SoK: Plausibly Deniable Storage

Data privacy is critical in instilling trust and empowering the societal pacts of modern technology-driven democracies. Unfortunately, it is under continuous attack by overreaching or outright oppressive governments, including some of the world\u27s oldest democracies. Increasingly-intrusive anti-encryption laws severely limit the ability of standard encryption to protect privacy. New defense mechanisms are needed. Plausible deniability (PD) is a powerful property, enabling users to hide the existence of sensitive information in a system under direct inspection by adversaries. Popular encrypted storage systems such as TrueCrypt and other research efforts have attempted to also provide plausible deniability. Unfortunately, these efforts have often operated under less well-defined assumptions and adversarial models. Careful analyses often uncover not only high overheads but also outright security compromise. Further, our understanding of adversaries, the underlying storage technologies, as well as the available plausible deniable solutions have evolved dramatically in the past two decades. The main goal of this work is to systematize this knowledge. It aims to: - identify key PD properties, requirements, and approaches; - present a direly-needed unified framework for evaluating security and performance; - explore the challenges arising from the critical interplay between PD and modern system layered stacks; - propose a new trace-oriented PD paradigm, able to decouple security guarantees from the underlying systems and thus ensure a higher level of flexibility and security independent of the technology stack. This work is meant also as a trusted guide for system and security practitioners around the major challenges in understanding, designing, and implementing plausible deniability into new or existing systems

Capacity-Achieving Coding Mechanisms: Spatial Coupling and Group Symmetries

The broad theme of this work is in constructing optimal transmission mechanisms for a wide variety of communication systems. In particular, this dissertation provides a proof of threshold saturation for spatially-coupled codes, low-complexity capacity-achieving coding schemes for side-information problems, a proof that Reed-Muller and primitive narrow-sense BCH codes achieve capacity on erasure channels, and a mathematical framework to design delay sensitive communication systems. Spatially-coupled codes are a class of codes on graphs that are shown to achieve capacity universally over binary symmetric memoryless channels (BMS) under belief-propagation decoder. The underlying phenomenon behind spatial coupling, known as “threshold saturation via spatial coupling”, turns out to be general and this technique has been applied to a wide variety of systems. In this work, a proof of the threshold saturation phenomenon is provided for irregular low-density parity-check (LDPC) and low-density generator-matrix (LDGM) ensembles on BMS channels. This proof is far simpler than published alternative proofs and it remains as the only technique to handle irregular and LDGM codes. Also, low-complexity capacity-achieving codes are constructed for three coding problems via spatial coupling: 1) rate distortion with side-information, 2) channel coding with side-information, and 3) write-once memory system. All these schemes are based on spatially coupling compound LDGM/LDPC ensembles. Reed-Muller and Bose-Chaudhuri-Hocquengham (BCH) are well-known algebraic codes introduced more than 50 years ago. While these codes are studied extensively in the literature it wasn’t known whether these codes achieve capacity. This work introduces a technique to show that Reed-Muller and primitive narrow-sense BCH codes achieve capacity on erasure channels under maximum a posteriori (MAP) decoding. Instead of relying on the weight enumerators or other precise details of these codes, this technique requires that these codes have highly symmetric permutation groups. In fact, any sequence of linear codes with increasing blocklengths whose rates converge to a number between 0 and 1, and whose permutation groups are doubly transitive achieve capacity on erasure channels under bit-MAP decoding. This pro-vides a rare example in information theory where symmetry alone is sufficient to achieve capacity. While the channel capacity provides a useful benchmark for practical design, communication systems of the day also demand small latency and other link layer metrics. Such delay sensitive communication systems are studied in this work, where a mathematical framework is developed to provide insights into the optimal design of these systems

Study On Endurance Of Flash Memory Ssds

Flash memory promises to revolutionize storage systems because of its massive performance gains, ruggedness, large decrease in power usage and physical space requirements, but it is not a direct replacement for magnetic hard disks. Flash memory possesses fundamentally different characteristics and in order to fully utilize the positive aspects of flash memory, we must engineer around its unique limitations. The primary limitations are lack of in-place updates, the asymmetry between the sizes of the write and erase operations, and the limited endurance of flash memory cells. This leads to the need for efficient methods for block cleaning, combating write amplification and performing wear leveling. These are fundamental attributes of flash memory and will always need to be understood and efficiently managed to produce an efficient and high performance storage system. Our goal in this work is to provide analysis and algorithms for efficiently managing data storage for endurance in flash memory. We present update codes, a class of floating codes, which encodes data updates as flash memory cell increments that results in reduced block erases and longer lifespan of flash memory, and provides a new algorithm for constructing optimal floating codes. We also analyze the theoretically possible limits of write amplification reduction and minimization by using offline workloads. We give an estimation of the minimal write amplification by a workload decomposition algorithm and find that write amplification can be pushed to zero with relatively low over-provisioning. Additionally, we give simple, efficient and practical algorithms that are effective in reducing write amplification and performing wear leveling. Finally, we present a quantitative model of wear levels in flash memory by constructing a difference equation that gives erase counts of a block with workload, wear leveling strategy and SSD configuration as parameters

The cause, development and outcome of word-of-mouth marketing: with particular reference to WOM volume, valence and the modeling of viral marketing

