384 research outputs found

    Using rhythmic nonces for puzzle-based DoS resistance

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    To protect against replay attacks, many Internet proto-cols rely on nonces to guarantee freshness. In practice, the server generates these nonces during the initial hand-shake, but if the server is under attack, resources con-sumed by managing certain protocols can lead to DoS vulnerabilities. To help alleviate this problem, we pro-pose the concept of rhythmic nonces, a cryptographic tool that allows servers to measure request freshness with minimal bookkeeping costs. We explore the impact of this service in the context of a puzzle-based DoS re-sistance scheme we call “SYN puzzles”. Our preliminary results based on mathematical analysis and evaluation of a prototype suggests that our scheme is more resistant than existing techniques. 1

    Cognitive Machine Individualism in a Symbiotic Cybersecurity Policy Framework for the Preservation of Internet of Things Integrity: A Quantitative Study

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    This quantitative study examined the complex nature of modern cyber threats to propose the establishment of cyber as an interdisciplinary field of public policy initiated through the creation of a symbiotic cybersecurity policy framework. For the public good (and maintaining ideological balance), there must be recognition that public policies are at a transition point where the digital public square is a tangible reality that is more than a collection of technological widgets. The academic contribution of this research project is the fusion of humanistic principles with Internet of Things (IoT) technologies that alters our perception of the machine from an instrument of human engineering into a thinking peer to elevate cyber from technical esoterism into an interdisciplinary field of public policy. The contribution to the US national cybersecurity policy body of knowledge is a unified policy framework (manifested in the symbiotic cybersecurity policy triad) that could transform cybersecurity policies from network-based to entity-based. A correlation archival data design was used with the frequency of malicious software attacks as the dependent variable and diversity of intrusion techniques as the independent variable for RQ1. For RQ2, the frequency of detection events was the dependent variable and diversity of intrusion techniques was the independent variable. Self-determination Theory is the theoretical framework as the cognitive machine can recognize, self-endorse, and maintain its own identity based on a sense of self-motivation that is progressively shaped by the machine’s ability to learn. The transformation of cyber policies from technical esoterism into an interdisciplinary field of public policy starts with the recognition that the cognitive machine is an independent consumer of, advisor into, and influenced by public policy theories, philosophical constructs, and societal initiatives

    Privacy-preserving energy management techniques and delay-sensitive transmission strategies for smart grids

