336 resultados para security protocols


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The article discusses the issues of resistance; that is resistance by prisoners to the various manifestations of power operating in high security prisons, as well as that of attempted shifts in the regime from physical to psychological control. Other topics highlighted include legitimacy and 'official discourse', mourning and the construction of 'ungrievable lives' and the importance of finding a way out of the cycle of violence, which high security regimes perpetuate.

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The growing importance of logistics in increasingly globalised production and consumption systems strengthens the case for explicit consideration of the climate risks that may impact on the operation of ports in the future, as well as the formulation of adaptation responses that act to enhance their resilience. Within a logistics chain, seaports are functional nodes of significant strategic importance, and are considered as critical gateways linking local and national supply chains to global markets. However, they are more likely to be exposed to vagaries of climate-related extreme events due to their coastal locations. As such, they need to be adaptive and respond to the projected impacts of climate change, in particular extreme weather events. These impacts are especially important in the logistics context as they could result in varying degrees of business interruption; including business closure in the worst case scenario. Since trans-shipment of freight for both the import and export of goods and raw materials has a significant impact on Australia’s sustained economic growth it was considered important to undertake a study of port functional assets, to assess their vulnerability to climate change, to model the potential impacts of climate-related extreme events, and to highlight possible adaptation responses.

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For over 150 years Australia has exported bulk, undifferentiated, commodities such as wool, wheat, meat and sugar to the UK and more recently to Japan, Korea, and the Middle East. It is estimated that, each year, Australia's farming system feeds a domestic population of some 22 million people, while exporting enough food to feed another 40 million. With the Australian population expected to double in the next 40 years, and with the anticipated growth in the world's population to reach a level of some 9 billion (from its present level of 7 billion) in the same period, there are strong incentives for an expansion of food production in Australia. Neoliberal settings are encouraging this expansion at the same time as they are facilitating importation of foods, higher levels of foreign direct investment and the commoditisation of resources (such as water). Yet, expansion in food production – and in an era of climate change – will continue to compromise the environment. After discussing Australia's neoliberal framework and its relation to farming, this paper outlines how Australia is attempting to address the issue of food security. It argues that productivist farming approaches that are favoured by both industry and government are proving incapable of bringing about long-term production outcomes that will guarantee national food security.

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Security models for two-party authenticated key exchange (AKE) protocols have developed over time to prove the security of AKE protocols even when the adversary learns certain secret values. In this work, we address more granular leakage: partial leakage of long-term secrets of protocol principals, even after the session key is established. We introduce a generic key exchange security model, which can be instantiated allowing bounded or continuous leakage, even when the adversary learns certain ephemeral secrets or session keys. Our model is the strongest known partial-leakage-based security model for key exchange protocols. We propose a generic construction of a two-pass leakage-resilient key exchange protocol that is secure in the proposed model, by introducing a new concept: the leakage-resilient NAXOS trick. We identify a special property for public-key cryptosystems: pair generation indistinguishability, and show how to obtain the leakage-resilient NAXOS trick from a pair generation indistinguishable leakage-resilient public-key cryptosystem.

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“Supermax” prisons, conceived by the United States in the early 1980s, are typically reserved for convicted political criminals such as terrorists and spies and for other inmates who are considered to pose a serious ongoing threat to the wider community, to the security of correctional institutions, or to the safety of other inmates. Prisoners are usually restricted to their cells for up to twenty-three hours a day and typically have minimal contact with other inmates and correctional staff. Not only does the Federal Bureau of Prisons operate one of these facilities, but almost every state has either a supermax wing or stand-alone supermax prison. The Globalization of Supermax Prisons examines why nine advanced industrialized countries have adopted the supermax prototype, paying particular attention to the economic, social, and political processes that have affected each state. Featuring essays that look at the U.S.-run prisons of Abu Ghraib and Guantanemo, this collection seeks to determine if the American model is the basis for the establishment of these facilities and considers such issues as the support or opposition to the building of a supermax and why opposition efforts failed; the allegation of human rights abuses within these prisons; and the extent to which the decision to build a supermax was influenced by developments in the United States. Additionally, contributors address such domestic matters as the role of crime rates, media sensationalism, and terrorism in each country’s decision to build a supermax prison.

