Comparison of proof-of-work based blockchains against federated consensus and proof-of-validation based blockchains

This paper reports the results of survey done on the architecture and functionalities involved in blockchains. Moreover, it reports the results of comparison between proof-of-work-based blockchains, Bitcoin and Ethereum, against federated consensus-based blockchain, Ripple, and proof-of-validation-based blockchain, Tendermint, along the parameters like peer to peer network setup and maintenance, cryptocurrency involved, details of transaction execution and validation, block creation, block validation and consensus protocol and application development

The Cloud Strikes Back: Investigating the Decentralization of IPFS

Interplanetary Filesystem (IPFS) is one of the largest peer-to-peer filesystems in operation. The network is the default storage layer for Web3 and is being presented as a solution to the centralization of the web. In this paper, we present a large-scale, multi-modal measurement study of the IPFS network. We analyze the topology, the traffic, the content providers and the entry points from the classical Internet. Our measurements show significant centralization in the IPFS network and a high share of nodes hosted in the cloud. We also shed light on the main stakeholders in the ecosystem. We discuss key challenges that might disrupt continuing efforts to decentralize the Web and highlight multiple properties that are creating pressures toward centralization

The Worm: Design, Structure and Functionality

Tato diplomová práce se zabývá problematikou počítačové bezpečnosti, především v oblastech malwaru známého jako počítačový červ. Cílem je sestrojit aktuální příručku zabývající se tímto typem malwaru, především jeho strukturou a funkcionalitou. Práce také nabízí nové metody rozdělení červů a jejich šíření. V praktické části je realizován multivektorový červ pro systémy Windows, napsaný v programovacím jazyce C#. Tento červ je schopný šíření po sdílených složkách, emailové komunikaci a SSH a obsahuje nedestruktivní i destruktivní aktivační rutinu, se systémem dovolující vzdálené stahování a spouštění souborů.This diploma thesis deals with problematics of computer security, primarily in the area of malware known as computer worm. The main aim of this thesis is to build an up-to-date handbook, dealing with this type of malware, especially its structure and functionality. The thesis also offers a new method of splitting worms and spreading. In practical part is implemented multivector worm for system Windows written in C#. This worm is capable of spreading over shared folders, email communications, and SSH. Also, the worm contains both nondestructive and destructive payload with the system allowing remote download and execution of files.460 - Katedra informatikyvelmi dobř

Approximate information filtering in structured peer-to-peer networks

Today';s content providers are naturally distributed and produce large amounts of information every day, making peer-to-peer data management a promising approach offering scalability, adaptivity to dynamics, and failure resilience. In such systems, subscribing with a continuous query is of equal importance as one-time querying since it allows the user to cope with the high rate of information production and avoid the cognitive overload of repeated searches. In the information filtering setting users specify continuous queries, thus subscribing to newly appearing documents satisfying the query conditions. Contrary to existing approaches providing exact information filtering functionality, this doctoral thesis introduces the concept of approximate information filtering, where users subscribe to only a few selected sources most likely to satisfy their information demand. This way, efficiency and scalability are enhanced by trading a small reduction in recall for lower message traffic. This thesis contains the following contributions: (i) the first architecture to support approximate information filtering in structured peer-to-peer networks, (ii) novel strategies to select the most appropriate publishers by taking into account correlations among keywords, (iii) a prototype implementation for approximate information retrieval and filtering, and (iv) a digital library use case to demonstrate the integration of retrieval and filtering in a unified system.Heutige Content-Anbieter sind verteilt und produzieren riesige Mengen an Daten jeden Tag. Daher wird die Datenhaltung in Peer-to-Peer Netzen zu einem vielversprechenden Ansatz, der Skalierbarkeit, Anpassbarkeit an Dynamik und Ausfallsicherheit bietet. Für solche Systeme besitzt das Abonnieren mit Daueranfragen die gleiche Wichtigkeit wie einmalige Anfragen, da dies dem Nutzer erlaubt, mit der hohen Datenrate umzugehen und gleichzeitig die Überlastung durch erneutes Suchen verhindert. Im Information Filtering Szenario legen Nutzer Daueranfragen fest und abonnieren dadurch neue Dokumente, die die Anfrage erfüllen. Im Gegensatz zu vorhandenen Ansätzen für exaktes Information Filtering führt diese Doktorarbeit das Konzept von approximativem Information Filtering ein. Ein Nutzer abonniert nur wenige ausgewählte Quellen, die am ehesten die Anfrage erfüllen werden. Effizienz und Skalierbarkeit werden verbessert, indem Recall gegen einen geringeren Nachrichtenverkehr eingetauscht wird. Diese Arbeit beinhaltet folgende Beiträge: (i) die erste Architektur für approximatives Information Filtering in strukturierten Peer-to-Peer Netzen, (ii) Strategien zur Wahl der besten Anbieter unter Berücksichtigung von Schlüsselwörter-Korrelationen, (iii) ein Prototyp, der approximatives Information Retrieval und Filtering realisiert und (iv) ein Anwendungsfall für Digitale Bibliotheken, der beide Funktionalitäten in einem vereinten System aufzeigt

