Peer to Peer Networks

Most current P2P file sharing systems treat their users as anonymous, unrelated entities, and completely disregard any social relationships between them. However, social phenomena such as friendship and the existence of communities of users with similar tastes may be well exploited in such systems, to increase their usability and performance. In this paper we present a novel social-based P2P file-sharing paradigm that exploits social phenomena by maintaining social networks and using these in content discovery, content recommendation, and downloading. Based on this paradigm's first class concepts such as taste groups, friends, and friends-offriends, we have designed and implemented the TRIBLER P2P filesharing system as a set of extensions to Bittorrent. We present and discuss the design of TRIBLER, and we show evidence that TRIBLER enables fast, trusted content discovery and recommendation at a low additional overhead, and a significant improvement in download performance.

Collaborative filtering requires a centralized rating database. However, within a peer-to-peer network such a centralized database is not readily available. In this paper, we propose a fully distributed collaborative filtering method that is self-organizing and operates in a distributed way. Similarity ranks between multimedia files (items) are calculated by log-based user profiles and are stored locally at these items in so-called buddy tables. This intuitively creates a semantic overlay to organize multimedia files. Based on this semantic overlay and the items that a user has downloaded previously (indicating the profile of the user), recommendations can be performed and the recommended items can be easily located. We have tested our distributed collaborative filtering approach and compared it to centralized collaborative filtering, showing that it has similar performance. It is therefore a promising technique to facilitate filtering for relevant multimedia data in P2P networks.

Most current P2P file sharing systems treat their users as anonymous, unrelated entities, and completely disregard any social relationships between them. However, social phenomena such as friendship and the existence of communities of users with similar tastes may be well exploited in such systems, to increase their usability and performance. In this paper we present a novel social-based P2P file-sharing paradigm that exploits social phenomena by maintaining social networks and using these in content discovery, content recommendation, and downloading. Based on this paradigm's first class concepts such as taste groups, friends, and friends-offriends, we have designed and implemented the TRIBLER P2P filesharing system as a set of extensions to Bittorrent. We present and discuss the design of TRIBLER, and we show evidence that TRIBLER enables fast, trusted content discovery and recommendation at a low additional overhead, and a significant improvement in download performance.

The existing peer-to-peer networks have several problems such as fake content distribution, free riding, white-washing and poor search scalability, lack of a robust trust model and absence of user privacy protection mechanism. Although, several trust management and semantic community-based mechanisms for combating free riding and distribution of malicious contents have been proposed by some researchers, most of these schemes lack scalability due to their high computational, communication and storage overhead. This paper presents a robust trust management scheme for P2P networks that utilizes topology adaptation by constructing an overlay of trusted peers where the neighbors are selected based on their trust ratings and content similarities. While increasing the search efficiency by intelligently exploiting the formation of semantic community structures by topology adaptation among the trustworthy peers, the scheme provides the users a very high level of privacy protection of their usage and consumption patterns of network resources. Simulation results demonstrate that the proposed scheme provides efficient searching to good peers while penalizing the malicious peers by increasing their search times as the network topology stabilizes.

In presenting this project in partial fulfillment of the requirements for a postgraduate degree from the Universiti Utara Malaysia, I agree that the University Library may make it freely available for inspection. I further agree that permission for copying of this project in any manner in whole or in part, for scholarly purposes may be granted by my supervisor(s) or in their absence by the Dean of Awang Had Salleh Graduate School. It is understood that any copying or publication or use of this project or parts for financial gain shall not be allowed without my written permission. It is also understood that due recognition shall be given to me and to Universiti Utara Malaysia for any scholarly use which may be made of any material from my project.

