No / With the rapid growth of the scale, complexity, and heterogeneity of Peer-to-Peer (P2P) systems, it has become a great challenge to deal with the peer's network-oblivious traffic and self-organization problems. A potential solution is to deploy servers in appropriate locations. However, due to the unique features and requirements of P2P systems, the traditional placement models cannot yield the desirable service performance. To fill this gap, we propose an efficient server placement model for P2P live streaming systems. Compared to the existing solutions, this model takes the Internet Service Provider (ISP) friendly problem into account and can reduce the cross-network traffic among ISPs. Specifically, we introduce the peers' contribution into the proposed model, which makes it more suitable for P2P live streaming systems. Moreover, we deploy servers based on the theoretical solution subject to practical data and apply them to practical live streaming applications. The experimental results show that this new model can reduce the amount of cross-network traffic and improve the system efficiency, has a better adaptability to Internet environment, and is more suitable for P2P systems than the traditional placement models.

This thesis describes the application of microprocessor based relays with internet communication capabilities in distribution protection systems. The traditional distribution protection system (recloser, sectionalizers) was configured to automatically isolate faulted circuits as well as to reenergize unfaulted loads after a certain number of reclosing operations. Internet Peer-to-Peer communication enables distribution relays to communicate with others connected to the communication network without having a master device. According to the results, the addition of peer-to-peer communication to a traditional distribution protection system significantly enhances its general performance eliminating undesired losses of unfaulted load. Additionally, it reduces outage duration as well as thermal and mechanical stress due to successive re-energizations under faults condition. / Master of Science

The key goal in this work is to enable a flexible ground station that is not constrained to a particular mission or set of hardware. In addition, with the concepts and software produced in this thesis, it will play a significant role in educating engineers and students by providing critical infrastructure and a sandbox for ground station operations. Key pieces of software were developed in this work to create a flexible and robust software-defined ground station. Several digital transmission modes were developed in order to allow communication between the ground station and common amateur radio CubeSats and SmallSats. In order to handle distributed tasks and process at a ground station with multiple servers and controllers, a specialized actor framework was written in Python for ease of use. Actors have the ability to send messages to one another over a network, and they maintain their own memory in order to avoid synchronization problems that come with sharing memory. In addition to the software developed in this work, a novel Peer-to-Peer (P2P) protocol for a network of ground stations is proposed in order to increase coverage and access to spacecraft without requiring centralized server infrastructure. This protocol provides the method to scale the developed software architecture beyond a single ground station. Since the Virginia Tech Ground Station (VTGS) will have many concurrent processes running across multiple servers, it was necessary to apply the actor model in order to simplify the design of the system. The purpose of this thesis is to describe the developed software for the VTGS as well as the P2P protocol for a larger network of ground stations. There are three primary repositories: planck-dsp, gr-vtgs, and pystation. The planck-dsp library and gr-vtgs Out-of-tree (OOT) make up the primary digital signal processing and communications toolboxes, where GNU Radio serves as the scheduler for signal processing blocks used in flow graphs. The pystation module is the extensible software actor framework that connects various systems both locally and remotely. It is also responsible for scheduling and handling ground station requests. While the software was primarily created for the VTGS, it is general enough to apply to other ground station implementations. / Master of Science

No / The surprise advent of the peer-to-peer payment system Bitcoin in 2009 has raised various concerns regarding its relationship to established economic market ideologies. Unlike fiat currencies, Bitcoin is based on open-source software; it is a secure cryptocurrency, traded as an investment between two individuals over the internet, with no bank involvement. Computationally, this is a very innovative solution, but Bitcoin’s popularity has raised a number of security and trust concerns among mainstream economists. With cities and countries, including San Francisco and Germany, using Bitcoin as a unit of account in their financial systems, there is still a lack of understanding and a paucity of models for studying its use, and the role Bitcoin might play in real physical economies. This project tackles these issues by analysing the ramifications of Bitcoin within economic models, by building a computational model of the currency to test its performance in financial market models. The project uses established agent-based modelling techniques to build a decentralised Bitcoin model, which can be ‘plugged into’ existing agent-based models of key economic and financial markets. This allows various metrics to be subjected to critical analysis, gauging the progress of digital economies equipped with Bitcoin usage. This project contributes to the themes of privacy, consent, security and trust in the digital economy and digital technologies, enabling new business models of direct relevance to NEMODE. As computer scientists, we consider Bitcoin from a technical perspective; this contrasts with and complements other current Bitcoin research, and helps document the realizable risks Bitcoin and similar currencies bring to our current economic world. This report outlines a comprehensive collection of risks raised by Bitcoin. Risk management is a discipline that can be used to address the possibility of future threats which may cause harm to the existing systems. Although there has been considerable work on analysing Bitcoin in terms of the potential issues it brings to the economic landscape, this report performs a first ever attempt of identifying the threats and risks posed by the use of Bitcoin from the perspective of computational modeling and engineering. In this project we consider risk at all levels of interaction when Bitcoin is introduced and transferred across the systems. We look at the infrastructure and the computational working of the digital currency to identify the potential risks it brings. Additional information can be seen in our forthcoming companion report on the detailed modeling of Bitcoin.

