Robust and cheating-resilient power auctioning on Resource Constrained Smart Micro-Grids

The principle of Continuous Double Auctioning (CDA) is known to provide an efficient way of matching supply and demand among distributed selfish participants with limited information. However, the literature indicates that the classic CDA algorithms developed for grid-like applications are centralised and insensitive to the processing resources capacity, which poses a hindrance for their application on resource constrained, smart micro-grids (RCSMG). A RCSMG loosely describes a micro-grid with distributed generators and demand controlled by selfish participants with limited information, power storage capacity and low literacy, communicate over an unreliable infrastructure burdened by limited bandwidth and low computational power of devices. In this thesis, we design and evaluate a CDA algorithm for power allocation in a RCSMG. Specifically, we offer the following contributions towards power auctioning on RCSMGs. First, we extend the original CDA scheme to enable decentralised auctioning. We do this by integrating a token-based, mutual-exclusion (MUTEX) distributive primitive, that ensures the CDA operates at a reasonably efficient time and message complexity of O(N) and O(logN) respectively, per critical section invocation (auction market execution). Our CDA algorithm scales better and avoids the single point of failure problem associated with centralised CDAs (which could be used to adversarially provoke a break-down of the grid marketing mechanism). In addition, the decentralised approach in our algorithm can help eliminate privacy and security concerns associated with centralised CDAs. Second, to handle CDA performance issues due to malfunctioning devices on an unreliable network (such as a lossy network), we extend our proposed CDA scheme to ensure robustness to failure. Using node redundancy, we modify the MUTEX protocol supporting our CDA algorithm to handle fail-stop and some Byzantine type faults of sites. This yields a time complexity of O(N), where N is number of cluster-head nodes; and message complexity of O((logN)+W) time, where W is the number of check-pointing messages. These results indicate that it is possible to add fault tolerance to a decentralised CDA, which guarantees continued participation in the auction while retaining reasonable performance overheads. In addition, we propose a decentralised consumption scheduling scheme that complements the auctioning scheme in guaranteeing successful power allocation within the RCSMG. Third, since grid participants are self-interested we must consider the issue of power theft that is provoked when participants cheat. We propose threat models centred on cheating attacks aimed at foiling the extended CDA scheme. More specifically, we focus on the Victim Strategy Downgrade; Collusion by Dynamic Strategy Change, Profiling with Market Prediction; and Strategy Manipulation cheating attacks, which are carried out by internal adversaries (auction participants). Internal adversaries are participants who want to get more benefits but have no interest in provoking a breakdown of the grid. However, their behaviour is dangerous because it could result in a breakdown of the grid. Fourth, to mitigate these cheating attacks, we propose an exception handling (EH) scheme, where sentinel agents use allocative efficiency and message overheads to detect and mitigate cheating forms. Sentinel agents are tasked to monitor trading agents to detect cheating and reprimand the misbehaving participant. Overall, message complexity expected in light demand is O(nLogN). The detection and resolution algorithm is expected to run in linear time complexity O(M). Overall, the main aim of our study is achieved by designing a resilient and cheating-free CDA algorithm that is scalable and performs well on resource constrained micro-grids. With the growing popularity of the CDA and its resource allocation applications, specifically to low resourced micro-grids, this thesis highlights further avenues for future research. First, we intend to extend the decentralised CDA algorithm to allow for participants’ mobile phones to connect (reconnect) at different shared smart meters. Such mobility should guarantee the desired CDA properties, the reliability and adequate security. Secondly, we seek to develop a simulation of the decentralised CDA based on the formal proofs presented in this thesis. Such a simulation platform can be used for future studies that involve decentralised CDAs. Third, we seek to find an optimal and efficient way in which the decentralised CDA and the scheduling algorithm can be integrated and deployed in a low resourced, smart micro-grid. Such an integration is important for system developers interested in exploiting the benefits of the two schemes while maintaining system efficiency. Forth, we aim to improve on the cheating detection and mitigation mechanism by developing an intrusion tolerance protocol. Such a scheme will allow continued auctioning in the presence of cheating attacks while incurring low performance overheads for applicability in a RCSMG

Modulation of electrical stimulation applied to human physiology and clinical diagnostic

