36 research outputs found

    Facilitating Internet of Things on the Edge

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    The evolution of electronics and wireless technologies has entered a new era, the Internet of Things (IoT). Presently, IoT technologies influence the global market, bringing benefits in many areas, including healthcare, manufacturing, transportation, and entertainment. Modern IoT devices serve as a thin client with data processing performed in a remote computing node, such as a cloud server or a mobile edge compute unit. These computing units own significant resources that allow prompt data processing. The user experience for such an approach relies drastically on the availability and quality of the internet connection. In this case, if the internet connection is unavailable, the resulting operations of IoT applications can be completely disrupted. It is worth noting that emerging IoT applications are even more throughput demanding and latency-sensitive which makes communication networks a practical bottleneck for the service provisioning. This thesis aims to eliminate the limitations of wireless access, via the improvement of connectivity and throughput between the devices on the edge, as well as their network identification, which is fundamentally important for IoT service management. The introduction begins with a discussion on the emerging IoT applications and their demands. Subsequent chapters introduce scenarios of interest, describe the proposed solutions and provide selected performance evaluation results. Specifically, we start with research on the use of degraded memory chips for network identification of IoT devices as an alternative to conventional methods, such as IMEI; these methods are not vulnerable to tampering and cloning. Further, we introduce our contributions for improving connectivity and throughput among IoT devices on the edge in a case where the mobile network infrastructure is limited or totally unavailable. Finally, we conclude the introduction with a summary of the results achieved

    Digital transformation in the footwear industry : assessing the potential of IoT on portuguese SMEs in the footwear industry

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    In the last few years, manufacturing companies, from the most diverse industries and sectors, have been investing in industry 4.0 technologies. One of these technologies is the Internet of Things (IoT), which has been revolutionising industries, namely manufacturing, healthcare, energy, retail, and agriculture. Manufacturing firms are adopting IoT not only to improve quality, production and reduce costs but also to enhance the logistic chain and improve customer experience. However, very little progress has been made in the Portuguese footwear industry towards the implementation of the Internet of Things, particularly in the SME segment. This dissertation has analysed the potential operational and production advantages of IoT, the associated economic impact, as well as the limitations of this technology and the challenges for its implementation in Portuguese footwear SMEs. Finally, this dissertation aims to present an adoption roadmap. The results provided positive indicators of operational and productivity gains translated into cost reduction in work insurance, energy, travelling, acquisition of raw materials and decrease of inventory units, and production waste. Nevertheless, the associated potential of each IoT use case is dependent on the capacity of Portuguese footwear SMEs to invest and acquire the necessary technical resources. The main barriers to the adoption of IoT derive from the limitations of the technology and the specific challenges associated to the Portuguese footwear SMEs economic and technical framework. Nonetheless, the technological advances, the cross collaboration among the different footwear stakeholders, and a well-defined implementation strategy can overcome these barriers and bring operational and economic benefits.A Internet of Things (IoT), uma tecnologia da indústria 4.0, tem revolucionado indústrias como a da manufactura, saúde, energia, retalho e agricultura. As empresas de manufactura estão a adoptar a IoT não apenas para melhorar a qualidade dos productos, eficiência produtiva, e reduzir custos, mas também para aprimorar a cadeia logística e melhorar a experiência do cliente. Contudo, poucos foram os progressos feitos referentes à IoT na indústria do calçado Português, principalmente no segmento das PMEs. A seguinte dissertação analisou as potenciais vantagens operacionais e productivas da IoT e os seus impactos económicos, bem como as limitações da tecnologia e os desafios de implementação para as PME do calçado Português. Por último, é apresentado um plano de implementação da tecnologia. Subsequentemente os resultados mostraram indicadores favoráveis de ganhos operacionais e produtivos, que se traduzem na redução de custos com seguros de trabalho, inventário, desperdícios de produção, custos de manutenção, encargos com deslocações, custos de energia e custos de aquisição de matérias-primas. Contudo, o potencial de cada caso de uso de IoT depende da capacidade das PMEs do calçado Português para fazer o investimento financeiro e adquirir os recursos técnicos necessários. As principais barreiras à adopção da IoT derivam das limitações da própria tecnologia e dos desafios relativos ao quadro económico e técnico das PMEs Portuguesas do calçado. Não obstante, os avanços tecnológicos, a colaboração entre os diferentes intervenientes e uma estratégia de implementação bem definida podem superar estas barreiras e garantir a adopção e trazer ganhos operacionais e económicos