Controlling P2P File-Sharing Networks Traffic

Since the appearance of Peer-To-Peer (P2P) file-sharing networks some time ago, many Internet users have chosen this technology to share and search programs, videos, music, documents, etc. The total number of P2P file-sharing users has been increasing and decreasing in the last decade depending on the creation or end of some well known P2P file-sharing systems. P2P file-sharing networks traffic is currently overloading some data networks and it is a major headache for network administrators because it is difficult to control this kind of traffic (mainly because some P2P file-sharing networks encrypt their messages). This paper deals with the analysis, taxonomy and characterization of eight Public P2P file-sharing networks: Gnutella, Freeenet, Soulseek, BitTorrent, Opennap, eDonkey, MP2P and FastTrack. These eight most popular networks have been selected due to their different type of working architecture. Then, we will show the amount of users, files and the size of files inside these file-sharing networks. Finally, several network configurations are presented in order to control P2P file-sharing traffic in the network.García Pineda, M.; Hammoumi, M.; Canovas Solbes, A.; Lloret, J. (2011). Controlling P2P File-Sharing Networks Traffic. Network Protocols and Algorithms. 3(4):54-92. doi:10.5296/npa.v3i4.1365S54923

Contributions to High-Throughput Computing Based on the Peer-to-Peer Paradigm

XII, 116 p.This dissertation focuses on High Throughput Computing (HTC) systems and how to build a working HTC system using Peer-to-Peer (P2P) technologies. The traditional HTC systems, designed to process the largest possible number of tasks per unit of time, revolve around a central node that implements a queue used to store and manage submitted tasks. This central node limits the scalability and fault tolerance of the HTC system. A usual solution involves the utilization of replicas of the master node that can replace it. This solution is, however, limited by the number of replicas used. In this thesis, we propose an alternative solution that follows the P2P philosophy: a completely distributed system in which all worker nodes participate in the scheduling tasks, and with a physically distributed task queue implemented on top of a P2P storage system. The fault tolerance and scalability of this proposal is, therefore, limited only by the number of nodes in the system. The proper operation and scalability of our proposal have been validated through experimentation with a real system. The data availability provided by Cassandra, the P2P data management framework used in our proposal, is analysed by means of several stochastic models. These models can be used to make predictions about the availability of any Cassandra deployment, as well as to select the best possible con guration of any Cassandra system. In order to validate the proposed models, an experimentation with real Cassandra clusters is made, showing that our models are good descriptors of Cassandra's availability. Finally, we propose a set of scheduling policies that try to solve a common problem of HTC systems: re-execution of tasks due to a failure in the node where the task was running, without additional resource misspending. In order to reduce the number of re-executions, our proposals try to nd good ts between the reliability of nodes and the estimated length of each task. An extensive simulation-based experimentation shows that our policies are capable of reducing the number of re-executions, improving system performance and utilization of nodes

An architectural framework for self-configuration and self-improvement at runtime

[no abstract

Music and Digital Media

Anthropology has neglected the study of music. Music and Digital Media shows how and why this should be redressed. It does so by enabling music to expand the horizons of digital anthropology, demonstrating how the field can build interdisciplinary links to music and sound studies, digital/media studies, and science and technology studies. Music and Digital Media is the first comparative ethnographic study of the impact of digital media on music worldwide. It offers a radical and lucid new theoretical framework for understanding digital media through music, showing that music is today where the promises and problems of the digital assume clamouring audibility. The book contains ten chapters, eight of which present comprehensive original ethnographies; they are bookended by an authoritative introduction and a comparative postlude. Five chapters address popular, folk, art and crossover musics in the global South and North, including Kenya, Argentina, India, Canada and the UK. Three chapters bring the digital experimentally to the fore, presenting pioneering ethnographies of anextra-legal peer-to-peer site and the streaming platform Spotify, a series of prominent internet-mediated music genres, and the first ethnography of a global software package, the interactive music platform Max. The book is unique in bringing ethnographic research on popular, folk, art and crossover musics from the global North and South into a comparative framework on a large scale, and creates an innovative new paradigm for comparative anthropology. It shows how music enlarges anthropology while demanding to be understood with reference to classic themes of anthropological theory. Praise for Music and Digital Media ‘Music and Digital Media is a groundbreaking update to our understandings of sound, media, digitization, and music. Truly transdisciplinary and transnational in scope, it innovates methodologically through new models for collaboration, multi-sited ethnography, and comparative work. It also offers an important defense of—and advancement of—theories of mediation.’ Jonathan Sterne, Communication Studies and Art History, McGill University 'Music and Digital Media is a nuanced exploration of the burgeoning digital music scene across both the global North and the global South. Ethnographically rich and theoretically sophisticated, this collection will become the new standard for this field.' Anna Tsing, Anthropology, University of California at Santa Cruz 'The global drama of music's digitisation elicits extreme responses – from catastrophe to piratical opportunism – but between them lie more nuanced perspectives. This timely, absolutely necessary collection applies anthropological understanding to a deliriously immersive field, bringing welcome clarity to complex processes whose impact is felt far beyond what we call music.' David Toop, London College of Communication, musician and writer ‘Spanning continents and academic disciplines, the rich ethnographies contained in Music and Digital Media makes it obligatory reading for anyone wishing to understand the complex, contradictory, and momentous effects that digitization is having on musical cultures.’ Eric Drott, Music, University of Texas, Austin ‘This superb collection, with an authoritative overview as its introduction, represents the state of the art in studies of the digitalisation of music. It is also a testament to what anthropology at its reflexive best can offer the rest of the social sciences and humanities.’ David Hesmondhalgh, Media and Communication, University of Leeds ‘This exciting volume forges new ground in the study of local conditions, institutions, and sounds of digital music in the Global South and North. The book’s planetary scope and its commitment to the “messiness” of ethnographic sites and concepts amplifies emergent configurations and meanings of music, the digital, and the aesthetic.’ Marina Peterson, Anthropology, University of Texas, Austi