The use, manipulation and application of electrical currents, as a controlled interference mechanism in the human body system, is currently a strong source of motivation to researchers in areas such as clinical, sports, neuroscience, amongst others. In electrical stimulation (ES), the current applied to tissue is traditionally controlled concerning stimulation amplitude, frequency and pulse-width. The main drawbacks of the transcutaneous ES are the rapid fatigue induction and the high discomfort induced by the non-selective activation of nervous fibers. There are, however, electrophysiological parameters whose response, like the response to different stimulation waveforms, polarity or a personalized charge control, is still unknown. The study of the following questions is of great importance: What is the physiological effect of the electric pulse parametrization concerning charge, waveform and polarity? Does the effect change with the clinical condition of the subjects? The parametrization influence on muscle recruitment can retard fatigue onset? Can parametrization enable fiber selectivity, optimizing the motor fibers recruitment rather than the nervous fibers, reducing contraction discomfort? Current hardware solutions lack flexibility at the level of stimulation control and physiological response assessment. To answer these questions, a miniaturized, portable and wireless controlled device with ES functions and full integration with a generic biosignals acquisition platform has been created. Hardware was also developed to provide complete freedom for controlling the applied current with respect to the waveform, polarity, frequency, amplitude, pulse-width and duration. The impact of the methodologies developed is successfully applied and evaluated in the contexts of fundamental electrophysiology, psycho-motor rehabilitation and neuromuscular disorders diagnosis. This PhD project was carried out in the Physics Department of Faculty of Sciences and Technology (FCT-UNL), in straight collaboration with PLUX - Wireless Biosignals S.A. company and co-funded by the Foundation for Science and Technology.Fundação para a Ciência e Tecnologia (FCT); PLUX - Wireless Biosignals, S.A.; FCT-UNL- CEFITE

Principles of Security and Trust: 7th International Conference, POST 2018, Held as Part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2018, Thessaloniki, Greece, April 14-20, 2018, Proceedings

authentication; computer science; computer software selection and evaluation; cryptography; data privacy; formal logic; formal methods; formal specification; internet; privacy; program compilers; programming languages; security analysis; security systems; semantics; separation logic; software engineering; specifications; verification; world wide we

Konzepte für Datensicherheit und Datenschutz in mobilen Anwendungen

Smart Devices und insbesondere Smartphones nehmen eine immer wichtigere Rolle in unserem Leben ein. Aufgrund einer kontinuierlich anwachsenden Akkulaufzeit können diese Geräte nahezu ununterbrochen mitgeführt und genutzt werden. Zusätzlich sorgen stetig günstiger werdende Mobilfunktarife und ansteigende Datenraten dafür, dass den Nutzern mit diesen Geräten eine immerwährende Verbindung zum Internet zur Verfügung steht. Smart Devices sind dadurch nicht mehr reine Kommunikationsmittel sondern ebenfalls Informationsquellen. Darüber hinaus gibt es eine Vielzahl an Anwendungen von Drittanbietern für diese Geräte. Dank der darin verbauten Sensoren, können darauf beispielsweise ortsbasierte Anwendungen, Gesundheitsanwendungen oder Anwendungen für die Industrie 4.0 ausgeführt werden, um nur einige zu nennen. Solche Anwendungen stellen allerdings nicht nur ein großes Nutzen-, sondern zu gleich ein immenses Gefahrenpotential dar. Über die Sensoren können die unterschiedlichsten Kontextdaten erfasst und relativ präzise Rückschlüsse auf den Nutzer gezogen werden. Daher sollte bei diesen Geräten ein besonderes Augenmerk auf die Datensicherheit und insbesondere auf den Datenschutz gelegt werden. Betrachtet man allerdings die bestehenden Datensicherheits- und Datenschutzkomponenten in den aktuell vorherrschenden mobilen Plattformen, so fällt auf, dass keine der Plattformen die speziellen Anforderungen an ein mobiles Datensicherheits- und Datenschutzsystem zufriedenstellend erfüllt. Aus diesem Grund steht im Zentrum der vorliegende Arbeit die Konzeption und Umsetzung neuartiger Datensicherheits- und Datenschutzkonzepte für mobile Anwendungen. Hierfür werden die folgenden fünf Forschungsbeiträge erbracht: [FB1] Bestehende Datensicherheits- und Datenschutzkonzepte werden analysiert, um deren Schwachstellen zu identifizieren. [FB2] Ein kontextsensitives Berechtigungsmodell wird erstellt. [FB3] Das Berechtigungsmodell wird in einem flexiblen Datenschutzsystem konzeptionell eingebettet und anschließend implementiert. [FB4] Das Datenschutzsystem wird zu einem holistischen Sicherheitssystem erweitert. [FB5] Das daraus entstandene holistische Sicherheitssystem wird evaluiert. Um die Forschungsziele zu erreichen, wird mit dem Privacy Policy Model (PPM) ein gänzlich neues Modell zur Formulierung von feingranularen Berechtigungsregeln eingeführt, die es dem Nutzer ermöglichen, je nach Bedarf, einzelne Funktionseinheiten einer Anwendung zu deaktivieren, um dadurch die Zugriffsrechte der Anwendung einzuschränken. Zusätzlich kann der Nutzer auch die Genauigkeit der Daten, die der Anwendung zur Verfügung gestellt werden, reduzieren. Das PPM wird in der Privacy Policy Platform (PMP) implementiert. Die PMP ist ein Berechtigungssystem, das nicht nur für die Einhaltung der Datenschutzrichtlinien sorgt, sondern auch einige der Schutzziele der Datensicherheit erfüllt. Für die PMP werden mehrere Implementierungsstrategien diskutiert und deren Vor- und Nachteile gegeneinander abgewogen. Um neben den Datenschutz auch die Datensicherheit gewährleisten zu können, wird die PMP um den Secure Data Container (SDC) erweitert. Mit dem SDC können sensible Daten sicher gespeichert und zwischen Anwendungen ausgetauscht werden. Die Anwendbarkeit der PMP und des SDCs wird an Praxisbeispielen aus vier unterschiedlichen Domänen (ortsbasierte Anwendungen, Gesundheitsanwendungen, Anwendungen in der Industrie 4.0 und Anwendungen für das Internet der Dinge) demonstriert. Bei dieser Analyse zeigt sich, dass die Kombination aus PMP und SDC nicht nur sämtliche Schutzziele, die im Rahmen der vorliegenden Arbeit relevant sind und sich am ISO-Standard ISO/IEC 27000:2009 orientieren, erfüllt, sondern darüber hinaus sehr performant ist. Durch die Verwendung der PMP und des SDCs kann der Akkuverbrauch von Anwendungen halbiert werden