    Mission-Critical Communications from LMR to 5G: a Technology Assessment approach for Smart City scenarios

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    Radiocommunication networks are one of the main support tools of agencies that carry out actions in Public Protection & Disaster Relief (PPDR), and it is necessary to update these communications technologies from narrowband to broadband and integrated to information technologies to have an effective action before society. Understanding that this problem includes, besides the technical aspects, issues related to the social context to which these systems are inserted, this study aims to construct scenarios, using several sources of information, that helps the managers of the PPDR agencies in the technological decisionmaking process of the Digital Transformation of Mission-Critical Communication considering Smart City scenarios, guided by the methods and approaches of Technological Assessment (TA).As redes de radiocomunicações são uma das principais ferramentas de apoio dos órgãos que realizam ações de Proteção Pública e Socorro em desastres, sendo necessário atualizar essas tecnologias de comunicação de banda estreita para banda larga, e integra- las às tecnologias de informação, para se ter uma atuação efetiva perante a sociedade . Entendendo que esse problema inclui, além dos aspectos técnicos, questões relacionadas ao contexto social ao qual esses sistemas estão inseridos, este estudo tem por objetivo a construção de cenários, utilizando diversas fontes de informação que auxiliem os gestores destas agências na tomada de decisão tecnológica que envolve a transformação digital da Comunicação de Missão Crítica considerando cenários de Cidades Inteligentes, guiado pelos métodos e abordagens de Avaliação Tecnológica (TA)

    Inteligência Ambiente em serviços de saúde baseada em ontologias e na descoberta de conhecimento em bases de dados e/ou bases de conhecimento

