Qualified Sets Research Articles

Conjunctive hierarchical secret sharing by finite geometry

AbstractSecret sharing is a general method for distributing sensitive data among the participants of a system such that only a collection of predefined qualified coalitions can recover the secret data. One of the most widely used special cases is threshold secret sharing, where every subset of participants of size above a given number is qualified. In this short note, we propose a general construction for a generalized threshold scheme, called conjunctive hierarchical secret sharing, where the participants are divided into disjoint levels of hierarchy, and there are different thresholds for all levels, all of which must be satisfied by qualified sets. The construction is the first method for arbitrary parameters based on finite geometry arguments and yields an improvement in the size of the underlying finite field in contrast with the existing results using polynomials.

Weighted visual secret sharing for general access structures based on random grids

The traditional visual secret sharing (VSS) schemes share a secret image into multiple shares, and all the shares have the same importance. However, it is occasionally necessary to differentiate participants based on their different levels of importance in certain applications. In previous works, some weighted VSS schemes were implemented only for the (k,n) threshold access structure and were not applicable to other access structures. In this paper, a weighted VSS scheme is proposed for general access structures (GAS) based on random grids (RG). For the different qualified sets of shares, the amount of information we get about the secret image is different because the total weight of the shares participating in the recovery process is different. Moreover, both OR and XOR operations can be applied to recover the secret image, which can extend the applications of our scheme. For the same minimal qualified set, we can obtain better visual quality by stacking (XOR-ing) more shares. In addition, we can obtain the lossless secret image by performing the XOR operation on all shares. More importantly, our scheme is suitable for GAS; however, it has certain limitations in the weight assignment of participants for the non-threshold access structures. Finally, experiments and comparisons demonstrate the effectiveness of our scheme.

A Novel ( t , s , k , n )-Threshold Visual Secret Sharing Scheme Based on Access Structure Partition

Visual secret sharing (VSS) is a new technique for sharing a binary image into multiple shadows. For VSS, the original image can be reconstructed from the shadows in any qualified set, but cannot be reconstructed from those in any forbidden set. In most traditional VSS schemes, the shadows held by participants have the same importance. However, in practice, a certain number of shadows are given a higher importance due to the privileges of their owners. In this article, a novel ( t , s , k , n )-threshold VSS scheme is proposed based on access structure partition. First, we construct the basis matrix of the proposed ( t , s , k , n )-threshold VSS scheme by utilizing a new access structure partition method and sub-access structure merging method. Then, the secret image is shared by the basis matrix as n shadows, which are divided into s essential shadows and n - s non-essential shadows. To reconstruct the secret image, k or more shadows should be collected, which include at least t essential shadows; otherwise, no information about the secret image can be obtained. Compared with related schemes, our scheme achieves a smaller shadow size and a higher visual quality of the reconstructed image. Theoretical analysis and experiments indicate the effectiveness of the proposed scheme.

(t, k, n) XOR-based visual cryptography scheme with essential shadows

Visual cryptography scheme (VCS) shares a binary secret image into multiple shadows, only qualified set of shadows can reveal the secret image by stacking operation. However, VCS suffers the problems of low visual quality of the revealed image and large shadow size. A (t, k, n) XOR-based visual cryptography scheme (XVCS) shares the secret image into n shadows including t essentials and n-t non-essentials. A qualified set of shadows contains any k shadows including t essentials. The revealing process is implemented by XOR operation on the involved shadows. In this paper, we propose a construction method for (t, k, n)-XVCS with essential shadows. The secret image can be revealed perfectly, and the shadow size is small compared with VCS. Theoretical analysis and experimental results show the security and effectiveness of the proposed scheme.