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In Responsibility to Protect and Women, Peace and Security: Aligning the Protection Agendas, editors Davies, Nwokora, Stamnes and Teitt address the intersections of the Responsibility to Protect (R2P) principle and the Women, Peace, and Security (WPS) agenda. Widespread or systematic sexual or gender-based violence is a war crime, a crime against humanity and an act of genocide, all of which are clearly addressed in the R2P principle. The protection of those at risk of widespread sexual violence is therefore not only relative to the Women, Peace and Security (WPS) agenda, but a fundamental sovereign obligation for all states as part of their commitment to R2P. Contributions from policy-makers and academics consider both the merits and the utility of aligning the protection agendas of R2P and WPS. Ultimately, a number of actionable recommendations are made concerning a unification of the agendas to best support the global empowerment of women and prevention of mass atrocities.

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Although there are many approaches for developing secure programs, they are not necessarily helpful for evaluating the security of a pre-existing program. Software metrics promise an easy way of comparing the relative security of two programs or assessing the security impact of modifications to an existing one. Most studies in this area focus on high level source code but this approach fails to take compiler-specific code generation into account. In this work we describe a set of object-oriented Java bytecode security metrics which are capable of assessing the security of a compiled program from the point of view of potential information flow. These metrics can be used to compare the security of programs or assess the effect of program modifications on security using a tool which we have developed to automatically measure the security of a given Java bytecode program in terms of the accessibility of distinguished ‘classified’ attributes.

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Distributed-password public-key cryptography (DPwPKC) allows the members of a group of people, each one holding a small secret password only, to help a leader to perform the private operation, associated to a public-key cryptosystem. Abdalla et al. recently defined this tool [1], with a practical construction. Unfortunately, the latter applied to the ElGamal decryption only, and relied on the DDH assumption, excluding any recent pairing-based cryptosystems. In this paper, we extend their techniques to support, and exploit, pairing-based properties: we take advantage of pairing-friendly groups to obtain efficient (simulation-sound) zero-knowledge proofs, whose security relies on the Decisional Linear assumption. As a consequence, we provide efficient protocols, secure in the standard model, for ElGamal decryption as in [1], but also for Linear decryption, as well as extraction of several identity-based cryptosystems [6,4]. Furthermore, we strenghten their security model by suppressing the useless testPwd queries in the functionality.

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We introduce the notion of distributed password-based public-key cryptography, where a virtual high-entropy private key is implicitly defined as a concatenation of low-entropy passwords held in separate locations. The users can jointly perform private-key operations by exchanging messages over an arbitrary channel, based on their respective passwords, without ever sharing their passwords or reconstituting the key. Focusing on the case of ElGamal encryption as an example, we start by formally defining ideal functionalities for distributed public-key generation and virtual private-key computation in the UC model. We then construct efficient protocols that securely realize them in either the RO model (for efficiency) or the CRS model (for elegance). We conclude by showing that our distributed protocols generalize to a broad class of “discrete-log”-based public-key cryptosystems, which notably includes identity-based encryption. This opens the door to a powerful extension of IBE with a virtual PKG made of a group of people, each one memorizing a small portion of the master key.

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We revisit the venerable question of access credentials management, which concerns the techniques that we, humans with limited memory, must employ to safeguard our various access keys and tokens in a connected world. Although many existing solutions can be employed to protect a long secret using a short password, those solutions typically require certain assumptions on the distribution of the secret and/or the password, and are helpful against only a subset of the possible attackers. After briefly reviewing a variety of approaches, we propose a user-centric comprehensive model to capture the possible threats posed by online and offline attackers, from the outside and the inside, against the security of both the plaintext and the password. We then propose a few very simple protocols, adapted from the Ford-Kaliski server-assisted password generator and the Boldyreva unique blind signature in particular, that provide the best protection against all kinds of threats, for all distributions of secrets. We also quantify the concrete security of our approach in terms of online and offline password guesses made by outsiders and insiders, in the random-oracle model. The main contribution of this paper lies not in the technical novelty of the proposed solution, but in the identification of the problem and its model. Our results have an immediate and practical application for the real world: they show how to implement single-sign-on stateless roaming authentication for the internet, in a ad-hoc user-driven fashion that requires no change to protocols or infrastructure.

