to obtain a comprehensive view of cheating mitigation, detection, and prevention. [ABSTRACT FROM AUTHOR]

Online exams have become a common tool in the academic didactic process, as well as in most online courses in business. Taking exams in a remote location like home, using ICT tools, brings many challenges to both sides, the learner and the examiner. The aim of this article is to show the challenges in the context of ethical attitudes, trust, and respect for one another. Some results of a broader survey in the form of Computer Aided Web Interviews are presented to highlight students’ opinions and expectations, along with the results of personal interviews with academic teachers. In the final part of the article, recommendations are given. The importance of trust and systematic assessment of learners’ progress is emphasized.

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A concern that has been raised with the transition from pen and paper examinations to electronic examinations is whether this will make cheating easier. This article investigates how teachers and students perceive the differences in ease of cheating during three types of written examination: paper exams, bring your own device e-exams and e-exams using university-owned devices. It also investigates perceptions about the effectiveness of some typical countermeasures towards cheating across these examination types. A mixed-method approach was used, combining questionnaires and interviews with students and teachers in the authors' own university. A total of 212 students and 162 teachers participated in the questionnaire survey, and then, a more limited number were interviewed to get a deeper understanding of the results. Six-different cheating practices were considered – impersonation, forbidden aids, peeking, peer collaboration, outside assistance and student–staff collusion and seven different countermeasures were considered – proctors, biometry, mingling, shuffling, random drawing, sequencing and broadcasting. Both students and teachers perceived cheating as easier with e-exams, and especially with bring your own device. They also thought some countermeasures would be easier to implement with e-exams. [ABSTRACT FROM AUTHOR]

Visual secret sharing (VSS) has various applications such as visual authentication, access control, steganography, watermarking etc. But there is a possibility of cheating or collusive attack in VSS, where some malicious participants can mislead other honest participants by fake shares. Many research groups have worked on the above-stated problem. All the existed techniques suffer from at least one of the following problems such as additional verification shares, pixel expansion and poor visual quality of a reconstructed secret image. The proposed scheme overcomes all the above discussed shortcomings. Proposed work is based on the hamming code. Moreover, it retains the originality of bit by correcting the modified bit. The novelty of the proposed work is to convert the fake/modified shares into the original shares with 100% accuracy. The theoretical and experimental analysis shows the effectiveness of the proposed work. [ABSTRACT FROM AUTHOR]

Online exams have become a common tool in the academic didactic process, as well as in most online courses in business. Taking exams in a remote location like home, using ICT tools, brings many challenges to both sides, the learner and the examiner. The aim of this article is to show the challenges in the context of ethical attitudes, trust, and respect for one another. Some results of a broader survey in the form of Computer Aided Web Interviews are presented to highlight students' opinions and expectations, along with the results of personal interviews with academic teachers. In the final part of the article, recommendations are given. The importance of trust and systematic assessment of learners' progress is emphasized. [ABSTRACT FROM AUTHOR]

As an essential mode of communication, oral presentation plays an important role in the development of second language (L2) automaticity. However, unless best practices are carried out-massive meaningful practice, when presenting seldom relying on the script, in conversational style, and keeping meaningful eye contact with the audience-oral presentation will not be impactful. This paper discusses through a progressive action research in two Chinese as a second language (CSL) classes how using duo devices with video call Apps including WeChat group video call, FaceTime, and Google Duo can successfully help instructors to prevent cheating during oral presentation and thus uphold best practices. [ABSTRACT FROM AUTHOR]

Visual secret sharing (VSS) technology encodes a secret image into some share images for sharing some classified information. Only when the participants gather and stack their share pictures the secret image would be reconstructed and recognizable by the human visual system. Two well-known encoding ways of VSS, visual cryptography (VC) and random grid (RG), have been developed in recent years. As both VC and RG have been considered as a secure way for communicating with high security, they have been pointed out with cheating problems. In this paper, we propose two RG-based VSS schemes with fraud prevention for the cases of (2,n) and (k,n). The experimental results and the analysis of security and contrast show that the proposed method is efficient and practical. [ABSTRACT FROM AUTHOR]