No description available.

No

Peer-to-Peer-Finanzierungen haben in den letzten Jahren nicht nur aufgrund ihres disruptiven Charakters, sondern auch aufgrund ihres raschen Wachstums und der wachsenden Bandbreite an Dienstleistungen zunehmend Beachtung gefunden. Peer-to-Peer Kreditplattformen versuchen, Banken zu umgehen, um Kreditnehmern eine Alternative und Anlegern eine neue Anlageklasse anzubieten - wird dies zu einem „Banking ohne Banken“ führen? Peer-to-Peer Betreiber müssen darauf achten, dass sie ihre Geschäfte gemäß den geltenden Gesetzen und Vorschriften planen und betreiben, auch wenn sie mit einer Bank zusammenarbeiten, die als Kreditgeber fungiert, da die Nichteinhaltung der geltenden Vorschriften unter anderem zivil- und strafrechtliche Sanktionen, Prozesskosten sowie nachteilige Publizität und im schlimmsten Fall die Beendigung des Geschäfts nach sich ziehen kann. Zusätzliche Schwierigkeiten ergeben sich aufgrund unterschiedlicher Vorschriften in den europäischen Ländern. Infolgedessen muss eine neue Beurteilung des rechtlichen Umfelds vorgenommen werden, bevor ein Peer-to-Peer Betreiber sein Geschäft auf andere Länder ausweiten kann, was häufig zu unterschiedlichen Konfigurationen und Geschäftsmodellen führt. In dieser Dissertation sollen die wichtigsten Bestimmungen für die Vergabe von Peer-to-Peer Krediten herausgearbeitet werden. Der Schwerpunkt liegt auf den rechtlichen Rahmenbedingungen für Peer-to-Peer Kredite in Deutschland, d.h. welche Vorschriften diese Plattformen erfüllen müssen, um ihr Geschäftsmodell zu betreiben, und/ oder welche Vorschriften und Lizenzanforderungen für diese Unternehmen gelten. Zunächst wird erklärt, was Peer-to-Peer Kredite sind, wie sie sich entwickelt haben und wie sie funktionieren. Die rechtlichen Rahmenbedingungen werden sowohl für Deutschland als auch für europäische Länder, nämlich das Vereinigte Königreich, Schweden und die Niederlande, im Vergleich untersucht. Anschließend wird untersucht, warum verschiedene europäische Länder unterschiedliche Regeln anwenden und ob es möglich wäre, solche Regelungen für Peer-to-Peer Kredite in ganz Europa zu harmonisieren und gleichzeitig sicherzustellen, dass die Hauptgründe der Länder erfüllt werden. / Peer-to-peer finance has received increasing attention over the last years, not only because of its disruptive nature, but also because of its rapid growth and expanding breadth of services. Peer-to-peer lending platforms try to circumvent banks to offer borrowers an alternative and investors a new asset class – will this lead to a “Banking without banks”. Peer-to-peer operators need to be careful to plan and operate their business in compliance with applicable laws and regulations, even if they cooperate with a non-affiliated bank that acts as lender of record, since failure to comply with applicable regulations can result in, among others, civil and criminal penalties, litigation expenses as well as adverse publicity and in the worst case the termination of the business. Additional difficulties arise due to different regulations across European countries. Consequently a new assessment of the legal environment needs to be made before a peer-to-peer operator can expand its business into other countries and often leads to differing setups and business models. The dissertation is intended to identify principal regulations that apply to peer-to-peer lending. The focus lies on the legal framework for peer-to-peer lending in Germany, i.e. which regulations such platforms have to comply with in order to operate their business model and/or which regulations are applicable to such businesses and which license requirements apply. First of all it will be explained what peer-to-peer lending is, how it evolved and how it works. The legal framework will be investigated with regards to Germany as well as European countries, namely the United Kingdom, Sweden and the Netherlands, in comparison. It will then be examined why different European countries apply different rules and whether it would be possible to harmonise such regulations for peer-to-peer lending across Europe whilst ensuring that the countries’ main rationales are fulfilled.