Classical access structures of ramp secret sharing based on quantum stabilizer codes

In this paper, we consider to use the quantum stabilizer codes as secret sharing schemes for classical secrets. We give necessary and sufficient conditions for qualified and forbidden sets in terms of quantum stabilizers. Then, we give a Gilbert–Varshamov-type sufficient condition for existence of secret sharing schemes with given parameters, and by using that sufficient condition, we show that roughly 19% of participants can be made forbidden independently of the size of classical secret, in particular when an n-bit classical secret is shared among n participants having 1-qubit share each. We also consider how much information is obtained by an intermediate set and express that amount of information in terms of quantum stabilizers. All the results are stated in terms of linear spaces over finite fields associated with the quantum stabilizers.

Visual cryptography scheme on graphs with $m^{*}(G)=4$

‎Let $G=(V,E)$ be a connected graph and $Gamma (G)$ be the strong access structure where obtained from graph $G$‎. ‎A visual cryptography scheme (VCS) for a set $P$ of participants is a method to encode a secret image such that any pixel of this image change to $m$ subpixels and only qualified sets can recover the secret image by stacking their shares‎. ‎The value of $m$ is called the pixel expansion and the minimum value of the pixel expansion of a VCS for $Gamma (G)$ is denoted by $m^{*}(G)$‎. ‎In this paper we obtain a characterization of all connected graphs $G$ with $m^{*}(G)=4$ and $omega (G)=5$ which $omega(G)$ is the clique number of graph $G$‎.

Generalized general access structure in secret image sharing

Generally speaking, the probability of every qualified set is the same and fixed in conventional secret image sharing (SIS) for general access structure (GAS). In this paper, first we introduce generalized GAS (GGAS), which allows the user to assign probability to every qualified set. Then we design a SIS scheme for GGAS by Chinese remainder theorem (CRT). On one hand, for any qualified set, we can decode the secret image at pre-assigned probability. When we collect all the shares, we can losslessly decode the secret image. On the other hand, for any forbidden set, we will decode nothing of the secret image. We only employ modular operation to decode the secret image, which may be suitable for real-time and green computing scenarios. Experimental results and analyses are realized to examine the effectiveness of our scheme.

A Probabilistic Model for Finding an Optimal Host Framework and Load Distribution in Cloud Environment

Cloud Computing is being widely accepted in this computing world and comprises of many hardware and software resources. It becomes critical to meet their client’s needs on time if the cloud data centers are so overloaded. In this regard, if the utilization of resources becomes an intelligent way so that we focused on the selection problem of the physical hosts for deploying the tasks. So, OPH-LB (Optimal Physical Host with effective Load Balancing) framework is proposed to model the service of client’s requests in this IaaS architecture with heterogeneous virtual machines. It proposes the thought of accomplishing load balancing in this dynamic environment. Firstly, this OPH-LB approach is filtering the qualified hosts among all which accomplishes the requirement of deploying tasks. Then out of those qualified sets, we apply probablistic model which helps to find the most optimal host in terms of its computing capability and its performance function. Further, the performance is analyzed using Cloudsim simulation tool and compared with existing approaches. The results demonstrate that our model has improved the throughput, reduced the failure rate and optimized the attainment of cloud data centers.

Progressive visual secret sharing for general access structure with multiple decryptions

Visual secret sharing (VSS) for general access structure (GAS) owns wider applications than (k, n) threshold VSS. VSS with multiple decryptions realizes the functionalities of both OR-based VSS (OVSS) and XOR-based VSS (XVSS), which can broaden the applications as well compared to one recovery method-based VSS. In this paper, we propose a progressive VSS (PVSS) scheme for GAS with the features of both OR and XOR decryptions based on random grid (RG). The different regions of the secret image and corresponding genearted random bits are employed to gain progressive property as well as GAS with OR and XOR decryptions. For the qualified sets, if we have a copy machine, we can reconstruct the secret by stacking. On the other hand, if a device with XOR operation is available, we can improve the visual quality of the recovered secret image as well as we can reconstruct the secret image losslessly when we collect all the n shares. In addition, our scheme has neither pixel expansion nor codebook design due to RG. The effectiveness of the proposed scheme are shown in terms of experimental results and analyses.