Online health communities (OHCs) have become new venues for online professional-patient interactions in which patients, as OHC users, can undertake online consultations with health professional moderators. This interaction has previously been investigated mainly from the user's perspective, whilst neglecting the insights of health professional moderators. The aim of this study is to explore and compare the benefits and challenges of online professional-patient interactions for users and health professional moderators and the effects on face-to-face medical encounters. The study employed a qualitative research design, with in-depth, semi-structured interviews conducted with users (n ¼ 8) and health professional moderators (n ¼ 7) from the largest OHC in Slovenia. Data analysis utilised inductive thematic analysis and principles of grounded theory. The results of this small study demonstrate that the OHC enabled users and health professional moderators to overcome weaknesses of face-to-face medical encounters. Both users and professionals view the primary benefits of online professional-patient interaction as delivering informational and emotional support for users' health-related needs. The main challenges for users and health professional moderators stem from the limitations of computermediated communication (CMC). Users and health professional moderators expressed different and ambivalent attitudes toward the OHC and its effect on face-to-face medical encounters.

Several protocol efficiency metrics (e.g., scalability, search success rate, routing reachability and stability) depend on the capability of preserving structure even over the churn caused by the ad-hoc nodes joining or leaving the network. Preserving the structure becomes more prohibitive due to the distributed and potentially uncooperative nature of such networks, as in the peer-to-peer (P2P) networks. Thus, most practical solutions involve unstructured approaches while attempting to maintain the structure at various levels of protocol stack. The primary focus of this paper is to investigate construction and maintenance of scale-free topologies in a distributed manner without requiring global topology information at the time when nodes join or leave. We consider the uncooperative behavior of peers by limiting the number of neighbors to a predefined hard cutoff value (i.e., no peer is a major hub), and the ad-hoc behavior of peers by rewiring the neighbors of nodes leaving the network. We also investigate the effect of these hard cutoffs and rewiring of ad-hoc nodes on the P2P search efficiency.

The greatest problem for e-Supply Chain Management (e-SCM) is the cost of delivery. In the situation of returned products, transportation has to be paid twice. Reverse logistics is the process of transferring products from their typical final place to its origin for the purpose of capturing value or defect on the product. Additionally to this there are also costs of correction of invoices, inspection of products and refund. One method to solve this problem is demand forecasting which depends on its coordination and integration of the supply chain. However, this type of solution requires extra effort to forecast expected future demand. Recently, blockchain is emerged as a novel approach to building trust in a trustless environment and thereby guarantees data integrity, availability, traceability and security in data management and it presents a valuable solution to e-SCM. This research illustrates how to solve the problem of reverse logistics in e-SCM using blockchain technology to e...

STESH proposes a peer-to-peer network connecting India’s 5M coders with idle GPUs (~80% idle, Industry Report, 2024) for AI compute at ~₹62-₹83/hour. Targeting ~₹83Cr (1%) of India’s ~₹8,300Cr AI market by 2032 (NASSCOM, 2024), STESH uses blockchain (~₹0.8/tx), zero-knowledge proofs (~10-30s), and UPI (~83% penetration, RBI, 2024) for secure, affordable access. Our Proof-of-Compute ensures verifiable GPU usage, addressing coders’ budget constraints (~₹8,000/month). Supported by ~15 early testers, STESH aims for a Q2 2025 beta, integrating ~10,000 GPUs. This white paper outlines the technical framework, market analysis, and beta roadmap, seeking feedback from AI/blockchain researchers to refine our decentralised platform for India’s AI ecosystem.

Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html.

Ubiquitous information technologies like RFID allow for immediate, extensive and fine-grained capture of real world information. Scalable and efficient networks for exchange of this vast amount of information amongst companies are crucial for the economic exploitation of benefits of ubiquitous information technologies. Existing networks bear several limitations like risks of single-point-offailures or bottlenecks, unequally distributed power and burdens as well as inflexibility through stringent structures and formats. In particular there is a need for improving the scalability of solutions and ensuring autonomy of network participants. In this paper we introduce a Peer-to-Peer-based architecture for exchanging distributed information, which are shared among participants of a supply chain facilitated with ubiquitous information technologies. This architecture builds on the wellestablished EPCglobal standards, but can be implemented as an autonomous network. Unlike other architectures it does not need central coordination mechanisms, because it is based on self-organizing Peer-to-Peer protocols. We argue that our architecture supports business processes especially of small and medium-sized enterprises better than other architectures. We provide a discussion about requirements for solutions and a simulation-based analysis of the proposed architecture.

