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Internet applications rely on Secure Socket Layer (SSL)/Transport Security Layer (TSL) certifications to establish secure communication. However, the centralized nature of certificate authorities (CAs) poses a risk, as malicious third parties could exploit the CA to issue fake certificates to malicious web servers, potentially compromising the privacy and integrity of user data. In this paper, we demonstrate how the utilization of decentralized certificate verification with blockchain technology can effectively address and mitigate such attacks. We present a decentralized public key infrastructure (PKI) based on a distributed trust model, e.g., Web of Trust (WoT) and blockchain technologies, to overcome vulnerabilities like single points of failure and to prevent tampering with existing certificates. In addition, our infrastructure establishes a trusted key-ring network that decouples the authentication process from CAs in order to enhance secure certificate issuance and accelerate the revocation process. Furthermore, as a proof of concept, we present the implementation of our proposed system in the Ethereum blockchain, confirming that the proposed framework meets the five identified requirements. Our experimental results demonstrate the effectiveness of our proposed system in practice, albeit with additional overhead compared to conventional PKIs. [ABSTRACT FROM AUTHOR]

ABSTRACT One of the critical yet lingering issues in computer security is insider threat, and it often takes advantage of some security services based on directory services such as authentication and access control. Detecting these threats is quite challenging because malicious users with the technical ability to leverage these services often have sufficient knowledge and expertise to conceal unauthorized activity. In this article, we present an approach using directory virtualization to monitor various systems across an enterprise for the purpose of detecting malicious insider activity. Specifically, a policy engine that leverages directory virtualization services is proposed to enhance monitoring and detecting capabilities by allowing greater flexibility in analyzing changes for malicious intent. The resulting architecture is a system-based approach, where the relationships and dependencies between data sources and directory services are used to detect an insider threat, rather than simply relying on point solutions. This paper presents such an architecture in detail, including a description of implementation results. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Dual supply voltage design is widely accepted as an effective way to reduce the power consumption of CMOS circuits. In this paper, we propose a comprehensive design framework that includes dual-Vdd scheduling, dual-Vdd allocation, controller synthesis as well as layout generation. In particular, we address a problem of high-level synthesis with objective of minimizing power consumption of storage units and multiplexers using dual-Vdd; this is made possible by utilizing timing slack that is left in the data-path after operation scheduling. We use integer linear programming (ILP) and also provide heuristic algorithms to solve the dual-Vdd register and connection allocation. The physical layout of dual-Vdd circuits has to separate power rails of Vddh and Vddl cells from each other. We propose a voltage island based placement algorithm to relieve this restriction and allow more flexibility of placement. In experiments on benchmark designs implemented in 1.08 V (with Vddl of 0.8 V) 65-nm CMOS technology, both switching and leakage power are reduced by 20% on average, respectively, compared to data-path with dual-Vdd applied to functional units alone. Detailed analysis of area and wirelength is performed to assess feasibility of the proposed method. [ABSTRACT FROM AUTHOR]

Entropy-based goodness-of-fit test statistics can be established by estimating the entropy difference or Kullback–Leibler information, and several entropy-based test statistics based on various entropy estimators have been proposed. In this article, we first give comments on some problems resulting from not satisfying the moment constraints. We then study the choice of the entropy estimator by noting the reason why a test based on a better entropy estimator does not necessarily provide better powers. [ABSTRACT FROM AUTHOR]

A Bayesian approach is considered for identifying sources of nonstationarity for models with a unit root and breaks. Different types of multiple breaks are allowed through crash models, changing growth models, and mixed models. All possible nonstationary models are represented by combinations of zero or nonzero parameters associated with time trends, dummy for breaks, or previous levels, for which Bayesian posterior probabilities are computed. Multiple tests based on Markov chain Monte Carlo procedures are implemented. The proposed method is applied to a real data set, the Korean GDP data set, showing a strong evidence for two breaks rather than the usual unit root or one break. [ABSTRACT FROM AUTHOR]

For panel models of cross-sectionally correlated time series, seasonal unit root tests are constructed for each seasonal frequency. The tests are based on instrumental variable estimators which are modifications of signs of the regressors. Cross-sectional correlation is controlled by rotating the system of time series using an estimated error covariance matrix. The limiting null distributions of the tests are chi-squared and are free from nuisance parameters arising from cross-sectional correlation. A Monte-Carlo experiment compares size and power performances of the proposed tests. [ABSTRACT FROM AUTHOR]