Vínculos diferentes para o mesmo trabalho: comprometimento organizacional dos trabalhadores da empresa e trabalhadores temporários

In the contexts of recommending organizational flexibility, companies are increasingly turning to temporary work as a competitive strategy. Temporary work is presupposed in Atkinson's (1987) flexible enterprise design, which advocates the segmentation of the workforce into two distinct groups: nuclear workers and peripheral workers. Nuclear workers, being crucial to the core business of the organization, would have access to job stability, training and development. Peripheral workers would be hired according to firms' specific needs for non-nuclear activities, allowing a reduction of fixed costs and administrative burden with human resources (De Cuyper and De Witte, 2008; Nollen, 1996). In industry, temporary work has allowed companies to maintain a less qualified set of workers, using numerical flexibility, which ensures production at lower costs and at times of market oscillation (Garcia-Perez and Munoz-Bullon, 2005). Notwithstanding the advantages advocated, the use of temporary work has presented some limitations, namely the high level of absenteeism of temporary workers, their discontent with different treatment, precariousness and lack of training (Booth, 2002; Nollen, 1996) . This discontent depends on the socio-occupational profiles of the workers, and there are cases where they do not occur (Chambel, 2006). Within this framework, and considering the organizational commitment, generically as the identification of the worker with the company, the will to remain and continue in the company and to get involved and to strive to achieve the objectives of the company (Meyer and Allen, 1997), the present The objective of this study is to analyze the commitment of temporary workers (TT) and the company (TE) of an industrial company. Having as specific objectives: 1) To identify the levels of organizational commitment of TT and TE in the three components; 2) To understand the relationship between the levels of organizational commitment of TT and TE; 3) Understand the correlation of commitment with age and seniority. From a methodological point of view, the questionnaire survey developed by Meyer and Allen (1991), validated for the Portuguese population by Nascimento, Lopes and Salgueiro (2008) was applied. The same considers three components of commitment: affective; normative; calculative The survey was applied to a convenience sample of 85 workers: 59 temporary workers (TT) and 26 employees of the company (TE). All workers had low levels of literacy (2nd cycle) and qualification and belonged to the operational center. Data were analyzed through SPSS, version 21, using descriptive statistical analysis and correlations. The main results were as follows: 1) affective commitment is the one that obtained the highest overall average; 2) TTs present a calculative impairment with the highest mean result and ETs present an affective compromise with the highest mean result; 3) there was a strong correlation between affective and normative impairment and between normative and calculative impairment and a weaker correlation between affective and calculative impairment; 4) in TT, there were negative correlations between the three levels of organizational commitment and seniority, while in the ET there was no correlation between organizational commitment and seniority; 6) in TT there is a weak correlation between impairment and age, while in ET there was a strong and positive correlation between affective and normative impairment and age.

Optimal Improvement Ratios of Multi-Secret Sharing Schemes Can Be Achieved

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 .

Standardized Consolidated Calculated and Reference Experimental Database (SCCRED): A Supporting Tool for V&V and Uncertainty Evaluation of Best-Estimate System Codes for Licensing Applications