Die Erfindung von Bitcoin hat ein großes Interesse an dezentralen Systemen geweckt. Eine häufige Zuschreibung an dezentrale Systeme ist dabei, dass eine Dezentralisierung automatisch zu einer höheren Sicherheit und Widerstandsfähigkeit gegenüber Angriffen führt. Diese Dissertation widmet sich dieser Zuschreibung, indem untersucht wird, ob dezentralisierte Anwendungen tatsächlich so robust sind. Dafür werden exemplarisch drei Systeme untersucht, die häufig als Komponenten in komplexen Blockchain-Anwendungen benutzt werden: Ethereum als Infrastruktur, IPFS zur verteilten Datenspeicherung und schließlich "Stablecoins" als Tokens mit Wertstabilität. Die Sicherheit und Robustheit dieser einzelnen Komponenten bestimmt maßgeblich die Sicherheit des Gesamtsystems in dem sie verwendet werden; darüber hinaus erlaubt der Fokus auf Komponenten Schlussfolgerungen über individuelle Anwendungen hinaus. Für die entsprechende Analyse bedient sich diese Arbeit einer empirisch motivierten, meist Netzwerklayer-basierten Perspektive -- angereichert mit einer ökonomischen im Kontext von Wertstabilen Tokens. Dieses empirische Verständnis ermöglicht es Aussagen über die inhärenten Eigenschaften der studierten Systeme zu treffen. Ein zentrales Ergebnis dieser Arbeit ist die Entdeckung und Demonstration einer "Eclipse-Attack" auf das Ethereum Overlay. Mittels eines solchen Angriffs kann ein Angreifer die Verbreitung von Transaktionen und Blöcken behindern und Netzwerkteilnehmer aus dem Overlay ausschließen. Des weiteren wird das IPFS-Netzwerk umfassend analysiert und kartografiert mithilfe (1) systematischer Crawls der DHT sowie (2) des Mitschneidens von Anfragenachrichten für Daten. Erkenntlich wird hierbei, dass die hybride Overlay-Struktur von IPFS Segen und Fluch zugleich ist, da das Gesamtsystem zwar robust gegen Angriffe ist, gleichzeitig aber eine umfassende Überwachung der Netzwerkteilnehmer ermöglicht wird. Im Rahmen der wertstabilen Kryptowährungen wird ein Klassifikations-Framework vorgestellt und auf aktuelle Entwicklungen im Gebiet der "Stablecoins" angewandt. Mit diesem Framework wird somit (1) der aktuelle Zustand der Stablecoin-Landschaft sortiert und (2) ein Mittel zur Verfügung gestellt, um auch zukünftige Designs einzuordnen und zu verstehen. / The inception of Bitcoin has sparked a large interest in decentralized systems. In particular, popular narratives imply that decentralization automatically leads to a high security and resilience against attacks, even against powerful adversaries. In this thesis, we investigate whether these ascriptions are appropriate and if decentralized applications are as robust as they are made out to be. To this end, we exemplarily analyze three widely-used systems that function as building blocks for blockchain applications: Ethereum as basic infrastructure, IPFS for distributed storage and lastly "stablecoins" as tokens with a stable value. As reoccurring building blocks for decentralized applications these examples significantly determine the security and resilience of the overall application. Furthermore, focusing on these building blocks allows us to look past individual applications and focus on inherent systemic properties. The analysis is driven by a strong empirical, mostly network-layer based perspective; enriched with an economic point of view in the context of monetary stabilization. The resulting practical understanding allows us to delve into the systems' inherent properties. The fundamental results of this thesis include the demonstration of a network-layer Eclipse attack on the Ethereum overlay which can be leveraged to impede the delivery of transaction and blocks with dire consequences for applications built on top of Ethereum. Furthermore, we extensively map the IPFS network through (1) systematic crawling of its DHT, as well as (2) monitoring content requests. We show that while IPFS' hybrid overlay structure renders it quite robust against attacks, this virtue of the overlay is simultaneously a curse, as it allows for extensive monitoring of participating peers and the data they request. Lastly, we exchange the network-layer perspective for a mostly economic one in the context of monetary stabilization. We present a classification framework to (1) map out the stablecoin landscape and (2) provide means to pigeon-hole future system designs. With our work we not only scrutinize ascriptions attributed to decentral technologies; we also reached out to IPFS and Ethereum developers to discuss results and remedy potential attack vectors.

Legal issues of the Internet from the scope of international and national law Global internet network has changed the social, political and business life of most people in the World. Communication is much faster, the flow of information all around the World takes a few seconds. Exchange of political opinions, personal and business information, works protected by copyright and other information has become unstoppable. Members of the international community are trying to tackle this new challenge to their legal and political systems. This diploma thesis is describing some arreas of private law where Internet plays the most important role and has changed the scope and interpretation of many legal rules. The work is dividend into two main parts. The first one deals with general aspects of the Internet such as its history, architecture, different regulatory layers, the copyright law on-line, general legal issues arising from the Yahoo! case and its impact on political systems. The second part describes more specific areas mainly focused on the protection of personality and personal data in the on-line environment. To be more specific, there are chapters dealing with communication software, social networks, direct business and usage of the Internet for business reasons. Specific chapter is dedicated to...