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    The smart grid (SG) is the enhancement of the traditional electricity grid that allows bidirectional flow of electricity and information through the integration of advanced monitoring, communication and control technologies. In this thesis, we focus on important design problems affecting particularly two critical enabling components of the SG infrastructure : smart meters (SMs) and wireless sensor networks (WSNs). SMs measure the energy consumption of the users and transmit their readings to the utility provider in almost real-time. SM readings enable real-time optimization of load management. However, possible misuse of SM readings raises serious privacy concerns for the users. The challenge is thus to design techniques that can increase the privacy of the users while maintaining the monitoring capabilities SMs provide. Demand-side energy management (EM), achieved thanks to the utilization of storage units and alternative energy sources, has emerged as a potential technique to tackle this challenge. WSNs consist of a large number of low power sensors, which monitor physical parameters and transmit their measurements to control centers (CCs) over wireless links. CCs utilize these measurements to reconstruct the system state. For the reliable management of the SG, near real-time and accurate reconstruction of the system state at the CC is crucial. Thus, low complexity delay-constrained transmission strategies, which enable sensors to accurately transmit their measurements to CCs, should be investigated rigorously. To address these challenges, this dissertation investigates and designs privacy-preserving EM techniques for SMs and delay-constrained transmission strategies for WSNs. The proposed EM techniques provide privacy to SM users while maintaining the operational benefits SMs provide. On the other hand, the proposed transmission strategies enable WSNs to meet low latency transmission requirements, which in turn, facilitate real-time and accurate state reconstruction; and hence, the efficient and robust management of the SG. First, we consider an SM system with energy harvesting and storage units. Representing the system with a discrete-time finite state model, we study stochastic EM policies from a privacy-energy efficiency trade-off perspective, where privacy is measured by information leakage rate and energy efficiency is measured by wasted energy rate. We propose EM policies that take stochastic output load decisions based on the harvested energy, the input load and the state of the battery. For the proposed policies, we characterize the fundamental trade-off between user's privacy and energy efficiency. Second, we consider an SM system with a storage unit. Considering a discrete-time power consumption and pricing model, we study EM policies from a privacy-cost trade-off perspective, where privacy is measured by the load variance as well as mutual information. Assuming non-causal knowledge of the power demand profile and prices, we characterize the optimal EM policy based on the solution of an optimization problem. Then, assuming that the power demand profile is known only causally, we obtain the optimal EM policy based on dynamic programming, and also propose a low complexity heuristic policy. For the proposed policies, we characterize the trade-off between user's privacy and energy cost. Finally, we study the delay-constrained linear transmission (LT) of composite Gaussian measurements from a sensor to a CC over a point-to-point fading channel. Assuming that the channel state information (CSI) is known by both the encoder and decoder, we propose the optimal LT strategy in terms of the average mean-square error (MSE) distortion under a strict delay constraint, and two LT strategies under general delay constraints. Assuming that the CSI is known only by the decoder, we propose the optimal LT strategy in terms of the average MSE distortion under a strict delay constraint.La red de energía inteligente (SG) es la mejora de la red eléctrica tradicional. En esta tesis, nos enfocamos en las problemáticas asociadas al diseño de dos de los componentes más críticos de la infraestructura de la SG : los medidores inteligentes (SMs) y las redes de sensores inalámbricos (WSNs). Los SMs miden el consumo de energía de los usuarios y transmiten sus medidas al proveedor de servicio casi en tiempo real. Las medidas de SM permiten la optimización en tiempo real de la gestión de carga en la red. Sin embargo, el posible mal uso de estas medidas plantea preocupaciones graves en cuanto a la privacidad de los usuarios. El desafío es, por lo tanto, diseñar técnicas que puedan aumentar la privacidad de los usuarios manteniendo las capacidades de supervisión que proveen los SMs. Una solución tecnológica es el diseño de sistemas de gestión de energía (EM) inteligentes compuestos por dispositivos de almacenamiento y generación alternativa de energía. Las WSNs se componen de un gran número de sensores, que miden parámetros físicos y transmiten sus mediciones a los centros de control (CCs) mediante enlaces inalámbricos. Los CCs utilizan estas mediciones para estimar el estado del sistema. Para una gestión fiable de la SG, una buena reconstrucción del estado del sistema en tiempo real es crucial. Por ello, es preciso investigar estrategias de transmisión con estrictos requisitos de complejidad y limitaciones de latencia. Para afrontar estos desafíos, esta tesis investiga y diseña técnicas de EM para preservar la privacidad de los usuarios de SM y estrategias de transmisión para WSNs con limitaciones de latencia. Las técnicas de EM propuestas proporcionan privacidad a los consumidores de energía manteniendo los beneficios operacionales para la SG. Las estrategias de transmisión propuestas permiten a las WSNs satisfacer los requisitos de baja latencia necesarios para la reconstrucción precisa del estado en