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    Tese de doutoramento em Engenharia BiomédicaAvanços em novas Metodologias para a Resolução de Problemas e o uso de Tecnologias de Informação e Comunicação (TIC) possibilitam uma nova conceção dos processos ao nível dos Serviços de Saúde, baseados no uso e na integração de dados e conhecimentos a todos os níveis, num ambiente relacionado com Instituições de Saúde. De facto, as novas tecnologias de comunicação suportarão a transição de uma aproximação baseada na instituição, para uma abordagem baseada no utente, i.e., o Sistema de Saúde está confrontado com uma série de desafios, nomeadamente os relacionados com a qualidade da informação e o custo de tais processos. Por outro lado, o nível de saúde já atingido em Portugal não permite uma degradação do nível e qualidade de serviços já oferecidos aos cidadãos a quem constitucionalmente é garantido o direto à saúde. Importa encontrar formas de concertar a governação clínica (clinical governance) com a gestão económica dos serviços de saúde, muito particularmente para a desejada sustentabilidade do Serviço Nacional de Saúde. A prestação de cuidados de saúde a custos controlados, dotando o utente de capacidade para participar nesse processo, e a utilização e reutilização de informação, são aspetos importantes para a instituição prestadora de cuidados de saúde. O nosso principal intuito será o de encontrar formas e métodos de superação da atual dispersão de informação nos diversos serviços, departamentos e setores da saúde, muito coincidentes com a situação deficitária, por vezes desagregada, dissociada dos problemas, onde impera a desmotivação e se propiciam assimetrias nos cuidados de saúde sejam hospitalares, ou ao nível dos cuidados primários e outros. Importará garantir a acessibilidade aos cidadãos, particularmente aos doentes, disponibilizando cuidados de saúde oportunos, integradores, que respeitem as reais necessidades de saúde das pessoas e sejam administrados segundo as melhores práticas de gestão clínica e de administração. Para promover tal desiderato importa articular e integrar procedimentos, controlar metas e resultados. Importará maximizar a utilização das TIC’s, exigindo-se para tal soluções de integração e interoperabilidade de processos, criando verdadeiros sistemas de informação integrados, multidisciplinares, que considerem as necessidades e legítimos interesses dos stakeholders da saúde. As infraestruturas das TIC’s deverão, por conseguinte, refletir a visão do sistema de prestação de cuidados de saúde de forma não intrusiva, onde a informação possa fluir de forma transparente entre as instituições e os profissionais de saúde. Assim, o trabalho desenvolvido e apresentado nesta tese abordará aspetos chave que deverão estar relacionados com a utilização da tecnologia e dos sistemas de informação numa visão centrada no utente, na prestação de cuidados de saúde e na gestão e prevenção de doenças. Tratar-se-á de consolidar uma visão global da assistência hospitalar, articulada e integrada com outros setores e saberes, oferecendo aos cidadãos cuidados de saúde garantidamente adequados, sustentados em processos de integração da informação e de automação aceitáveis e oportunos, atendendo às ontologias médicas e melhores práticas profissionais, que transmitam maior proximidade aos utentes, permitindo, no limite, monitorizar e tratar os doentes no seu domicílio.Advances in new Methodologies for Problem Solving and Information Technology enable a fundamental redesign of health care processes based on the use and integration of data and/or knowledge at all levels, in a healthcare environment. Indeed, new communication technologies will support the transition from institution centric to patient-centric based applications, i.e., the health care system is faced with a series of challenges, namely those concerning quality-ofinformation and the cost-effectiveness of such processes. On the other hand, the health level achieved in Portugal does not allow anymore the degradation of the quality of services provided to citizens, to whom, constitutionally, is guaranteed the right to have health care treatments. It is important to gather clinical governance with the economic management of health care services, particularly to achieve the desired sustainability of the National Health Service (Serviço Nacional de Saúde). The distribution of cost-effective health care allowing the patient to take active part in the caring process, provision of evidence based care on all levels in the system and effective use and reuse of information are key issues for the health care organization. Our main aim will be the finding of ways and methods to overpass the actual scattering of information through the services, departments and health sectors, where personal motivation is difficult to attain, and the health care treatments are becoming disparate, at all levels. It should be guaranteed, to the citizens, mainly the sick or the needy, providing timely health care concerning the real needs of people through practices recognized as the best, from the clinical point of view. To promote such goal it is important to integrate procedures and to control results. The use of IT’s should be maximized through the application of interoperability procedures, creating truly integrated information services, considering the needs and interests of the health care stakeholders. The information and communication technology infrastructure should, therefore, reflect the view of the health care system as a seamless system where information can flow across organizational and professional borders. Thus, the work presented in this thesis, it will be address key principles that must be at the center of patient-centered use of technologies for the health care and disease management and prevention. A global vision of hospital assistance will be gathered, integrated with other sectors an know-how, providing citizens with adequate health care services, supported by information integration and automation procedures acceptable and secure, respecting clinical ontologies and the best medical practices, insuring the needed proximity to citizens, allowing, at the limit, to monitor ant to give care to patients at home