In today's digital age, technological advancements are driving the transformation of urban areas into smart cities by incorporating innovative solutions across multiple sectors. Blockchain technology, known for its decentralized and secure framework, holds great potential for improving both security and efficiency in smart city infrastructure. This study examines the integration of blockchain within key smart city components, with a particular focus on governance and healthcare. A decentralized blockchain-based voting system is introduced as a reliable alternative to conventional voting methods, ensuring transparency and reducing reliance on third-party involvement. Furthermore, a blockchain-powered medical record system is designed to strengthen data security and prevent unauthorized modifications. Despite its numerous benefits, the study recognizes the difficulties in implementing blockchain across all aspects of a smart city due to the interconnected nature of various applications. To address this, a model is developed to assess decentralized applications utilizing blockchain technology. The results highlight blockchain's significant role in enhanc-Blockchain Based Decentralized Smart City Components Analysis

There has been significant interest recently in designing reputation systems to address the problem of file authenticity in P2P networks. However, many of the systems proposed make different assumptions, and cannot easily be compared. The development of a model to evaluate such systems is imperative to quantitatively study such reputation systems. In this paper, we outline several major research issues in developing a model and metrics to evaluate reputation systems for file authenticity.

Assessing the performance of peer-to-peer algorithms is impossible without simulations since testing new algorithms by deploying them in an existing P2P network is prohibitively expensive. However, some P2P algorithms are sensitive to the network and traffic models that are used in the simulations. In order to produce realistic results, we therefore require simulations that resemble real-world P2P networks as closely as possible. We describe the Query-Cycle Simulator, a simulator for file-sharing P2P networks networks. We link the Query-Cycle Simulator to measurements on existing P2P networks and discuss some open issues in simulating these networks.

Peer-to-peer file-sharing networks are currently receiving much attention as a means of sharing and distributing information. However, as recent experience with P2P networks such as Gnutella shows, the anonymous, open nature of these networks offers an almost ideal environment for the spread of self-replicating inauthentic files. We describe an algorithm to decrease the number of downloads of inauthentic files in a peer-to-peer file-sharing network that assigns each peer a unique global reputation value, based on the peer's history of uploads. We present a distributed and secure method to compute global reputation values, based on Power iteration. By having peers use these global reputation values to choose the peers from whom they download, the network effectively identifies malicious peers and isolates them from the network. In simulations, this reputation system has been shown to significantly decrease the number of inauthentic files on the network, even under a variety of conditions where malicious peers cooperate in an attempt to deliberately subvert the system.

À minha família, em especial ao meu pai José e minha tia Fabiola, que sempre me apoiaram e incentivaram. Aos meus amigos Acácio, Gustavo e Carlinhos, colegas de trabalho e moradia, que vivenciaram os desaos diários comigo. Ao Professor Marcio, meu orientador, pela paciência, conança e ensinamentos transmitidos. Aos meus amigos Pedro, Fabrizio, Samihr, Ygor e Efraim pelos momentos de diversão e descontração memoráveis. Aos amigos da sala experimental, companheiros na luta diária. Aos professores Felipe e Edimilson, que sempre me atenderam quando eu pedi. Aos parceiros do LaPFiMC, em especial Hugo e Sergio, sempre solícitos quando eu precisei. À UFRN, instituição da qual faço parte a 6 anos. Ao CNPq e CAPES pelo suporte nanceiro. It is our choices, Harry, that show what we truly are, far more than our abilities. Albus Dumbledore -J.K. Rowling Integração das técnicas tape casting e magnetron sputtering para o desenvolvimento de sistemas multifuncionais moldáveis.