Com o advento da internet, surgem no campo da filantropia plataformas digitais que utilizam o poder de mobilização de indivíduos da web 2.0 para apoiar financeiramente projetos socioambientais. Esta dissertação tem por base as experiências da startup Eventos do Bem, que utiliza o método de angariação online Peer-to- Peer (P2P). A abordagem digital do método de captação de recursos P2P consiste na elaboração de campanhas promovidas por indivíduos online os quais podem utilizar seus eventos pessoais prol de uma causa social - como aniversários, casamentos entre outros - para mobilizar sua rede de contatos propondo que seus conhecidos doem para sua campanha ao invés de os presentearem no aniversário. As experiências na realização de campanhas digitais em prol de organizações sociais no referido empreendimento, elucubraram problemas relativos à performance financeira das campanhas. Logo, esta pesquisa foi realizada com o objetivo de propor diretrizes e práticas que potencializem o sucesso deste tipo de arrecadação online. Visto ser um modelo aplicado de forma pioneira no país, como metodologia, optou-se pela estratégia de estudos de caso múltiplos com base em YIN (1994) na qual, em conjunto com o estudo da startup Eventos do Bem, selecionou-se a plataforma estadunidense Charity:Water, referência em angariação P2P. Como unidades de análise, foram abordadas as campanhas de angariação realizadas em ambas as plataformas, focando na categoria de campanhas de aniversário. Logo, o trajeto desta pesquisa delineou-se nas fases: (a) análise da experiência da startup Eventos do Bem, em paralelo com a leitura do referencial teórico pertinente; (b) pesquisa e seleção da plataforma Charity:Water; (c) estudo e realização de 46 entrevistas, compondo-se em 6 entrevistas com funcionários do Charity:Water e 40 efetivadas com criadores de campanhas de aniversário em ambas as plataformas; (d) análise de fatores e práticas influenciadoras das campanhas promovidas nos casos abordados; (e) estudo cross- case e análise dos resultados obtidos. Como resultado da pesquisa, foi delineado um procedimento de boas práticas para potencializar a performance das campanhas digitais, destacando-se ações referentes à interação individual do criador da campanha com toda a sua rede de contatos, a persistência no pedido e a realização de um discurso do pedido de doação com qualidade, isto é, que apresente argumentos para persuadir doadores mais emocionais como também os mais racionais e lógicos. Desta forma, o estudo contribuiu para expandir o debate de captação de recursos online e aponta inovações da técnica P2P no que tange à mecânica do processo de decisão para doar e demonstra que a técnica pode fornecer resultados que vão além da angariação de recursos, estimulando maior engajamento social dos participantes. / With the advent of the Internet, philanthropy is emerging in digital platforms that use the mobilization power of web 2.0 individuals to financially support social and environmental projects. This dissertation is based on the experiences of the startup Eventos do Bem, which uses the Peer-to-Peer (P2P) online raising method. The digital approach of the P2P method of fundraising consists of the elaboration of campaigns promoted by individuals online who can use their personal events for a social cause - such as anniversaries, weddings and others - to mobilize their network of contacts by proposing that their acquaintances ache for their campaign instead of giving them on their birthday. The experiences in the accomplishment of digital campaigns in favor of social organizations in the mentioned enterprise, they have presented problems related to the financial performance of the campaigns. Therefore, this research was carried out with the objective of proposing guidelines and practices that will enhance the success of this type of online collection. As a model pioneered in the country, as a methodology, we chose the strategy of multiple case studies based on YIN (1994) in which, together with the study of the startup Eventos do Bem, we selected the platform American Charity: Water, reference in P2P fundraising. As units of analysis, the campaigns of raising were carried out in both platforms, focusing on the category of birthday campaigns.Therefore, the study\'s path was delineated in the phases: (a) analysis of the startup experience of the Good Events, in parallel with the reading of the relevant theoretical reference; (B) research and selection of the Charity: Water platform; (C) study and performance of 46 interviews, comprising 6 interviews with Charity: Water employees and 40 interviews with fundraisers on both platforms; (D) analysis of factors and practices influencing the campaigns promoted in the cases addressed; (E) cross-case study and analysis of the results obtained. As a result, a procedure of good practices was designed to potentiate fundraising P2P performance, highlighting actions regarding the individual interaction of the campaigner with his entire network of contacts, a persistence without request and realization of a speech of the Request Of giving with quality, is, and presents arguments to persuade donors more emotional as also the most rational and logical. In this way, the study contributed to expand the online fundraising debate and points out innovations of the P2P technique regarding the mechanics of the decision process to donate and demonstrates that the technique can provide results that go beyond fundraising, Stimulating greater social engagement of participants.