This paper discusses the role and the depth of the analysis required for merging, on one hand, suitable experimental data and, on the other hand, qualified code calculation results. The availability of an experimental and calculated qualified database is of utmost importance for the validation and qualification of codes. Such a database can be used not only for demonstrating that the code results are reliable and for performing an independent code assessment but also as a basis for developing and validating an uncertainty methodology. As discussed in several other papers and guidelines, an uncertainty methodology must rely on the availability of a qualified code and qualified procedures. The development of a Standardized Consolidated Calculated and Reference Experimental Database (SCCRED) that includes documentation such as the reference data set of the facility and of the tests, the qualification report of the code calculations, and the engineering handbook constitutes an approach envisaged also by the International Atomic Energy Agency to set up a qualified experimental and calculated database for verification and validation (V&V) purposes of computational tools and uncertainty methodologies.In order to frame and to outline the role of a qualified database for performing a best-estimate and uncertainty analysis (UA), a summary of the approaches for performing the uncertainty evaluation is provided distinguishing among the methods based on propagation of input uncertainties, the methods based on code output accuracy propagation, and the predictive modeling methodology. The main issues from the review of the uncertainty methods are the following: (a) the identification of the uncertainty-method-user effect to be considered in addition to the more well-known code-user effect when the BEPU (Best Estimate Plus Uncertainty) approach is selected to perform accident analysis and (b) (partially connected also with the first issue) the need for validation of the uncertainty methods (in the same way as validation of a computer code is a fundamental prerequisite for application of the code).To address the two issues above, the Code with the capability of Internal Assessment of Uncertainty (CIAU) is discussed in detail. In particular, it shall be noted that the CIAU method (which belongs to the methods based on code output accuracy propagation) needs a qualified set of experimental and code calculation results as input for performing a qualified intrinsically validated UA, which has a more limited uncertainty-method-user effect in comparison to the methods based on propagation of input uncertainties. Following the above consideration, the creation of SCCRED as a standardized consolidated reference experimental and calculated database constitutes a prerequisite for the development and application of the CIAU method, but at the same time such a qualified database can also be used for the V&V process of methods based on propagation of input uncertainties contributing to limit the uncertainty-method-user effect.

Visual multiple-secret sharing for flexible general access structure by random grids

For visual secret sharing (VSS), general access structure (GAS), which can freely define the qualified set and the forbidden set, provides dealers the ability to share secret information with the qualified set but not the forbidden set. In previous studies, the proposed GAS schemes have focused on strong GAS, but it has retained restrictions and inconvenience in some secret-sharing scenarios. Recently, the random-grid-based VSS (RG-based VSS) technique has aimed to overcome the problem of pixel expansion from which the visual-cryptography-based VSS (VC-based VSS) techniques usually suffer. This paper presents a flexible GAS VSS scheme by RG that is appropriate for wide use and that serves special cases like (2, n), (n, n), and (k, n). The paper also outlines how the scheme can be extended for multiple secrets. The performance and the security of the scheme are theoretically analyzed.

Secret image sharing with smaller shadow sizes for general access structures

In the area of secret image sharing (SIS), most papers focused on the schemes for threshold or some special access structures. Regarding general access structures (GAS), few results have been found in the literature. Two SIS schemes for GAS were proposed in 2001 and 2010, both are based on qualified sets. However, one distorts the reconstructed secret image, and some extra information is needed in both schemes. Here, we propose three polynomial based SIS schemes for GAS. Considering either qualified or forbidden sets, these schemes can reconstruct the secret image perfectly without any extra information needed. Some proof and analysis on the shadow sizes of the three schemes are given to lead us to choose the one with the smallest size. In addition, we also give some comparisons with two existing schemes, and security issue is also addressed in conclusion.

Coding Theoretic Construction of Quantum Ramp Secret Sharing

We show a construction of a quantum ramp secret sharing scheme from a nested pair of linear codes. Necessary and sufficient conditions for qualified sets and forbidden sets are given in terms of combinatorial properties of nested linear codes. An algebraic geometric construction for quantum secret sharing is also given.

Extended Capabilities for XOR-Based Visual Cryptography

The XOR-based visual cryptography (VC) is a possible methodology to solve the poor visual quality problem without darkening the background in VC. However, investigations on XOR-based VC are not sufficient. In this paper, we exploit some extended capabilities for XOR-based VC. Actually, two XOR-based VC algorithms are proposed, namely XOR-based VC for general access structure (GAS) and adaptive region incrementing XOR-based VC. The first algorithm aims to implement complicated sharing strategy using GAS, while maintaining merits such as perfect reconstruction of secret, no pixel expansion, and no code book requirement. In the second algorithm, the concept of adaptive security level is first introduced, where the security levels are recovered in accordance with the qualified sets instead of the quantity of stacked shares. Adaptive region incrementing XOR-based VC further enriches the application scenarios. Theoretical analysis on the proposed algorithms are provided, as well as extensive experimental results and evaluations for demonstrating the effectiveness and advantages of the two methods.