This research papers examines the state-of-the-art in the area of P2P networks/computation. It attempts to identify the challenges that confront the community of P2P researchers and developers, which need to be addressed before the potential of P2P ...

Litecoin is a peer to peer internet crypto digital currency protocol held electronically that gains fame in the recent days. It is transferred electronically with a very low transaction fees without the help of any financial organizations. In this paper, online transaction from one person to another is studied in peer to peer networks with reduced transaction time. Here, a block chain distribution in bit-torrent network is considered to transact the litecoins. This method aims at gathering information on network size, number of client and network distributions. In this minimal structure network, broadcasted messages and nodes can rejoin or leave the network based on best effort basis. Finally, efforts are considered to avoid double spending attacks on litecoins.

Routing in a Peer-to-Peer environment faces a number of challenges, mainly due to its distributed nature. In this paper we evaluate a new distributed hash table architecture that is able to provide efficient routing through a fixed-size table. By introducing a set of base algorithms, multiple replication schemas, virtual nodes and a variable repair mechanism, we are able to ensure successful lookups of published keywords. Along with theoretical analysis of our proposed work, we present extensive simulation results that testify and evaluate our protocol.

Routing in a Peer-to-Peer environment faces a number of challenges, mainly due to its distributed nature. In this paper we evaluate a new distributed hash table architecture that is able to provide efficient routing through a fixed-size table. By introducing a set of base algorithms, multiple replication schemas, virtual nodes and a variable repair mechanism, we are able to ensure successful lookups of published keywords. Along with theoretical analysis of our proposed work, we present extensive simulation results that testify and evaluate our protocol.

Regular E-voting systems for elections may count the votes in less time,less cost,save the privacy of citizens,but still considered risky as votes can be tampered.E-voting systems based on a network distributed ledger show fast results,more trusted,save privacy,cannot be tampered,and distributed in which no central organization controls the system.This paper illustrate an e-voting system to solve the challenge of a massive ledger that is distributed among network-nodes using a data reduction technique as a security-matching-tool,singular value decomposition(SVD) that handle a copy of election results in another form and matched with the SQL-database results to announce a successful election-event representing a transparency-powerful-secured-system

This study presents an innovative approach using the Ethereum blockchain to democratize access to tutoring services, advancing educational technology by bridging the affordability gap for learners with limited financial resources. This solution enables low-income learners to access tutoring services without significant expenses by eliminating intermediaries through smart contracts. Learners can directly book tutoring services based on fees and evaluations, ensuring a fair and accessible experience. The findings show that this approach reduces tutoring expenses and improves trust and accountability through transparent transactions and feedback mechanisms. The proposed system demonstrates how blockchain technology can foster a more equitable and efficient educational landscape, offering personalized support to all learners regardless of their economic background.

Bitcoin is a "crypto currency", a decentralized electronic payment scheme based on cryptography. It implements a particular type of peer-to-peer financial anarchy. It has very recently gained excessive popularity and attracted a lot of attention in the mainstream press and media. Scientific research on this topic is less abundant. A paper at Financial Cryptography 2012 conference explains that Bitcoin is a system which uses no fancy cryptography, and is by no means perfect . Bitcoin depends on well-known cryptographic standards such as SHA-256. In this paper we revisit the cryptographic process which allows one to make money by producing new bitcoins. We reformulate this problem as a specific sort of Constrained Input Small Output (CISO) hashing problem and reduce the problem to a pure block cipher problem, cf. Fig. . We estimate the speed of this process and we show that the amortized cost of this process is less than it seems and it depends on a certain cryptographic constant which is estimated to be at most 1.89. These optimizations enable bitcoin miners to save tens of millions of dollars per year in electricity bills. Miners who set up mining operations face many economic incertitudes such as high volatility. In this paper we point out that there are fundamental incertitudes which depend very strongly on the bitcoin specification and that this is specification is NOT written in stone. The energy efficiency of bitcoin miners have already been improved by a factor of about 10,000 since bitcoin have been invented, and we claim that further improvements are inevitable. Better technology is bound to be invented, would it be quantum bitcoin miners. More importantly, the specification of the problem to solve is likely to change. A major change in the Proof of Work function have been proposed in May 2013 at Bitcoin conference in San Diego by Dan Kaminsky . However, any sort of change could be flatly rejected by the community which have heavily invested in ASIC mining with the current technology. Another question is the reward halving scheme in bitcoin. The current bitcoin specification mandates a strong 4-year cyclic property. This cycle is totally artificial and is simply an artifact of the current specification. We find this property totally unreasonable and harmful and explain why and how it needs to be changed.