    Collaborative networks in ambient assisted living

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    Tese de doutoramento em InformáticaCollaborative Work plays an important role in today’s organizations, especially in areas where decisions must be made. However, any decision that involves a collective or group of decision makers is, by itself, complex, but is becoming recurrent in recent years. In this work we present the VirtualECare project, an intelligent multiagent system able to monitor, interact and serve its customers, in need of care services. In last year’s there has been a substantially increase on the number of people needed of intensive care, especially among the elderly, a phenomenon that is related to population ageing. However, this is becoming not exclusive of the elderly, as diseases like obesity, diabetes and blood pressure have been increasing among young adults. This is a new reality that needs to be dealt by the health sector, particularly by the public one. Given this scenario, the importance of finding new and cost effective ways for health care delivery are of particular importance, especially when it is believed that they should not be removed from their natural “habitat”. Following this line of thinking, the VirtualECare project will be presented, like similar ones that preceded it. On the other hand, this is a growing interest in combining the advances in information society ‐ computing, telecommunications and presentation – in order to create Group Decision Support Systems (GDSSs). Indeed, the new economy, along with increased competition in today’s complex business environments, takes the companies to seek complementarities in order to increase competitiveness and reduce risks. Under these settings, planning takes a major role in a company life. However, effective planning depends on the generation and analysis of ideas (innovative or not) and, as a result, the idea generation and management processes are crucial. In particular if is believed that the use of GDSS in the healthcare arena will allow professionals to achieve better results in the analysis of one’s Electronically Clinical Profile (ECP). This achievement is vital, regarding the explosion of knowledge and skills, together with the need to use limited resources and get the expected outcomes.Hoje em dia, o Trabalho Colaborativo desempenha um papel deveras importante na maioria das organizações, especialmente em áreas em que decisões têm de ser tomadas. No entanto, e muito embora comece a ser recorrente, qualquer decisão que envolva um grupo colectivo de decisores é, por si só, complexa. Nesta tese apresenta‐se o projecto VirtualECare, um sistema inteligente multi‐agente capaz de monitorar, interagir e servir os seus utilizadores, com necessidades de cuidados de saúde. Nos últimos anos têm‐se verificado um aumento substancial no número de pessoas necessitadas de cuidados intensivos, especialmente entre a população mais envelhecida, um fenómeno directamente relacionado com o envelhecimento gradual da população. No entanto, esta é uma problemática que começa a deixar de estar exclusivamente associada aos idosos, uma vez que, doenças como a obesidade, diabetes e a pressão arterial têm vindo a aumentar junto dos, assim chamados, jovens adultos. Esta é uma nova realidade com a qual o sector da saúde necessita de lidar, especialmente o sector público. Apresentados estes cenários, a importância de encontrar novas formas, mais eficazes ao nível dos custos, de providenciar cuidados de saúde, a quem deles necessita, torna‐se ainda mais premente, especialmente quando acreditamos que estes não devem ser deslocalizados do seu “habitat” natural. Seguindo esta linha de raciocínio, vamos apresentar o projecto VirtualECare, bem como similares que o precederam. Recentemente tem‐se vindo a assistir a um interesse crescente em combinar os avanços na, assim chamada, sociedade da informação – computação, telecomunicações e apresentação – de forma a se criarem Sistemas de Apoio à Decisão em Grupo (GDSS). Na realidade, a nova economia, associada ao elevado crescimento da competitividade do, já de si, complexo mundo empresarial, provoca a procura, por parte das empresas e/ou instituições, de outras que as possam complementar para assim se poderem tornar mais competitivas e reduzir os riscos assumidos. Neste cenário, o planeamento assume um papel da maior importância na vida de uma empresa. No entanto, um planeamento eficaz depende da geração e posterior análise de ideias (inovativas ou não) e, como resultado, o processo de geração e análise de ideias também se torna crucial. O nosso objectivo é aplicar os já apresentados GDSS a uma nova área. É de esperar que o uso de GDSS na área da prestação de cuidados de saúde irá permitir que os seus profissionais obtenham melhores e mais imediatos resultados na análise de um qualquer Processo Clínico Electrónico (ECP), sendo este um factor crucial, tendo em conta a explosão de conhecimento e técnicas conjugadas com a necessidade de melhor se utilizar os recursos existentes