An investigation of customers' loyalty to social commerce websites

The emergence of web 2.0 has brought new applications that have played a significant role in extending electronic commerce websites with social commerce functionality. Social commerce is a relatively new extension of B2C electronic commerce where customers purchase products and services online with the existence of social cues in the websites (such as reviews, recommendations and sharing). In this thesis, the research examines those websites which fulfil the role of a traditional eCommerce website but have also had added to them a range of social interaction features. There has been little research in the area of customer loyalty to social commerce websites. Drawing upon theories of social presence and trust (and the Delone and McLean model of information systems success) this study aims to determine what factors affect customer loyalty to social commerce websites and to develop a framework that helps in investigating those factors. In order to achieve this objective, a quantitative approach was employed. Data was collected from social commerce users in Australia through an online survey. The quantitative survey of online social commerce customers' opinions regarding the measurement items was based on a probability sample of qualified Australian customers of social commerce websites. A stratified random sampling was used with all Australian states that constitute the strata of the Australian population. The population of the study consisted of male and female customers of multiple social commerce websites who live in Australia. Nine hundred and ninety-seven surveys were collected. After screening the data, 797 surveys were ready to be analysed. An analysis was performed using a Partial Least Squares Structural Equation Modelling (PLS-SEM) technique with SmartPLS 3 software. The findings demonstrated that reputation, satisfaction, word-of-mouth, and social presence positively contribute to explaining the variance in trust. In contrast, communication, and online shopping experience did not contribute to explain the variance in trust. Examining the relevance of significant relationships between the six exogenous constructs with trust, the results showed that satisfaction, reputation, word-of-mouth, and social presence carried comparable weights in impacting trust with path coefficients that were different in magnitude. The results imply that satisfaction, reputation, word-of-mouth and social presence are important factors to predict trust rather than communication, and online shopping experience. Among the exogenous constructs as predictors of satisfaction, service quality and information quality influence satisfaction were the most significant, whereas system quality did not influence satisfaction significantly. Finally, this study found that satisfaction, trust and social presence have a significant influence on customer loyalty to a social commerce website. This study contributes to the social commerce literature through a theoretical framework that shows how the loyalty of customers can be generated in social commerce websites. In addition, it is expected that this study will help businesses to have an understanding of how to retain their customers, which will result in higher profits. From a customer perspective, this study will give customers a way to objectively evaluate whether a social commerce site provides quality products and services. Furthermore, the study will motivate businesses to improve their websites, which in turn will provide customers with better website services

Investigating privacy perceptions, attitudes and behaviours of the inflammatory bowel disease online health communities

