424 research outputs found

    LIPIcs, Volume 251, ITCS 2023, Complete Volume

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    LIPIcs, Volume 251, ITCS 2023, Complete Volum

    Concurrent Asynchronous Byzantine Agreement in Expected-Constant Rounds, Revisited

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    It is well known that without randomization, Byzantine agreement (BA) requires a linear number of rounds in the synchronous setting, while it is flat out impossible in the asynchronous setting. The primitive which allows to bypass the above limitation is known as oblivious common coin (OCC). It allows parties to agree with constant probability on a random coin, where agreement is oblivious, i.e., players are not aware whether or not agreement has been achieved. The starting point of our work is the observation that no known protocol exists for information-theoretic multi-valued OCC---i.e., OCC where the coin might take a value from a domain of cardinality larger than 2---with optimal resiliency in the asynchronous (with eventual message delivery) setting. This apparent hole in the literature is particularly problematic, as multi-valued OCC is implicitly or explicitly used in several constructions. (In fact, it is often falsely attributed to the asynchronous BA result by Canetti and Rabin [STOC ’93], which, however, only achieves binary OCC and does not translate to a multi-valued OCC protocol.) In this paper, we present the first information-theoretic multi-valued OCC protocol in the asynchronous setting with optimal resiliency, i.e., tolerating t<n/3t<n/3 corruptions, thereby filling this important gap. Further, our protocol efficiently implements OCC with an exponential-size domain, a property which is not even achieved by known constructions in the simpler, synchronous setting. We then turn to the problem of round-preserving parallel composition of asynchronous BA. A protocol for this task was proposed by Ben-Or and El-Yaniv [Distributed Computing ’03]. Their construction, however, is flawed in several ways: For starters, it relies on multi-valued OCC instantiated by Canetti and Rabin\u27s result (which, as mentioned above, only provides binary OCC). This shortcoming can be repaired by plugging in our above multi-valued OCC construction. However, as we show, even with this fix it remains unclear whether the protocol of Ben-Or and El-Yaniv achieves its goal of expected-constant-round parallel asynchronous BA, as the proof is incorrect. Thus, as a second contribution, we provide a simpler, more modular protocol for the above task. Finally, and as a contribution of independent interest, we provide proofs in Canetti\u27s Universal Composability framework; this makes our work the first one offering composability guarantees, which are important as BA is a core building block of secure multi-party computation protocols

    Just How Fair is an Unreactive World?

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    Fitzi, Garay, Maurer, and Ostrovsky (J. Cryptology 2005) showed that in the presence of a dishonest majority, no primitive of cardinality n−1n - 1 is complete for realizing an arbitrary nn-party functionality with guaranteed output delivery. In this work, we show that in the presence of n−1n - 1 corrupt parties, no unreactive primitive of cardinality n−1n - 1 is complete for realizing an arbitrary nn-party functionality with fairness. We show more generally that for t>n2t > \frac{n}{2}, in the presence of tt malicious parties, no unreactive primitive of cardinality tt is complete for realizing an arbitrary nn-party functionality with fairness. We complement this result by noting that (t+1)(t+1)-wise fair exchange is complete for realizing an arbitrary nn-party functionality with fairness. In order to prove our results, we utilize the primitive of fair coin tossing and the notion of predictability. While this notion has been considered in some form in past works, we come up with a novel and non-trivial framework to employ it, one that readily generalizes from the setting of two parties to multiple parties, and also to the setting of unreactive functionalities

    LIPIcs, Volume 261, ICALP 2023, Complete Volume

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    LIPIcs, Volume 261, ICALP 2023, Complete Volum

    SoK: Public Randomness

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    Public randomness is a fundamental component in many cryptographic protocols and distributed systems and often plays a crucial role in ensuring their security, fairness, and transparency properties. Driven by the surge of interest in blockchain and cryptocurrency platforms and the usefulness of such component in those areas, designing secure protocols to generate public randomness in a distributed manner has received considerable attention in recent years. This paper presents a systematization of knowledge on the topic of public randomness with a focus on cryptographic tools providing public verifiability and key themes underlying these systems. We provide concrete insights on how state-of-the-art protocols achieve this task efficiently in an adversarial setting and present various research gaps that may be suitable for future research