tiempo real; y por lo tanto, la gestión eficiente y robusta de la SG. En primer lugar, consideramos el diseño de un sistema de SM con una unidad de almacenamiento y generación de energía renovable. Representando el sistema con un modelo de estados finitos y de tiempo discreto, proponemos políticas estocásticas de EM. Para las políticas propuestas, caracterizamos la relación fundamental existente entre la privacidad y la eficiencia de energía del usuario, donde la privacidad se mide mediante la tasa de fuga de información y la eficiencia de energía se mide mediante la tasa de energía perdida. En segundo lugar, consideramos el diseño de un sistema de SM con una unidad de almacenamiento. Considerando un modelo de tiempo discreto, estudiamos la relación existente entre la privacidad y el coste de la energía, donde la privacidad se mide por la variación de la carga, así como la información mutua. Suponiendo que el perfil de la demanda de energía y los precios son conocidos de antemano, caracterizamos la política de EM óptima. Suponiendo que la demanda de energía es conocida sólo para el tiempo actual, obtenemos la política de EM óptima mediante programación dinámica, y proponemos una política heurística de baja complejidad. Para las políticas propuestas, caracterizamos la relación existente entre la privacidad y el coste de energía del usuario. Finalmente, consideramos el diseño de estrategias de transmisión lineal (LT) de mediciones Gaussianas compuestas desde un sensor a un CC sobre un canal punto a punto con desvanecimientos. Suponiendo que la información del estado del canal (CSI) es conocida tanto por el trasmisor como por el receptor, proponemos la estrategia de LT óptima en términos de la distorsión de error cuadrático medio (MSE) bajo una restricción de latencia estricta y dos estrategias de LT para restricciones de latencia arbitrarias. Suponiendo que la CSI es conocida sólo en el receptor, proponemos la estrategia de LT óptima en términos de la distorsión de MSE bajo una restricción de latencia estricta.La xarxa d'energia intel·ligent (SG) és la millora de la xarxa elèctrica tradicional. En aquesta tesi, ens enfoquem en les problemàtiques associades al disseny de dos dels components més crítics de la infraestructura de la SG : els mesuradors de consum intel·ligents(SMs) i les xarxes de sensors sense fils (WSNs).Els SMs mesuren el consum d'energia dels usuaris i transmeten les seves mesures al proveïdor de servei gairebé en temps real. Les mesures de SM permeten l'optimització en temps real de la gestió de càrrega a la xarxa. No obstant això, el possible mal ús d'aquestes mesures planteja preocupacions greus en quant a la privacitat dels usuaris. El desafiament és, per tant, dissenyar tècniques que puguin augmentar la privadesa dels usuaris mantenint les capacitats de supervisió que proveeixen els SMs. Una solució tecnològica és el disseny de sistemes de gestió d'energia (EM) intel·ligents compostos per dispositius d'emmagatzematge i generació alternativa d'energia.Les WSNs es componen d'un gran nombre de sensors, que mesuren paràmetres físics i transmeten les seves mesures als centres de control (CCs) mitjançant enllaços sense fils. Els CCs utilitzen aquestes mesures per estimar l'estat del sistema. Per a una gestió fiable de la SG, una bona reconstrucció de l'estat del sistema en temps real és crucial. Per això, cal investigar estratègies de transmissió amb estrictes requisits de complexitat i limitacions de latència. Per d'afrontar aquests desafiaments, aquesta tesi investiga i dissenya tècniques d'EM per preservar la privacitat dels usuaris de SM i estratègies de transmissió per WSNs amb limitacions de latència. Les tècniques d'EM propostes proporcionen privacitats als consumidors d'energia mantenint els beneficis operacionals per la SG. Les estratègies de transmissió proposades permeten a les WSNs satisfer els requisits de baixa latència necessaris per a la reconstrucció precisa de l'estat en temps real; i per tant, la gestió eficient i robusta de la SG.En primer lloc, considerem el disseny d'un sistema de SM amb una unitat d'emmagatzematge i generació d'energia renovable. Representant el sistema amb un model d'estats finits i de temps discret, proposem polítiques estocàstiques d'EM. Per a les polítiques propostes, caracteritzem la relació fonamental existent entre la privadesa i l'eficiència d'energia de l'usuari, on la privacitat es mesura mitjançant la taxa de fugida d'informació i l'eficiència d'energia es mesura mitjançant la taxa d'energia perduda.En segon lloc, considerem el disseny d'un sistema de SM amb una unitat d'emmagatzematge. Considerant un model de temps discret, estudiem la relació existent entre la privacitat el cost de l'energia, on la privacitat es mesura per la variació de la càrrega, així com mitjançant la informació mútua. Suposant que la corba de la demanda d'energia i els preus són coneguts per endavant, caracteritzem la política d'EM òptima. Suposant que la demanda d'energia és coneguda només per al temps actual, obtenim la política d'EM òptima mitjançant programació dinàmica, i proposem una política heurística de baixa complexitat. Per a les polítiques propostes, caracteritzem la relació existent entre la privacitat i el cost d'energia de l'usuari.Finalment, considerem el disseny d'estratègies de transmissió lineal (LT) de mesures Gaussianes compostes des d'un sensor a un CC sobre un canal punt a punt amb esvaïments. Suposant que la informació de l'estat del canal (CSI) és coneguda tant pel transmissor com pel receptor, proposem l'estratègia de LT òptima en termes de la distorsió d'error quadràtic mitjà (MSE) sota una restricció de latència estricta. A més, proposem dues estratègies de LT per a restriccions de latència arbitràries. Finalment, suposant que la CSI és coneguda només en el receptor, proposem l'estratègia de LT òptima en termes de la distorsió de MSE sota una restricció de latència estricta