Recent studies have reported a new form of malicious behavior in file-sharing Peer-to-Peer systems: content pollution. The dissemination of polluted content in a P2P system has the detrimental effect of reducing content availability, and ultimately, decreasing the confidence of users in such systems. Two potential strategies for polluting P2P content are decoy insertion, which consists of injecting corrupted copies of a file into the system, and hash corruption, which consists of injecting a corrupted file with the same hash code as a non-corrupted one. Polluted content disseminates through P2P networks because users typically do not delete the corrupted files that they download. This paper investigates the effectiveness of peer incentives to delete corrupted files in reducing the dissemination of polluted content, considering the two aforementioned pollution mechanisms. Our simulation results show that the effectiveness of incentives is highly dependent on the pollution mechanism. We show that for a pollution dissemintation techinique called hash corruption, only effective incentive mechanisms are able to avoid spreading of polluted content.

Peer-to-peer applications produce nowadays a significant fraction of the whole Internet traffic. The peerto-peer paradigm is not only used for file sharing and content dissemination but also for live video broadcasting, multiparty interactive gaming, as well as for large scale VoIP and teleconferencing applications. Existing peer-to-peer applications and protocols have been designed for peers running in normal PCs equipped with a broadband connection to the Internet. However, the emerging scenario is much more complex and heterogeneous, including a variety of terminals (PDAs, NAS boxes, etc.) and access networks (xDSL, Wi-Fi, WiMax, Wireless Mesh Networks, etc.). Simulation has been the most widely used approach for performance evaluation of peer-to-peer applications because it represents a fast and inexpensive way to test novel solutions. Nonetheless, the growing complexity and heterogeneity of the emerging scenario for peerto-peer applications has made it necessary to validate models and simulation results through experimental evaluation in realistic settings. This need is testified by the recent trend of conducting evaluation of peer-topeer applications in large scale testbeds (e.g. Planet-Lab) as well as in the real world (e.g. by collecting data R. Canonico (B)

Ride Sharing has seen a steep rise in popularity in metropolitan cities to avoid wastage of resources, traffic jams and congestions. This gave birth to a whole new trend which ride aggregator services went on to capitalize by providing the option of sharing cabs to its users at a lower price. Although conventional ride sharing methods have proven to be quite effective, there is always scope for improvement in certain fields. This idea of vehicle sharing can be revolutionized by implementing blockchain technologies. Blockchain is a decentralized record where all the information is stored on systems everywhere which can be retrieved and traced freely. There is a mechanism that allows peer to peer transactions and brings the need for third parties to an absolute minimum. The system is no longer trust-based but simply based on concrete proof that exists which is built into the ledger.

Fraud in health insurance claims poses a significant challenge to the modern healthcare industry, leading to substantial financial losses and undermining the trust in health insurance systems. This research paper introduces an innovative approach to fraud detection in health insurance claims by integrating blockchain technology with machine learning algorithms. The blockchain framework provides a secure, transparent, and immutable ledger for health insurance data, while machine learning models enhance the detection of fraudulent patterns and anomalies within claims data. This study outlines a comprehensive methodology, detailing the design, development, and implementation of a blockchain-based system for managing health insurance claims, integrated with advanced machine learning techniques for fraud detection. The mathematical foundations underpinning the proposed models are rigorously detailed, and the system's performance is evaluated through extensive experimental analysis. Our findings indicate that the integrated approach significantly improves the accuracy and reliability of fraud detection in health insurance claims, offering a valuable solution for stakeholders in the healthcare sector.