    Scholarly Communication Librarianship and Open Knowledge

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    The intersection of scholarly communication librarianship and open education offers a unique opportunity to expand knowledge of scholarly communication topics in both education and practice. Open resources can address the gap in teaching timely and critical scholarly communication topics—copyright in teaching and research environments, academic publishing, emerging modes of scholarship, impact measurement—while increasing access to resources and equitable participation in education and scholarly communication. Scholarly Communication Librarianship and Open Knowledge is an open textbook and practitioner’s guide that collects theory, practice, and case studies from nearly 80 experts in scholarly communication and open education. Divided into three parts: *What is Scholarly Communication? *Scholarly Communication and Open Culture *Voices from the Field: Perspectives, Intersections, and Case Studies The book delves into the economic, social, policy, and legal aspects of scholarly communication as well as open access, open data, open education, and open science and infrastructure. Practitioners provide insight into the relationship between university presses and academic libraries, defining collection development as operational scholarly communication, and promotion and tenure and the challenge for open access. Scholarly Communication Librarianship and Open Knowledge is a thorough guide meant to increase instruction on scholarly communication and open education issues and practices so library workers can continue to meet the changing needs of students and faculty. It is also a political statement about the future to which we aspire and a challenge to the industrial, commercial, capitalistic tendencies encroaching on higher education. Students, readers, educators, and adaptors of this resource can find and embrace these themes throughout the text and embody them in their work

    Politicians as policy makers in large-scale education system reform: The development of Local Schools, Local Decisions in NSW.

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    Large scale education system reform has been taking place for 60 years and governments are expending increasing effort and money on it. The stakes of their involvement are rising, with education success viewed as a proxy for economic competitiveness. However, whole system improvement – where most schools improve - continues to remain elusive. There is general agreement that ministers are integral to public policy development and that one of the most crucial factors in achieving such reform is managing the political context. However very little systematic research exists on the politics of reform, and the problem for politicians is that there are no firm right answers or solutions that they can apply. The aim of this thesis is to provide insights into the role of politicians as policy makers in the development of large-scale education system reform and to distil lessons and identify a practical strategic framework for reform which might be relevant in other contexts or jurisdictions. It builds on the small literature of the politics of education and the writings of ministers, as well as on the extensive literature on large-scale system reform and public policy development, through a qualitative descriptive case study of the development of the Local Schools, Local Decisions (LSLD) reform in New South Wales, Australia, from 2009 to 2012. It takes an historical narrative approach to identifying the elements of the processes through which this reform was developed by the Minister for Education, the political considerations that arose, and how these were addressed. This is explored from the perspectives of those who were insiders to the process - the Minister and others, such as ministerial office staff, public servants and key stakeholders. Their voices are almost entirely absent in the research on policy development and reform design. This study contributes to knowledge by identifying five key cross-cutting themes which give insights into the role of politicians as policy makers in developing large-scale education system reform. It also distils lessons for ministers and their offices for developing such reforms and creates two practical strategic frameworks which might be relevant in other contexts or jurisdictions

    Cyber-Human Systems, Space Technologies, and Threats

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    CYBER-HUMAN SYSTEMS, SPACE TECHNOLOGIES, AND THREATS is our eighth textbook in a series covering the world of UASs / CUAS/ UUVs / SPACE. Other textbooks in our series are Space Systems Emerging Technologies and Operations; Drone Delivery of CBNRECy – DEW Weapons: Emerging Threats of Mini-Weapons of Mass Destruction and Disruption (WMDD); Disruptive Technologies with applications in Airline, Marine, Defense Industries; Unmanned Vehicle Systems & Operations On Air, Sea, Land; Counter Unmanned Aircraft Systems Technologies and Operations; Unmanned Aircraft Systems in the Cyber Domain: Protecting USA’s Advanced Air Assets, 2nd edition; and Unmanned Aircraft Systems (UAS) in the Cyber Domain Protecting USA’s Advanced Air Assets, 1st edition. Our previous seven titles have received considerable global recognition in the field. (Nichols & Carter, 2022) (Nichols, et al., 2021) (Nichols R. K., et al., 2020) (Nichols R. , et al., 2020) (Nichols R. , et al., 2019) (Nichols R. K., 2018) (Nichols R. K., et al., 2022)https://newprairiepress.org/ebooks/1052/thumbnail.jp

    WiFi-Based Human Activity Recognition Using Attention-Based BiLSTM

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    Recently, significant efforts have been made to explore human activity recognition (HAR) techniques that use information gathered by existing indoor wireless infrastructures through WiFi signals without demanding the monitored subject to carry a dedicated device. The key intuition is that different activities introduce different multi-paths in WiFi signals and generate different patterns in the time series of channel state information (CSI). In this paper, we propose and evaluate a full pipeline for a CSI-based human activity recognition framework for 12 activities in three different spatial environments using two deep learning models: ABiLSTM and CNN-ABiLSTM. Evaluation experiments have demonstrated that the proposed models outperform state-of-the-art models. Also, the experiments show that the proposed models can be applied to other environments with different configurations, albeit with some caveats. The proposed ABiLSTM model achieves an overall accuracy of 94.03%, 91.96%, and 92.59% across the 3 target environments. While the proposed CNN-ABiLSTM model reaches an accuracy of 98.54%, 94.25% and 95.09% across those same environments
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