    Point-of-care diagnostics with digital microscopy and artificial intelligence

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    The lack of access to diagnostics is a global problem which causes underdiagnosis of various common and treatable diseases. In certain areas, the access to laboratory services and medical experts is extremely limited, such as in sub-Saharan Africa, with often less than one practising pathologist per one million inhabitants. Annually, hundreds of millions of microscopy samples are analysed to diagnose e.g. infectious diseases and cancers, but the need for more is significant. During the last decade, technological advancements and reduced prices of optical components have enabled the construction of inexpensive, portable devices for digitization of microscopy samples; a procedure traditionally limited to well-equipped laboratories with expensive high-end equipment. By allowing digitization of samples directly at the point of care (POC), advanced digital diagnostic techniques, such as the analysis of samples with medical ‘artificial intelligence’ (AI) algorithms, can be utilized also outside high-end laboratories – which is precisely where the need for improved diagnostics is often most significant. The aim of this thesis is to study how low-cost, POC digital microscopy, supported by automatized digital image analysis and AI can be applied for routine microscopy diagnostics with an emphasis on potential areas of application in low-resource settings. We describe, implement and evaluate various techniques for POC digitization and analysis of samples using both visual methods and digital algorithms. Specifically, we evaluate the technologies for the analysis of breast cancer tissue samples (assessment of hormone receptor expression), intraoperative samples from cancer surgeries (detection of metastases in lymph node frozen sections), cytological samples (digital Pap smear screening) and parasitological samples (diagnostics of neglected tropical diseases). Our results show how the digitization of a variety of routine microscopy samples is feasible using systems suitable POC usage with sufficient image quality for diagnostic applications. Furthermore, the findings demonstrate how digital methods, based on computer vision and AI, can be utilized to facilitate the sample analysis process to e.g. quantify tissue stains and detect atypical cells and infectious pathogens in the samples with levels of accuracy comparable to conventional methods. In conclusion, our findings show how technological advancements can be leveraged to create general-purpose digital microscopy diagnostic platforms, which are implementable and feasible to use for diagnostic purposes at the POC. This allows the utilization of modern digital algorithms and AI to aid in analysis of samples and facilitate the diagnostic process by automatically extracting information from the digital samples. These findings are important steps in the effort to develop novel diagnostic technologies which are usable also in areas without access to high-end laboratories, and the technologies described here are also likely to be applicable for diagnostics of other diseases which are currently diagnosed with light microscopy.Bristande åtkomst till medicinsk diagnostik är ett signifikant globalt problem som resulterar i att många vanliga, behandlingsbara sjukdomar förblir underdiagnostiserade. I vissa områden är tillgängligheten av laboratorietjänster och medicinisk personal kraftigt begränsad, liksom exempelvis i subsahariska Afrika där det totala antalet patologer ofta är lägre än en per miljoner invånare. Under det senaste decenniet har den tekniska utvecklingen möjliggjort utvecklingen av portabla, förmånliga instrument för att digitalisera biologiska prov även i fältmiljö; något som traditionellt begränsats till högklassiga laboratorier på grund av kravet på avancerad och dyr teknik. Genom att möjliggöra patientnära (’point of care’) digitalisering av prov kan avancerade digitala metoder, som provanalys med ’artificiell intelligens’, tillämpas även i fältmiljö – dvs. där behovet av förbättrad diagnostik är störst. Målet med avhandlingen är att undersöka hur förmånlig, patientnära digitalmikroskopi, kombinerat med digital bildanalys och artificiell intelligens, kan tillämpas för att effektivera rutinmässig mikroskopidiagnostik med tyngdpunkt på eventuella användningsområden i lågresursmiljöer. I arbetet beskriver, implementerar och utvärderar vi olika metoder för patientnära digitalisering av mikroskopiprov och analys av proven både visuellt och med automatiserade, digitala metoder. Arbetet är uppdelat i olika områden som undersöker teknologin för olika användningsområden. Dessa är: 1) onkologisk vävnadspatologi (bestämning av hormonreceptorstatus), 2) analys av intraoperativa vävnadsprov (fryssnitt för detektion av metastaser), 3) analys av cytologiska cellprov (Papa-prov) samt 4) diagnostik av de vanligaste tropiska parasitsjukdomarna (’neglected tropical diseases’). Resultaten visar hur digitaliseringen av mikroskopiprov är möjlig med miniatyriserade digitalmikroskop som lämpar sig för användning i fältmiljö, med en tillräcklig bildkvalitet för medicinsk diagnostik. Utöver detta kan provanalysen effektiveras med hjälp av automatiserad digital bildanalys, för att ex. mäta nivåer av vävnadsfärger samt identifiera premaligna cellförändringar samt parasiter i proven. Sammanfattningsvis tyder resultaten på att metoderna här är lämpliga för patientnära mikroskopidiagnostik av ett flertal olika sjukdomar. Genom att tillämpa moderna digitala bildanalysmetoder kan provanalysen automatiseras och effektiveras. Resultaten är betydande steg i utvecklingen av digitaldiagnostiska metoder som är användbara även i områden utan tillgång till högklassig laboratorieinfrastruktur. Utöver detta är metoderna beskrivna här sannolikt även möjliga att tillämpa för diagnostik av ett flertal övriga sjukdomar vars diagnostik för tillfället baserar sig på ljusmikroskopi