Highlights • Redefine the verification condition in (k, n)-MCPVCS. • Define a minimum (k, n)-connected graph problem. • Propose a (k , n)-MCPVCS with large size of verification image based on 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. [ABSTRACT FROM AUTHOR]

In this paper, a new (k,n) verifiable secret image sharing scheme (VSISS) is proposed in which third order LFSR (linear-feedback shift register)-based public key cryptosystem is applied for the cheating prevention and preview before decryption. In the proposed scheme the secret image is first partitioned into several non-overlapping blocks of k pixels. Every k pixel is then used to form m=⌈k/4⌉+1 pixels of one encrypted share. The original secret image can be reconstructed by gathering any k or more encrypted shared images. The experimental results show that the proposed VSISS is an efficient and safe method.

Test security is not an end in itself; it is important because we want to be able to make valid interpretations from test scores. In this article, I propose a framework for comprehensive test security systems: prevention, detection, investigation, and resolution. The article discusses threats to test security, roles and responsibilities, rigorous training for everyone involved in testing, and an evaluation of current practices in test security. I call on everyone responsible for testing programs-the Association of Test Publishers, Council of Chief State School Officers, National Council on Measurement in Education, U.S. Department of Education, and state assessment program managers, their vendors, and the research community-to collaborate on guidelines and practices for security violation prevention, detection, investigation, and resolution. [ABSTRACT FROM AUTHOR]

This study examines the use frequency by German faculty of 10 different methods for preventing and detecting cheating on exams, plagiarism, and falsification and/or fabrication of data. It also investigates the factors influencing their use. In total, 3655 faculty members from 55 randomly chosen disciplines at 4 German universities were contacted and asked to participate in a web-based survey. Our results show that some methods were applied (very) seldom (e.g. the use of text-matching software), while others were used more frequently (e.g. employing a sufficient number of supervisors for exams). Factors found to promote the increased use of many of these methods include those methods' perceived efficacy as well as external expectations that they be used. When the effort involved in applying a specific method is perceived as high, the frequency of use is reduced. Our results can help universities to improve the prevention and detection of academic dishonesty. [ABSTRACT FROM PUBLISHER]

Secret image sharing (SIS) techniques allow visual secrets to be shared between multiple people. These techniques require a predetermined access structure to be satisfied to reveal the secret. SIS schemes have the potential to increase security in several applications including telemedicine and image transfer in the cloud computing environment, providing controlled access to confidential images. To date, a significant number of SIS schemes with various properties and access structures have been proposed. Among them, hierarchical SIS (HSIS) is considered foremost since almost all organizations and associations manage their secret information in a hierarchical manner. However, the HSIS scheme tends to suffer from security flaws as the secret image can often be visually leaked, even when the access structure is not properly satisfied. To avoid this security flaw, we propose a cheating prevention mechanism by introducing a robust watermarking technique based on the Quantization Index Modulation-Dither Modulation (QIM-DM) algorithm in the discrete cosine transform (DCT) domain. Experimental results demonstrate the superior effectiveness of our proposed cheating prevention mechanism. Furthermore, our approach retains all of the desirable properties of the HSIS scheme. [ABSTRACT FROM AUTHOR]

In this paper, a new ( k , n ) verifiable secret image sharing scheme (VSISS) is proposed in which third order LFSR (linear-feedback shift register)-based public key cryptosystem is applied for the cheating prevention and preview before decryption. In the proposed scheme the secret image is first partitioned into several non-overlapping blocks of k pixels. Every k pixel is then used to form m = ⌈ k / 4 ⌉ + 1 pixels of one encrypted share. The original secret image can be reconstructed by gathering any k or more encrypted shared images. The experimental results show that the proposed VSISS is an efficient and safe method. [ABSTRACT FROM AUTHOR]