    Big Data Analytics, Insurtech and Consumer Contracts: A European Appraisal

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    The article investigates, from the European perspective, to what extent the enhanced availability of granular data to insurance companies and the growing sophistication of insurers’ processing capabilities through big data analytics (BDA) are fostering the increasing personalization of insurance products and services for consumers. To this purpose, the article first explores the very notion of ‘automated personalization’ in insurance, and then delves into the institutional, epistemic, economic and legal factors that, in Europe, work as a constraint, at least in the short-term, to paradigmatic shifts in insurance consumers contracts. The analysis will hopefully demonstrate that automated personalization in consumer insurance contracts, in Europe, is for the time being more a myth than a reality. What does exist, by contrast, is a no less problematic trend towards mass customization and robotization of consumer insurance contracts, which fully deserves lawyers’ attention

    Application-specific Design and Optimization for Ultra-Low-Power Embedded Systems

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    University of Minnesota Ph.D. dissertation. August 2019. Major: Electrical/Computer Engineering. Advisor: John Sartori. 1 computer file (PDF); xii, 101 pages.The last few decades have seen a tremendous amount of innovation in computer system design to the point where electronic devices have become very inexpensive. This has brought us on the verge of a new paradigm in computing where there will be hundreds of devices in a person’s environment, ranging from mobile phones to smart home devices to wearables to implantables, all interconnected. This paradigm, called the Internet of Things (IoT), brings new challenges in terms of power, cost, and security. For example, power and energy have become critical design constraints that not only affect the lifetime of an ultra-low-power (ULP) system, but also its size and weight. While many conventional techniques exist that are aimed at energy reduction or that improve energy efficiency, they do so at the cost of performance. As such, their impact is limited in circumstances where energy is very constrained or where significant degradation of performance or functionality is unacceptable. Focusing on the opposing demands to increase both energy efficiency and performance simultaneously in a world where Moore’s law scaling is decelerating, one of the underlying themes of this work has been to identify novel insights that enable new pathways to energy efficiency in computing systems while avoiding the conventional tradeoff that simply sacrifices performance and functionality for energy efficiency. To this end, this work proposes a method to analyze the behavior of an application on the gate-level netlist of a processor for all possible inputs using a novel symbolic hardware-software co-analysis methdology. Using this methodology several techniques have been proposed to optimize a given processor-application pair for power, area and security

    Democracy Enhancing Technologies: Toward deployable and incoercible E2E elections

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    End-to-end verifiable election systems (E2E systems) provide a provably correct tally while maintaining the secrecy of each voter's ballot, even if the voter is complicit in demonstrating how they voted. Providing voter incoercibility is one of the main challenges of designing E2E systems, particularly in the case of internet voting. A second challenge is building deployable, human-voteable E2E systems that conform to election laws and conventions. This dissertation examines deployability, coercion-resistance, and their intersection in election systems. In the course of this study, we introduce three new election systems, (Scantegrity, Eperio, and Selections), report on two real-world elections using E2E systems (Punchscan and Scantegrity), and study incoercibility issues in one deployed system (Punchscan). In addition, we propose and study new practical primitives for random beacons, secret printing, and panic passwords. These are tools that can be used in an election to, respectively, generate publicly verifiable random numbers, distribute the printing of secrets between non-colluding printers, and to covertly signal duress during authentication. While developed to solve specific problems in deployable and incoercible E2E systems, these techniques may be of independent interest