This paper proposes various double unit root tests for cross-sectionally dependent panel data. The cross-sectional correlation is handled by the projection method [P.C.B. Phillips and D. Sul, Dynamic panel estimation and homogeneity testing under cross section dependence, Econom. J. 6 (2003), pp. 217-259; H.R. Moon and B. Perron, Testing for a unit root in panels with dynamic factors, J. Econom. 122 (2004), pp. 81-126] or the subtraction method [J. Bai and S. Ng, A PANIC attack on unit roots and cointegration, Econometrica 72 (2004), pp. 1127-1177]. Pooling or averaging is applied to combine results from different panel units. Also, to estimate autoregressive parameters the ordinary least squares estimation [D.P. Hasza and W.A. Fuller, Estimation for autoregressive processes with unit roots, Ann. Stat. 7 (1979), pp. 1106-1120] or the symmetric estimation [D.L. Sen and D.A. Dickey, Symmetric test for second differencing in univariate time series, J. Bus. Econ. Stat. 5 (1987), pp. 463-473] are used, and to adjust mean functions the ordinary mean adjustment or the recursive mean adjustment are used. Combinations of different methods in defactoring to eliminate the cross-sectional dependency, integrating results from panel units, estimating the parameters, and adjusting mean functions yields various available tests for double unit roots in panel data. Simple asymptotic distributions of the proposed test statistics are derived, which can be used to find critical values of the test statistics. We perform a Monte Carlo experiment to compare the performance of these tests and to suggest optimal tests for a given panel data. Application of the proposed tests to a real data, the yearly export panel data sets of several Latin-American countries for the past 50 years, illustrates the usefulness of the proposed tests for panel data, in that they reveal stronger evidence of double unit roots than the componentwise double unit root tests of Hasza and Fuller [Estimation for autoregressive processes with unit roots, Ann. Stat. 7 (1979), pp. 1106-1120] or Sen and Dickey [Symmetric test for second differencing in univariate time series, J. Bus. Econ. Stat. 5 (1987), pp. 463-473]. [ABSTRACT FROM AUTHOR]

With growing market pressures and rising system complexities, automated system-level communication design with efficient design space exploration capabilities is becoming increasingly important. At the same time, customized network-oriented communication architectures become necessary in enabling a high-performance communication among the system components. To this end, corresponding communication design flows that are supported by efficient design automation techniques need to be developed. In this paper, we present a system-level design environment for the generation of bus-based system-on-chip architectures. Our approach supports a two-stage design flow using automated model refinement toward custom heterogeneous communication networks. Starting from an abstract specification of the desired communication channels, our environment automatically generates tailored network models at various levels of abstraction. At its core, an automatic layer-based refinement approach is utilized. We have applied our approach to a set of industrial-strength examples with a wide range of target architectures. Our experimental results show significant productivity gains over a traditional communication design, allowing early and rapid design space exploration. [ABSTRACT FROM AUTHOR]

Bayesian analysis of panel data using a class of momentum threshold autoregressive (MTAR) models is considered. Posterior estimation of parameters of the MTAR models is done by using a simple Markov Chain Monte Carlo (MCMC) algorithm. Selection of appropriate differenced variables, test for asymmetry and unit roots are recast as model selections and a simple way of computing posterior probabilities of the candidate models is proposed. The proposed method is applied to the yearly unemployment rates of 51 US states and the results show strong evidence of stationarity and asymmetry. [ABSTRACT FROM AUTHOR]

Over the last decade there has been a tremendous advance in the theory and practice of role-based access control (RBAC). One of the most significant aspects of RBAC can be viewed from its management of permissions on the basis of roles rather than individual users. Consequently, it reduces administrative costs and potential errors. The management of roles in various RBAC implementations, however, tends to be conducted on an ad hoc basis, closely coupled with a certain context of system environments. This paper discusses the development of a system whose purpose is to help manage a valid set of roles with assigned users and permissions for role-based authorization infrastructures. We have designed and implemented the system, called RolePartner. This system enables role administrators to build and configure various components of a RBAC model so as to embody organizational access control policies which can be separated from different enforcement mechanisms. Hence the system helps make it possible to lay a foundation for role-based authorization infrastructures. Three methodological constituents are introduced for our purposes, together with the design and implementation issues. The system has a role-centric view for easily managing constrained and hierarchical roles as well as assigned users and permissions. An LDAP-accessible directory service was used for a role database. We show that the system can be seamlessly integrated with an existing privilege-based authorization infrastructure. Copyright © 2004 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

An introduction to the journals is presented in which the editor discusses various reports within the issue on topics including malware and other undesirable Android applications or apps, users' geographic location privacy, and the broad challenge of bring your own device (BYOD).