极小特权数组上的理想多秘密共享方案

How to construct an ideal multi-secret sharing scheme for general access structures is difficult. In this paper, we solve a public problem proposed by Spiez et al. recently [Finite fields and their application, 2011, 17: 329-342], namely to design an algorithm of privileged coalitions of any length if such coalitions exist. Furthermore, in terms of privileged coalitions, we show that most of the existing multi-secret sharing schemes based on Shamir threshold secret sharing are not perfect by analyzing Yang et al.s scheme and Pang et al.s scheme. Finally, based on the algorithm mentioned above, we devise an ideal multi-secret sharing scheme for families of access structures, which possesses more vivid qualified sets than that of the threshold scheme.

A Hybird Virtual Machine Placement Aglrithm for Virtualized Desktop Infrastructure

As we all kown, The virtual machine placement is one kind of bin-packing problem. By optimizing placement of virtual machine. We can improve VM performance, enhance resource utilization, reduce energy comsumption. After analysis the existing virtual machine placement aglrithm. We propose a hybird virtual machine placement aglrithm (HTA) which based on network latency threshold for the requirement of low network latence and low VM migraiton ratio in Virtualized Desktop Infrastructure. It elect qualified node set based on network latency threshold and palce the virtual machines with load-balance policy, taking into account the preformance of the network and vitual machines. According to analysis and comparison. The simulation result show that the algorithm can effectively lessen the network latency and reduce the VM migration ratio.

Visual secret sharing for general access structures by random grids

Visual secret sharing (VSS) is a way to protect a secret image among a group of participants by using the notions of perfect ciphers and secret sharing. However, each share generated by conventional VSS is m times as big as the original secret image, where m is called pixel expansion. Random grid (RG) is an alternative approach to implement VSS without pixel expansion. However, reported RG-based VSS methods are threshold schemes. In this study, RG-based VSS for general access structures is presented. Secret image is encoded into n RGs while qualified sets can recover the secret visually and forbidden sets cannot. The proposed scheme is a generalisation of the threshold methods, where those reported RG-based schemes can be considered as the special cases of the proposed scheme. Experimental results are provided, demonstrating the effectiveness and advantages of the proposed scheme.

RISA: a new web-tool for Rapid Identification of SSRs and Analysis of primers

The simple sequence repeats (SSRs) are short tandem arrayed sequence motifs consisting of 2–6 bp, which are not only involved in causing human fatal diseases but also have various applications in plant genetic studies. Thanks to the advancements made in sequencing technology, now we can easily generate genomic/transcriptomic sequences in a shorter period of time. Therefore, trend to identify SSR markers needs up gradation to handle these high-throughput data. Unfortunately, existing web programs for identifying SSR markers are useful but they are unable to process high-throughput data. To overcome this disadvantage, we have constructed a web-based tool, RISA (http://sol.kribb.re.kr/RISA/), with a goal of one-click service to identify SSR markers from high-throughput data (up to 200 Mbp). RISA controls automatic input and output pipeline by demon which combines the SSR classification and investigation by Robert Kofler (SciRoKo) to search SSRs and Primer3 to identify primers specific to SSRs simultaneously. In our test, 45,495 qualified primer sets specific to 47,070 SSRs were identified by RISA from whole Arabidopsis lyrata genome (about 207 Mbp) in 15 minutes. In results, it includes SSR statistics generated from user’s queries and SSR markers information along with primers suitable for their amplification. To support handling of large amount of results, RISA provides various filtering options such as motif length, repeat units, total length and PCR product size. Therefore, we propose that RISA minimizes labour-intensive works or any other considerations which can be required during the development of SSR markers without having deep understanding of computer system and/or algorithms.