349 resultados para Saïd, Edward


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Shelton, Edward Mason; p.548 Sherwood Arboretum; p.550 Soutter, William; pp.563-564 Styles or gardens and designed landscapes; pp.575-576 Summer-house; pp.579-580 Trapnell, Walter George; p.602 Tropical Gardens; pp.604-605 Wickham Park; p.642 Wijaya, Made; p.642 Williams, George; p.644 Williams, Keith A.W.; p.644 Verandah Garadening; p.614

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Nonlinear filter generators are common components used in the keystream generators for stream ciphers and more recently for authentication mechanisms. They consist of a Linear Feedback Shift Register (LFSR) and a nonlinear Boolean function to mask the linearity of the LFSR output. Properties of the output of a nonlinear filter are not well studied. Anderson noted that the m-tuple output of a nonlinear filter with consecutive taps to the filter function is unevenly distributed. Current designs use taps which are not consecutive. We examine m-tuple outputs from nonlinear filter generators constructed using various LFSRs and Boolean functions for both consecutive and uneven (full positive difference sets where possible) tap positions. The investigation reveals that in both cases, the m-tuple output is not uniform. However, consecutive tap positions result in a more biased distribution than uneven tap positions, with some m-tuples not occurring at all. These biased distributions indicate a potential flaw that could be exploited for cryptanalysis

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This work examines the algebraic cryptanalysis of small scale variants of the LEX-BES. LEX-BES is a stream cipher based on the Advanced Encryption Standard (AES) block cipher. LEX is a generic method proposed for constructing a stream cipher from a block cipher, initially introduced by Biryukov at eSTREAM, the ECRYPT Stream Cipher project in 2005. The Big Encryption System (BES) is a block cipher introduced at CRYPTO 2002 which facilitates the algebraic analysis of the AES block cipher. In this article, experiments were conducted to find solutions of equation systems describing small scale LEX-BES using Gröbner Basis computations. This follows a similar approach to the work by Cid, Murphy and Robshaw at FSE 2005 that investigated algebraic cryptanalysis on small scale variants of the BES. The difference between LEX-BES and BES is that due to the way the keystream is extracted, the number of unknowns in LEX-BES equations is fewer than the number in BES. As far as the authors know, this attempt is the first at creating solvable equation systems for stream ciphers based on the LEX method using Gröbner Basis computations.

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We present several new observations on the SMS4 block cipher, and discuss their cryptographic significance. The crucial observation is the existence of fixed points and also of simple linear relationships between the bits of the input and output words for each component of the round functions for some input words. This implies that the non-linear function T of SMS4 does not appear random and that the linear transformation provides poor diffusion. Furthermore, the branch number of the linear transformation in the key scheduling algorithm is shown to be less than optimal. The main security implication of these observations is that the round function is not always non-linear. Due to this linearity, it is possible to reduce the number of effective rounds of SMS4 by four. We also investigate the susceptibility of SMS4 to further cryptanalysis. Finally, we demonstrate a successful differential attack on a slightly modified variant of SMS4. These findings raise serious questions on the security provided by SMS4.

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In the UK, Singapore, Canada, New Zealand and Australia, as in many other jurisdictions, charity law is rooted in the common law and anchored on the Statute of Charitable Uses 1601. The Pemsel classification of charitable purposes was uniformly accepted, and together with a shared and growing pool of judicial precedents, aided by the ‘spirit and intendment’ rule, has subsequently allowed the law to develop along much the same lines. In recent years, all the above jurisdictions have embarked on law reform processes designed to strengthen regulatory processes and to statutorily define and encode common law concepts. The reform outcomes are now to be found in a batch of national charity statutes which reflect interesting differences in the extent to which their respective governments have been prepared to balance the modernising of charitable purposes and other common law concepts alongside the customary concern to tighten the regulatory framework.

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The Preamble1 was the initial legislative statement of matters construed by government to constitute charitable purposes in a common law context. It provided an outline of what was to become the core agenda for government’s relationship with charity. The resulting implied partnership, as viewed by government, endured for four centuries and in many different cultural contexts across the common law world. During that period, judicial mediation on the balance to be struck between government interest in acquiring value for granting tax exempt privileges and the right of individuals to freely dispose of property in accordance with their particular altruistic wishes steadily broadened the range of purposes deemed to be charitable, the vagaries of donor choice often prevailing over government interest in acquiring value for tax exemption.