    Garbling Schemes and Applications

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    The topic of this thesis is garbling schemes and their applications. A garbling scheme is a set of algorithms for realizing secure two-party computation. A party called a client possesses a private algorithm as well as a private input and would like to compute the algorithm with this input. However, the client might not have enough computational resources to evaluate the function with the input on his own. The client outsources the computation to another party, called an evaluator. Since the client wants to protect the algorithm and the input, he cannot just send the algorithm and the input to the evaluator. With a garbling scheme, the client can protect the privacy of the algorithm, the input and possibly also the privacy of the output. The increase in network-based applications has arisen concerns about the privacy of user data. Therefore, privacy-preserving or privacy-enhancing techniques have gained interest in recent research. Garbling schemes seem to be an ideal solution for privacy-preserving applications. First of all, secure garbling schemes hide the algorithm and its input. Secondly, garbling schemes are known to have efficient implementations. In this thesis, we propose two applications utilizing garbling schemes. The first application provides privacy-preserving electronic surveillance. The second application extends electronic surveillance to more versatile monitoring, including also health telemetry. This kind of application would be ideal for assisted living services. In this work, we also present theoretical results related to garbling schemes. We present several new security definitions for garbling schemes which are of practical use. Traditionally, the same garbled algorithm can be evaluated once with garbled input. In applications, the same function is often evaluated several times with different inputs. Recently, a solution based on fully homomorphic encryption provides arbitrarily reusable garbling schemes. The disadvantage in this approach is that the arbitrary reuse cannot be efficiently implemented due to the inefficiency of fully homomorphic encryption. We propose an alternative approach. Instead of arbitrary reusability, the same garbled algorithm could be used a limited number of times. This gives us a set of new security classes for garbling schemes. We prove several relations between new and established security definitions. As a result, we obtain a complex hierarchy which can be represented as a product of three directed graphs. The three graphs in turn represent the different flavors of security: the security notion, the security model and the level of reusability. In addition to defining new security classes, we improve the definition of side-information function, which has a central role in defining the security of a garbling scheme. The information allowed to be leaked by the garbled algorithm and the garbled input depend on the representation of the algorithm. The established definition of side-information models the side-information of circuits perfectly but does not model side-information of Turing machines as well. The established model requires that the length of the argument, the length of the final result and the length of the function can be efficiently computable from the side-information function. Moreover, the side-information depends only on the function. In other words, the length of the argument, the length of the final result and the length of the function should only depend on the function. For circuits this is a natural requirement since the number of input wires tells the size of the argument, the number of output wires tells the size of the final result and the number of gates and wires tell the size of the function. On the other hand, the description of a Turing machine does not set any limitation to the size of the argument. Therefore, side-information that