Visual secret sharing, or the so-called visual cryptography, is a well-known scheme that encrypts a secret image into several meaningless share images, usually printed on transparencies, and decrypts as stacking some or all share images by the human visual system. More and more researches about visual secret sharing and its applications have been recently proposed. Unfortunately, the cheating attack in which malicious participants cheat the honest one(s) by forging a fake share image has existed. Since 2006, some cheating prevention schemes have been proposed but suffered from one or more disadvantages as follows: (1) maintaining extra share images used to verify the integrity of a share image prior to stacking, (2) introducing extra pixel expansion, (3) raising heavy computation cost, and (4) giving ambiguous cheating detection. In this paper, a multi-factor cheating–preventing scheme, aiming at exploiting the hybrid codebook to hide the additional verification images into the share images, has been proposed without suffering the above-mentioned deficiencies. Two-factor cheating–detection exploits the design of verification to both share images and stacked results to deter attackers’ cheating. The experimental results demonstrate the proposed scheme is feasible. [ABSTRACT FROM AUTHOR]

This paper focuses on a single aspect of learning management systems, i.e. knowledge assessment. The developed web application enables simple knowledge testing by providing the means for creating exam questions carefully. Questions used are MCSA--multiple choice, single answer. Guidelines for creating these questions are presented, while some additional well-established and reputable practices in education such as instant feedback (error and correct answer display) are implemented. The application differentiates between groups of users such as students and teachers, each with its own rights and obligations. Special attention is given to cheating prevention and application abuse. Both functionality of the application and user satisfaction were tested. The results obtained imply the need for this kind of tool in education. [ABSTRACT FROM AUTHOR]

Highlights: [•] Motivation, principle and realization details of a color transfer visual cryptography model. [•] A systematic introduction for visual cryptography design and applications. [•] Extensive experiments for testing the effectiveness and efficiency. [•] Applications in monochrome output devices and low cost display products are tested. [•] Incorporating the extra ability of color transfer into visual cryptography. [Copyright &y& Elsevier]

Visual Cryptography (VC), proposed by Naor and Shamir in 1994, is a variation of the conventional secret sharing scheme. In VC, instead of a numerical secret key, a secret image is shared among participants in the form of images called shares. Each participant possesses his own share which cannot reveal the secret image being alone, making it necessary to stack more than one share of a qualified participant in order to reveal the secret image. Thus in VC the stacking of shares is equivalent to the decryption process, where neither extra computations nor previous knowledge are required to reveal the secret image. Until now some important VC schemes, such as the (k,n)-VC scheme, the general access structure for VC and the extended VC (EVC), have been proposed. Unfortunately all schemes can be cheated, if one or more participants try to generate their fake shares to force the revealed secret image to be a faked one. In this paper, we propose a cheating prevention VC scheme, in which the shares can be identified and authenticated using the EVC scheme and watermarking techniques. In the proposed VC scheme, the share of each participant can be identified by its meaningful appearance instead of noise-like image used in the conventional VC scheme. For the purpose of authentication of each share two binary watermark images are encrypted using shift operation. Before the secret image is revealed, the validation of the shares must be carried out, extracting two watermark images. If they can be extracted correctly, the revealed secret image is considered as authentic; otherwise it is determined as a faked one. The simulation results show the desirable performance of the proposed EVC scheme.

In visual cryptography (VC), cheating is an important security concern where dishonest participants will fool honest ones and make them accept a fake secret by providing fake shares. Share and blind authentications are two categories of cheating prevention, and the last one relies on the inherent robust of shares against cheating attacks. In the previous studies, cheating in VC only focuses on operating a 'pixel block' instead of a region of adjacent pixels. However, the well-known advantage of VC is to decode the secret image by using the human vision system (HVS), so it leads to a natural issue to reconsider cheating a region. In this paper, we formally address the binocular cheating attack (BCA) for a region to augment effectiveness of original cheating for a block. Finally, we demonstrate how to realize BCA by presenting non-trivial techniques against some blind authentication schemes, and further obtain implausible results. The BCA can also be applied to halftone secret. [ABSTRACT FROM AUTHOR]

Abstract: Visual cryptography (VC), first presented by Naor and Shamir, is a variant of secret sharing, thus it also called visual secret sharing. It can be widely used in many applications such as encrypting large data efficiently. In the literature, the problem of cheating is under consideration in secret sharing. Recently, Horng et al. pointed out that cheating is possible in k-out-of-n VC schemes, and presented two kinds of the cheating prevention schemes for protecting honest participants. One of them is the authentication based cheating prevention scheme. In this paper, we analyze the definition of cheating prevention and propose a new authentication based cheating prevention scheme. This scheme is constructed with Naor–Shamir’s VC scheme. Finally, we give the security analysis to prove that the proposed scheme is immune to cheating. [Copyright &y& Elsevier]