Viral marketing is a form of online word-of-mouth (WOM) communication in which individuals are encouraged to pass on promotional messages through social websites. With the growing popularity of online social websites, viral marketing has increasingly garnered attention of marketers and marketing researchers alike. The two most important WOM attributes highlighted in the extant literature are volume and valence. This thesis looked into the cause, development and outcome of WOM marketing and provided computational models for forecasting the development of WOM volume and valence of viral marketing in social websites. With the data extracted from large-scale web-crawling activities, through a series of computer simulation experiments comparable to social websites, the author developed models to predict WOM volume and valence in viral marketing. The model for predicting WOM volume in viral marketing used theories of network topologies. The model for predicting WOM valence in viral marketing used an artificial neural network model. The author discussed the insights from the findings and suggested viral marketing strategies to optimize the performance of WOM volume and valence in social websites. A key contribution of this thesis is the new approaches of modeling and data collection for WOM volume and valance forecasting in viral marketing

The application of social media for marketing strategies in pharma healthcare

Digital is transforming the way the world does business, and healthcare is no exception. The COVID-19 outbreak has had a significant impact on internet use and accelerated the digital transition worldwide as well as in Portugal. Social media is the fastest communication network among worldwide people. During the outbreak, the usage of social media platforms increased two times more compared with normal days. With increasing health literacy and access to technology, consumers are becoming more informed and proactive towards health issues and selfmedication, 67% of them are researching health problems and symptoms tracking and 81% conduct online research before making a purchase. This change has expanded communication from offline to the internet. Electronic word-of-mouth communication (eWOM), based on social media, brought more variables to marketing communication and became an interesting field for research considering its communication potential. Indeed, several studies have shown the ability to influence interpersonal communications on products or services in the purchase intention of consumers. As so, in recent years, some authors discussed the impact of eWOM on consumer online purchasing decisions; however, the literature is still relatively nascent regarding the Pharmaceutical Industry and the self-medication segment market of Over-the-Counter medicines (OTC). Pharmaceutical companies must be aware of this paradigm change: the patient is an indispensable and active stakeholder in the present and future of healthcare, besides the physician and the payer. Pharma marketing may be moving into a more digitalized space, but there is still room for improvement, especially when it comes to social media there is an unexploited territory for pharma marketers as most pharmaceutical companies are not yet to answer these consumers habits with an effective digital presence. The current research aims to study the application of Social Media platforms for marketing or communication purposes in pharma healthcare in Portugal.digital está a transformar a forma como os negócios se fazem no mundo, e a saúde não é exceção. A pandemia de COVID-19 teve um impacto significativo na utilização da Internet e acelerou a transição digital a nível mundial, incluindo Portugal. Com o aumento da literacia em saúde e o acesso à tecnologia, os consumidores estão a tornar-se mais informados e proativos em relação aos seus cuidados com a saúde e à automedicação, 67% destes pesquisam problemas de saúde e sintomas e 81% realizam pesquisas online antes de fazer uma compra. Esta mudança de comportamento expandiu a comunicação do offline para a Internet. A comunicação electronic word-of-mouth (eWOM), baseada nos media sociais, envolve mais variáveis para a comunicação de marketing; nos últimos anos, alguns autores discutiram o impacto do eWOM nas decisões de compra do consumidor online; entretanto, a literatura ainda é relativamente incipiente no que diz respeito à Indústria Farmacêutica e ao segmento de automedicação do mercado de medicamentos de venda livre (OTC). As empresas farmacêuticas devem estar atentas a esta mudança de paradigma: o paciente é uma parte indispensável e ativa no presente e no futuro da área da saúde, além do médico e do pagador. O marketing farmacêutico está a evoluir para a digitalização, mas ainda há espaço para melhorias, especialmente no âmbito das redes sociais que ainda são um território pouco explorado pelos profissionais de marketing farmacêutico. A maioria das empresas farmacêuticas ainda não se adaptou a estes hábitos de consumo com uma presença digital eficaz. A presente investigação pretende identificar a aplicação de plataformas de redes sociais para efeitos de marketing ou comunicação na área da indústria farmacêutica em Portugal

Forecasting: theory and practice

Forecasting has always been in the forefront of decision making and planning. The uncertainty that surrounds the future is both exciting and challenging, with individuals and organisations seeking to minimise risks and maximise utilities. The lack of a free-lunch theorem implies the need for a diverse set of forecasting methods to tackle an array of applications. This unique article provides a non-systematic review of the theory and the practice of forecasting. We offer a wide range of theoretical, state-of-the-art models, methods, principles, and approaches to prepare, produce, organise, and evaluate forecasts. We then demonstrate how such theoretical concepts are applied in a variety of real-life contexts, including operations, economics, finance, energy, environment, and social good. We do not claim that this review is an exhaustive list of methods and applications. The list was compiled based on the expertise and interests of the authors. However, we wish that our encyclopedic presentation will offer a point of reference for the rich work that has been undertaken over the last decades, with some key insights for the future of the forecasting theory and practice

Undergraduate and Graduate Course Descriptions, 2016 Fall

Wright State University undergraduate and graduate course descriptions from Fall 2016

Undergraduate and Graduate Course Descriptions, 2017 Fall

Wright State University undergraduate and graduate course descriptions from Fall 2017

Undergraduate and Graduate Course Descriptions, 2017 Fall

Wright State University undergraduate and graduate course descriptions from Fall 2017