Music and Digital Media: A planetary anthropology

Anthropology has neglected the study of music. Music and Digital Media shows how and why this should be redressed. It does so by enabling music to expand the horizons of digital anthropology, demonstrating how the field can build interdisciplinary links to music and sound studies, digital/media studies, and science and technology studies. Music and Digital Media is the first comparative ethnographic study of the impact of digital media on music worldwide. It offers a radical and lucid new theoretical framework for understanding digital media through music, showing that music is today where the promises and problems of the digital assume clamouring audibility. The book contains ten chapters, eight of which present comprehensive original ethnographies; they are bookended by an authoritative introduction and a comparative postlude. Five chapters address popular, folk, art and crossover musics in the global South and North, including Kenya, Argentina, India, Canada and the UK. Three chapters bring the digital experimentally to the fore, presenting pioneering ethnographies of an extra-legal peer-to-peer site and the streaming platform Spotify, a series of prominent internet-mediated music genres, and the first ethnography of a global software package, the interactive music platform Max. The book is unique in bringing ethnographic research on popular, folk, art and crossover musics from the global North and South into a comparative framework on a large scale, and creates an innovative new paradigm for comparative anthropology. It shows how music enlarges anthropology while demanding to be understood with reference to classic themes of anthropological theory

Music and Digital Media

Anthropology has neglected the study of music. Music and Digital Media shows how and why this should be redressed. It does so by enabling music to expand the horizons of digital anthropology, demonstrating how the field can build interdisciplinary links to music and sound studies, digital/media studies, and science and technology studies. Music and Digital Media is the first comparative ethnographic study of the impact of digital media on music worldwide. It offers a radical and lucid new theoretical framework for understanding digital media through music, showing that music is today where the promises and problems of the digital assume clamouring audibility. The book contains ten chapters, eight of which present comprehensive original ethnographies; they are bookended by an authoritative introduction and a comparative postlude. Five chapters address popular, folk, art and crossover musics in the global South and North, including Kenya, Argentina, India, Canada and the UK. Three chapters bring the digital experimentally to the fore, presenting pioneering ethnographies of anextra-legal peer-to-peer site and the streaming platform Spotify, a series of prominent internet-mediated music genres, and the first ethnography of a global software package, the interactive music platform Max. The book is unique in bringing ethnographic research on popular, folk, art and crossover musics from the global North and South into a comparative framework on a large scale, and creates an innovative new paradigm for comparative anthropology. It shows how music enlarges anthropology while demanding to be understood with reference to classic themes of anthropological theory. Praise for Music and Digital Media ‘Music and Digital Media is a groundbreaking update to our understandings of sound, media, digitization, and music. Truly transdisciplinary and transnational in scope, it innovates methodologically through new models for collaboration, multi-sited ethnography, and comparative work. It also offers an important defense of—and advancement of—theories of mediation.’ Jonathan Sterne, Communication Studies and Art History, McGill University 'Music and Digital Media is a nuanced exploration of the burgeoning digital music scene across both the global North and the global South. Ethnographically rich and theoretically sophisticated, this collection will become the new standard for this field.' Anna Tsing, Anthropology, University of California at Santa Cruz 'The global drama of music's digitisation elicits extreme responses – from catastrophe to piratical opportunism – but between them lie more nuanced perspectives. This timely, absolutely necessary collection applies anthropological understanding to a deliriously immersive field, bringing welcome clarity to complex processes whose impact is felt far beyond what we call music.' David Toop, London College of Communication, musician and writer ‘Spanning continents and academic disciplines, the rich ethnographies contained in Music and Digital Media makes it obligatory reading for anyone wishing to understand the complex, contradictory, and momentous effects that digitization is having on musical cultures.’ Eric Drott, Music, University of Texas, Austin ‘This superb collection, with an authoritative overview as its introduction, represents the state of the art in studies of the digitalisation of music. It is also a testament to what anthropology at its reflexive best can offer the rest of the social sciences and humanities.’ David Hesmondhalgh, Media and Communication, University of Leeds ‘This exciting volume forges new ground in the study of local conditions, institutions, and sounds of digital music in the Global South and North. The book’s planetary scope and its commitment to the “messiness” of ethnographic sites and concepts amplifies emergent configurations and meanings of music, the digital, and the aesthetic.’ Marina Peterson, Anthropology, University of Texas, Austi