During their lifetime, people living with Inflammatory Bowel Disease (IBD) may require social support. Over the past 3 decades the internet has provided new opportunities for people living with chronic health conditions to meet virtually to both seek and receive empathetic support from the comfort of their own homes. Furthermore, the prevalence of smart mobile devices and social media platforms has provided individuals with easy to reach, on the go social support to meet their needs. Online support has been recognised as having additional benefits to face to-face support, such as how the asynchronous nature of online communications affords individuals to browse a rich history of previous posts. However, self-disclosed information on the internet is subject to privacy risks. In Law and Sociology, health information is considered to be ‘sensitive’ data; however, there are thousands of individuals living with IBD sharing intimate health information on social media platforms. This thesis explores how people living with IBD perceive their privacy on social media through a dual lens of social privacy and information privacy. A mixed-methods approach was adopted across 3 empirical studies to examine the perceptions, attitudes, and behaviours of people living with IBD and using social media to participate in online health communities. The first study explored how people living with IBD use Facebook, Twitter, and Instagram to engage with online health communities through 38 semi-structured interviews. The findings indicate that each of the platforms shared similar functionality which in turn generally afforded similar therapeutic outcomes. The analysis found evidence to suggest that people’s experiences of each platform was not exclusively as a result of the technical functions of each platform but were combined with their motivations and their previous social interactions. Significantly, this study also drew a distinction in the ways in which people perceive privacy on social media; demonstrating clear understandings of their social privacy boundaries and the actions they take to reduce privacy violations. Conversely, participants demonstrated a low awareness of how their data is collected and used by social media platforms, thus making it difficult for individuals to identify information privacy risks. The second study involved community leaders participating in focus groups to discuss the privacy challenges as well as identifying possible prototypes to support the digital well-being of potentially vulnerable people. Finding that an education-driven approach would be a suitable short-term option to improve people’s understanding, an intervention was developed through Patient and Public Involvement for the third study. The final study involved pre and post web-surveys to digital interventions to assess people’s attitudes towards learning more about online privacy, as well as its impacts on the IBD community. Taken together, this thesis presents new evidence to suggest how individuals use different social media platforms. It also demonstrates how social privacy and information privacy are thought and acted upon in different ways. However, there is some evidence to suggest that over the course of data collection for this PhD 4 (2017-2020) there are changing attitudes towards information privacy and the ways in which people’s health information is used by social media platforms

Investigating privacy perceptions, attitudes and behaviours of the inflammatory bowel disease online health communities

During their lifetime, people living with Inflammatory Bowel Disease (IBD) may require social support. Over the past 3 decades the internet has provided new opportunities for people living with chronic health conditions to meet virtually to both seek and receive empathetic support from the comfort of their own homes. Furthermore, the prevalence of smart mobile devices and social media platforms has provided individuals with easy to reach, on the go social support to meet their needs. Online support has been recognised as having additional benefits to face to-face support, such as how the asynchronous nature of online communications affords individuals to browse a rich history of previous posts. However, self-disclosed information on the internet is subject to privacy risks. In Law and Sociology, health information is considered to be ‘sensitive’ data; however, there are thousands of individuals living with IBD sharing intimate health information on social media platforms. This thesis explores how people living with IBD perceive their privacy on social media through a dual lens of social privacy and information privacy. A mixed-methods approach was adopted across 3 empirical studies to examine the perceptions, attitudes, and behaviours of people living with IBD and using social media to participate in online health communities. The first study explored how people living with IBD use Facebook, Twitter, and Instagram to engage with online health communities through 38 semi-structured interviews. The findings indicate that each of the platforms shared similar functionality which in turn generally afforded similar therapeutic outcomes. The analysis found evidence to suggest that people’s experiences of each platform was not exclusively as a result of the technical functions of each platform but were combined with their motivations and their previous social interactions. Significantly, this study also drew a distinction in the ways in which people perceive privacy on social media; demonstrating clear understandings of their social privacy boundaries and the actions they take to reduce privacy violations. Conversely, participants demonstrated a low awareness of how their data is collected and used by social media platforms, thus making it difficult for individuals to identify information privacy risks. The second study involved community leaders participating in focus groups to discuss the privacy challenges as well as identifying possible prototypes to support the digital well-being of potentially vulnerable people. Finding that an education-driven approach would be a suitable short-term option to improve people’s understanding, an intervention was developed through Patient and Public Involvement for the third study. The final study involved pre and post web-surveys to digital interventions to assess people’s attitudes towards learning more about online privacy, as well as its impacts on the IBD community. Taken together, this thesis presents new evidence to suggest how individuals use different social media platforms. It also demonstrates how social privacy and information privacy are thought and acted upon in different ways. However, there is some evidence to suggest that over the course of data collection for this PhD 4 (2017-2020) there are changing attitudes towards information privacy and the ways in which people’s health information is used by social media platforms