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Since their introduction, the notions of indistinguishability and non-malleability have been changed and extended by different authors to support different goals. In this paper, we propose new flavors of these notions, investigate their relative strengths with respect to previous notions, and provide the full picture of relationships (i.e., implications and separations) among the security notions for public-key encryption schemes. We take into account the two general security goals of indistinguishability and non-malleability, each in the message space, key space, and hybrid message-key space to find six specific goals, a couple of them, namely complete indistinguishability and key non-malleability, are new. Then for each pair of goals, coming from the indistinguishability or non-malleability classes, we prove either an implication or a separation, completing the full picture of relationships among all these security notions. The implications and separations are respectively supported by formal proofs (i.e., reductions) in the concrete-security framework and by counterexamples.

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Recently, a convex hull-based human identification protocol was proposed by Sobrado and Birget, whose steps can be performed by humans without additional aid. The main part of the protocol involves the user mentally forming a convex hull of secret icons in a set of graphical icons and then clicking randomly within this convex hull. While some rudimentary security issues of this protocol have been discussed, a comprehensive security analysis has been lacking. In this paper, we analyze the security of this convex hull-based protocol. In particular, we show two probabilistic attacks that reveal the user’s secret after the observation of only a handful of authentication sessions. These attacks can be efficiently implemented as their time and space complexities are considerably less than brute force attack. We show that while the first attack can be mitigated through appropriately chosen values of system parameters, the second attack succeeds with a non-negligible probability even with large system parameter values that cross the threshold of usability.

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Classical results in unconditionally secure multi-party computation (MPC) protocols with a passive adversary indicate that every n-variate function can be computed by n participants, such that no set of size t < n/2 participants learns any additional information other than what they could derive from their private inputs and the output of the protocol. We study unconditionally secure MPC protocols in the presence of a passive adversary in the trusted setup (‘semi-ideal’) model, in which the participants are supplied with some auxiliary information (which is random and independent from the participant inputs) ahead of the protocol execution (such information can be purchased as a “commodity” well before a run of the protocol). We present a new MPC protocol in the trusted setup model, which allows the adversary to corrupt an arbitrary number t < n of participants. Our protocol makes use of a novel subprotocol for converting an additive secret sharing over a field to a multiplicative secret sharing, and can be used to securely evaluate any n-variate polynomial G over a field F, with inputs restricted to non-zero elements of F. The communication complexity of our protocol is O(ℓ · n 2) field elements, where ℓ is the number of non-linear monomials in G. Previous protocols in the trusted setup model require communication proportional to the number of multiplications in an arithmetic circuit for G; thus, our protocol may offer savings over previous protocols for functions with a small number of monomials but a large number of multiplications.

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The sum of k mins protocol was proposed by Hopper and Blum as a protocol for secure human identification. The goal of the protocol is to let an unaided human securely authenticate to a remote server. The main ingredient of the protocol is the sum of k mins problem. The difficulty of solving this problem determines the security of the protocol. In this paper, we show that the sum of k mins problem is NP-Complete and W[1]-Hard. This latter notion relates to fixed parameter intractability. We also discuss the use of the sum of k mins protocol in resource-constrained devices.

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We present two unconditional secure protocols for private set disjointness tests. In order to provide intuition of our protocols, we give a naive example that applies Sylvester matrices. Unfortunately, this simple construction is insecure as it reveals information about the intersection cardinality. More specifically, it discloses its lower bound. By using the Lagrange interpolation, we provide a protocol for the honest-but-curious case without revealing any additional information. Finally, we describe a protocol that is secure against malicious adversaries. In this protocol, a verification test is applied to detect misbehaving participants. Both protocols require O(1) rounds of communication. Our protocols are more efficient than the previous protocols in terms of communication and computation overhead. Unlike previous protocols whose security relies on computational assumptions, our protocols provide information theoretic security. To our knowledge, our protocols are the first ones that have been designed without a generic secure function evaluation. More important, they are the most efficient protocols for private disjointness tests in the malicious adversary case.