depends only on the function cannot provide information about the length of the argument. To tackle this problem, we extend the model of side-information so that side-information depends on both the function and the argument. The new model of side information allows us to define new security classes. We show that the old security classes are compatible with the new model of side-information. We also prove relations between the new security classes.Tämä väitöskirja käsittelee garblausskeemoja ja niiden sovelluksia. Garblausskeema on työkalu, jota käytetään turvallisen kahden osapuolen laskennan toteuttamiseen. Asiakas pitää hallussaan yksityistä algoritmia ja sen yksityistä syötettä, joilla hän haluaisi suorittaa tietyn laskennan. Asiakkaalla ei välttämättä ole riittävästi laskentatehoa, minkä vuoksi hän ei pysty suorittamaan laskentaa itse, vaan joutuu ulkoistamaan laskennan toiselle osapuolelle, palvelimelle. Koska asiakas tahtoo suojella algoritmiaan ja syötettään, hän ei voi vain lähettää niitä palvelimen laskettavaksi. Asiakas pystyy suojelemaan syötteensä ja algoritminsa yksityisyyttä käyttämällä garblausskeemaa. Verkkopohjaisten sovellusten kasvu on herättänyt huolta käyttäjien datan yksityisyyden turvasta. Siksi yksityisyyden säilyttävien tai yksityisyyden suojaa lisäävien tekniikoiden tutkimus on saanut huomiota. Garblaustekniikan avulla voidaan suojata sekä syöte että algoritmi. Lisäksi garblaukselle tiedetään olevan useita tehokkaita toteutuksia. Näiden syiden vuoksi garblausskeemat ovat houkutteleva tekniikka käytettäväksi yksityisyyden säilyttävien sovellusten toteutuksessa. Tässä työssä esittelemme kaksi sovellusta, jotka hyödyntävät garblaustekniikkaa. Näistä ensimmäinen on yksityisyyden säilyttävä sähköinen seuranta. Toinen sovellus laajentaa seurantaa monipuolisempaan monitorointiin, kuten terveyden kaukoseurantaan. Tästä voi olla hyötyä etenkin kotihoidon palveluille. Tässä työssä esitämme myös teoreettisia tuloksia garblausskeemoihin liittyen. Esitämme garblausskeemoille uusia turvallisuusmääritelmiä, joiden tarve kumpuaa käytännön sovelluksista. Perinteisen määritelmän mukaan samaa garblattua algoritmia voi käyttää vain yhdellä garblatulla syötteellä laskemiseen. Käytännössä kuitenkin samaa algoritmia käytetään usean eri syötteen evaluoimiseen. Hiljattain on esitetty tähän ongelmaan ratkaisu, joka perustuu täysin homomorfiseen salaukseen. Tämän ratkaisun ansiosta samaa garblattua algoritmia voi turvallisesti käyttää mielivaltaisen monta kertaa. Ratkaisun haittapuoli kuitenkin on, ettei sille ole tiedossa tehokasta toteutusta, sillä täysin homomorfiseen salaukseen ei ole vielä onnistuttu löytämään sellaista. Esitämme vaihtoehtoisen näkökulman: sen sijaan, että samaa garblattua algoritmia voisi käyttää mielivaltaisen monta kertaa, sitä voikin käyttää vain tietyn, ennalta rajatun määrän kertoja. Tämä näkökulman avulla voidaan määritellä lukuisia uusia turvallisuusluokkia. Todistamme useita relaatioita uusien ja vanhojen turvallisuusmääritelmien välillä. Relaatioiden avulla garblausskeemojen turvallisuusluokille saadaan muodostettua hierarkia, joka koostuu kolmesta komponentista. Tieto, joka paljastuu garblatusta algoritmista tai garblatusta syötteestä riippuu siitä, millaisessa muodossa algoritmi on esitetty, kutsutaan sivutiedoksi. Vakiintunut määritelmä mallintaa loogisen piiriin liittyvää sivutietoa täydellisesti, mutta ei yhtä hyvin Turingin koneeseen liittyvää sivutietoa. Tämä johtuu siitä, että jokainen yksittäinen looginen piiri asettaa syötteensä pituudelle rajan, mutta yksittäisellä Turingin koneella vastaavanlaista rajoitusta ei ole. Parannamme sivutiedon määritelmää, jolloin tämä ongelma poistuu. Uudenlaisen sivutiedon avulla voidaan määritellä uusia turvallisuusluokkia. Osoitamme, että vanhat turvallisuusluokat voidaan esittää uudenkin sivutiedon avulla. Todistamme myös relaatioita uusien luokkien välillä.Siirretty Doriast
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