Visual Cryptography (VC), proposed by Naor and Shamir in 1994, is a variation of the conventional secret sharing scheme. In VC, instead of a numerical secret key, a secret image is shared among participants in the form of images called shares. Each participant possesses his own share which cannot reveal the secret image being alone, making it necessary to stack more than one share of a qualified participant in order to reveal the secret image. Thus in VC the stacking of shares is equivalent to the decryption process, where neither extra computations nor previous knowledge are required to reveal the secret image. Until now some important VC schemes, such as the (k,n)-VC scheme, the general access structure for VC and the extended VC (EVC), have been proposed. Unfortunately all schemes can be cheated, if one or more participants try to generate their fake shares to force the revealed secret image to be a faked one. In this paper, we propose a cheating prevention VC scheme, in which the shares can be identified and authenticated using the EVC scheme and watermarking techniques. In the proposed VC scheme, the share of each participant can be identified by its meaningful appearance instead of noise-like image used in the conventional VC scheme. For the purpose of authentication of each share two binary watermark images are encrypted using shift operation. Before the secret image is revealed, the validation of the shares must be carried out, extracting two watermark images. If they can be extracted correctly, the revealed secret image is considered as authentic; otherwise it is determined as a faked one. The simulation results show the desirable performance of the proposed EVC scheme. [ABSTRACT FROM AUTHOR]

The paper addresses the cheating prevention in secret sharing. We consider secret sharing with binary shares. The secret also is binary. This model allows us to use results and constructions from the well developed theory of cryptographically strong boolean functions. In particular, we prove that for given secret sharing, the average cheating probability over all cheating vectors and all original vectors, i.e., 1/n 2^n ∑ _c=1...n ∑ _α ∈V n ρ _c,α , denoted by øverlineρ , satisfies øverlineρ ≥ \frac12 , and the equality holds if and only if ρ _c,α satisfies ρ _c,α = \frac12 for every cheating vector δ _c and every original vector α . In this case the secret sharing is said to be cheating immune. We further establish a relationship between cheating-immune secret sharing and cryptographic criteria of boolean functions.This enables us to construct cheating-immune secret sharing.

Abstract: In 1995, Naor and Shamir proposed the k-out-of-n visual cryptography scheme such that only more than or equal to k participants can visually recover the secret through superimposing their transparencies. Visual cryptography schemes have been extensively investigated since their invention and extended to numerous applications such as visual authentication and identification, steganography, and image encryption. In 2006, Horng et al. proposed that cheating is possible where some participants can deceive the remaining participants by delivering forged transparencies. Meanwhile, Horng et al. also proposed two cheating prevention schemes. One scheme, however, requires extra verification transparencies and the other needs larger transparencies. In other words, compared to visual cryptography, both schemes burden each participant with an additional problem of transparency management. In this paper, a more secure scheme is given to solve the cheating problem without extra burdens by adopting multiple distinct secret images. Moreover, for sharing these secret images simultaneously, the share construction method of visual cryptography is redesigned and extended by generic algorithms. Finally, the results of the experiment and security analysis show that not only the proposed scheme is more secure in comparison with the two previous cheating prevention schemes in the literature, but extra burdens are also eliminated. [Copyright &y& Elsevier]

The paper addresses the cheating prevention in secret sharing. We consider secret sharing with binary shares. The secret also is binary. This model allows us to use results and constructions from the well developed theory of cryptographically strong boolean functions. In particular, we prove that for given secret sharing, the average cheating probability over all cheating vectors and all original vectors, i.e., …, denoted by ρ, satisfies ρ ≥ ½, and the equality holds if and only if ρc,α satisfies ρc,α = ½ for every cheating vector dc and every original vector α. In this case the secret sharing is said to be cheating immune. We further establish a relationship between cheating-immune secret sharing and cryptographic criteria of boolean functions. This enables us to construct cheating-immune secret sharing. [ABSTRACT FROM AUTHOR]