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This chapter addresses the question, how can the common law concept of charity law be modernised? There are difficulties with the present jurisprudential conception. The focus of the chapter is not on those difficulties, however, but rather on the development of an alternative architecture for common law jurisprudence. The conclusion to which the chapter comes is that charity law can be modernised by a series of steps to include all civil society organisations. It is possible if the ‘technical’ definition of charitable purpose is abandoned in favour of a contemporary, not technical concept of charitiable purpose. This conclusion is reached by proposing a framework, developed from the common law concept of charities, that reconciles into a cohesive jurisprudential architecture all of the laws applying to civil society organisations, not just charities. In this section, first the argument is contextualised in an idea of society and located in a gap in legal theory. An analogy is then offered to introduce the problems in the legal theory applying, not just to charities, but more broadly to civil society organisations. The substantive challenge of mapping an alternative jurisprudence is then taken in steps. The final substantive section conceptualises the changes inherent in a move beyond charities to a jurisprudence centred on civil society organisations and how this would bring legal theory into line with sectoral analysis in other disciplines.

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This chapter evaluates the rise of creative industries from four standpoints: the growing interest in creativity in the early 21st century; the 'culturalisation' of economic life with the rise of service industries; clustering and uneven development in the cultural economic geography of the creative industries; and the future of arts and cultural policy.

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In an era of hyper-specialization it is unusual to find such a range of concerns as creative economy, media studies, copyright law and 'area' studies, but at the same time it is impossible to do justice to specialist domains without knowing how they fit together.

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The paper addresses the issue of providing access control via delegation and constraint management across multiple security domains. Specifically, this paper proposes a novel Delegation Constraint Management model to manage and enforce delegation constraints across security domains. An algorithm to trace the authority of delegation constraints is introduced as well as an algorithm to form a delegation constraint set and detect/prevent potential conflicts. The algorithms and the management model are built upon a set of formal definitions of delegation constraints. In addition, a constraint profile based on XACML is proposed as a means to express the delegation constraint. The paper also includes a protocol to exchange delegation constraints (in the form of user commitments) between the involved entities in the delegation process.

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Delegation, from the technical point of view, is widely considered as a potential approach in addressing the problem of providing dynamic access control decisions in activities with a high level of collaboration, either within a single security domain or across multiple security domains. Although delegation continues to attract significant attention from the research community, presently, there is no published work that presents a taxonomy of delegation concepts and models. This paper intends to address this gap by presenting a set of taxonomic criteria relevant to the concept of delegation and applies the taxonomy to a selection of significant delegation models published in the literature.

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This paper introduces a model to facilitate delegation, including ad-hoc delegation, in cross security domain activities. Specifically, this paper proposes a novel delegation constraint management model to manage and track delegation constraints across security domains. An algorithm to trace the authority of delegation constraints is introduced as well as an algorithm to form a delegation constraint set and detect/prevent potential conflicts. The algorithms and the management model are built upon a set of formal definitions of delegation constraints.

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Delegation, from a technical point of view, is widely considered as a potential approach in addressing the problem of providing dynamic access control decisions in activities with a high level of collaboration, either within a single security domain or across multiple security domains. Although delegation continues to attract significant attention from the research community, presently, there is no published work that presents a taxonomy of delegation concepts and models. This article intends to address this gap by presenting a set of taxonomic criteria relevant to the concept of delegation. This article also applies the taxonomy to a selection of significant delegation models published in the literature.

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Delegation is a powerful mechanism to provide flexible and dynamic access control decisions. Delegation is particularly useful in federated environments where multiple systems, with their own security autonomy, are connected under one common federation. Although many delegation schemes have been studied, current models do not seriously take into account the issue of delegation commitment of the involved parties. In order to address this issue, this paper introduces a new mechanism to help parties involved in the delegation process to express commitment constraints, perform the commitments and track the committed actions. This mechanism looks at two different aspects: pre-delegation commitment and post-delegation commitment. In pre-delegation commitment, this mechanism enables the involved parties to express the delegation constraints and address those constraints. The post-delegation commitment phase enables those parties to inform the delegator and service providers how the commitments are conducted. This mechanism utilises a modified SAML assertion structure to support the proposed delegation and constraint approach.

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This paper investigates the use of time-frequency techniques to assist in the estimation of power system modes which are resolvable by a Digital Fourier Transform (DFT). The limitations of linear estimation techniques in the presence of large disturbances which excite system non-linearities, particularly the swing equation non-linearity are shown. Where a nonlinearity manifests itself as time varying modal frequencies the Wigner-Ville Distribution (WVD) is used to describe the variation in modal frequencies and construct a window over which standard linear estimation techniques can be used. The error obtained even in the presence of multiple resolvable modes is better than 2%.