    Short-lived zero-knowledge proofs and signatures

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    We introduce the short-lived proof, a non-interactive proof of knowledge with a novel feature: after a specified period of time, the proof is no longer convincing. This time-delayed loss of soundness happens naturally without further involvement from the prover or any third party. We propose formal definitions for short-lived proofs as well as the special case of short-lived signatures. We show several practical constructions built using verifiable delay functions (VDFs). The key idea in our approach is to allow any party to forge any proof by executing a large sequential computation. Some constructions achieve a stronger property called reusable forgeability in which one sequential computation allows forging an arbitrary number of proofs of different statements. Our work also introduces two novel types of VDFs, re-randomizable VDFs and zero-knowledge VDFs, which may be of independent interest

    Secure Remote Storage of Logs with Search Capabilities

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    Dissertação de Mestrado em Engenharia InformáticaAlong side with the use of cloud-based services, infrastructure and storage, the use of application logs in business critical applications is a standard practice nowadays. Such application logs must be stored in an accessible manner in order to used whenever needed. The debugging of these applications is a common situation where such access is required. Frequently, part of the information contained in logs records is sensitive. This work proposes a new approach of storing critical logs in a cloud-based storage recurring to searchable encryption, inverted indexing and hash chaining techniques to achieve, in a unified way, the needed privacy, integrity and authenticity while maintaining server side searching capabilities by the logs owner. The designed search algorithm enables conjunctive keywords queries plus a fine-grained search supported by field searching and nested queries, which are essential in the referred use case. To the best of our knowledge, the proposed solution is also the first to introduce a query language that enables complex conjunctive keywords and a fine-grained search backed by field searching and sub queries.A gerac¸ ˜ao de logs em aplicac¸ ˜oes e a sua posterior consulta s˜ao fulcrais para o funcionamento de qualquer neg´ocio ou empresa. Estes logs podem ser usados para eventuais ac¸ ˜oes de auditoria, uma vez que estabelecem uma baseline das operac¸ ˜oes realizadas. Servem igualmente o prop´ osito de identificar erros, facilitar ac¸ ˜oes de debugging e diagnosticar bottlennecks de performance. Tipicamente, a maioria da informac¸ ˜ao contida nesses logs ´e considerada sens´ıvel. Quando estes logs s˜ao armazenados in-house, as considerac¸ ˜oes relacionadas com anonimizac¸ ˜ao, confidencialidade e integridade s˜ao geralmente descartadas. Contudo, com o advento das plataformas cloud e a transic¸ ˜ao quer das aplicac¸ ˜oes quer dos seus logs para estes ecossistemas, processos de logging remotos, seguros e confidenciais surgem como um novo desafio. Adicionalmente, regulac¸ ˜ao como a RGPD, imp˜oe que as instituic¸ ˜oes e empresas garantam o armazenamento seguro dos dados. A forma mais comum de garantir a confidencialidade consiste na utilizac¸ ˜ao de t ´ecnicas criptogr ´aficas para cifrar a totalidade dos dados anteriormente `a sua transfer ˆencia para o servidor remoto. Caso sejam necess´ arias capacidades de pesquisa, a abordagem mais simples ´e a transfer ˆencia de todos os dados cifrados para o lado do cliente, que proceder´a `a sua decifra e pesquisa sobre os dados decifrados. Embora esta abordagem garanta a confidencialidade e privacidade dos dados, rapidamente se torna impratic ´avel com o crescimento normal dos registos de log. Adicionalmente, esta abordagem n˜ao faz uso do potencial total que a cloud tem para oferecer. Com base nesta tem´ atica, esta tese prop˜oe o desenvolvimento de uma soluc¸ ˜ao de armazenamento de logs operacionais de forma confidencial, integra e autˆ entica, fazendo uso das capacidades de armazenamento e computac¸ ˜ao das plataformas cloud. Adicionalmente, a possibilidade de pesquisa sobre os dados ´e mantida. Essa pesquisa ´e realizada server-side diretamente sobre os dados cifrados e sem acesso em momento algum a dados n˜ao cifrados por parte do servidor..
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