Group key management (GKM) is one of the most important issues in secure group communication (SGC). The existing GKM protocols fall into three typical classes: centralized group key distribution (CGKD), decentralized group key management (DGKM), and distributed/contributory group key agreement (CGKA). Serious problems remains in these protocols, as they require existence of central trusted entities (such as group controller or subgroup controllers), relaying of messages (by subgroup controllers), or strict member synchronization (for multiple round stepwise key agreement), thus suffering from the single point of failure and attack, performance bottleneck, or misoperations in the situation of transmission delay or network failure. We proposed a new class of GKM protocols: distributed group key distribution (DGKD) [1]. The new DGKD protocol solves the above problems and surpasses the existing GKM protocols in terms of simplicity, efficiency, scalability, and robustness. In this paper, we extend the conference paper [1] with detailed experiments and discussions. Also based on DGKD, we propose a new distributed dynamic conferencing scheme which enforces group/conference membership management. Due to its distributed feature without the requirement of a central control, the proposed scheme is well suited in wireless networks such as Mobile Ad-hoc Networks (MANETs).

Supply chains (SC) span many geographies, modes and industries and involve several phases where data flows in both directions from suppliers, manufacturers, distributors, retailers, to customers. This data flow is necessary to support critical business decisions that may impact product cost and market share. Current SC information systems are unable to provide validated, pseudo real-time shipment tracking during the distribution phase. This information is available from a single source, often the carrier, and is shared with other stakeholders on an as-needed basis. This paper introduces an independent, crowd-validated, online shipment tracking framework that complements current enterprise-based SC management solutions. The proposed framework consists of a set of private distributed ledgers and a single blockchain public ledger. Each private ledger allows the private sharing of custody events among the trading partners in a given shipment. Privacy is necessary, for example, when trading high-end products or chemical and pharmaceutical products. The second type of ledger is a blockchain public ledger. It consists of the hash code of each private event in addition to monitoring events. The latter provide an independently validated immutable record of the pseudo real-time geolocation status of the shipment from a large number of sources using commuters-sourcing.

A indústria do turismo, outrora um dos principais propulsores da economia de diversas nações, enfrenta uma grave crise global decorrente da pandemia de covid-19 e da consequente limitação da circulação de pessoas entre países. A diversicação da oferta turística cultural de um país ou região, através de novas abordagens, pode estimular os turistas nacionais a (re)visitar os lugares da sua memória cultural, e assim contribuir para dinamizar a indústria do próprio país. Neste artigo apresenta-se a aplicação (app) para dispositivos móveis, guia virtual RAM Tomar 1930-1965, orientada para o setor do turismo cultural. A app foi desenvolvida por uma equipa pluridisciplinar do Instituto Politécnico de Tomar, com o objetivo de divulgar o património arquitetónico modernista existente na cidade e projetado entre 1930 e 1965.

Time banks (TBs) have experienced significant growth in the last few years in Spain and have been incorporated in the agenda of political parties drawing the attention of national and international media as a solution to the economic crisis. Nevertheless, there is scant empirical evidence about this phenomenon in Spain. After describing the role of TBs in other countries, this paper examines the structure and management of TBs in Spain and develops a taxonomy of them. Additionally, it identifies the goals TBs pursue and the reasons why users join them. To do so, this paper uses a mixedmethod approach consisting of in-depth interviews with 28 TB managers and an online survey of users (n=270). It concludes that TBs are a social-political project rather than a utilitarian-economic project, identifying differences between Spanish TBs and those in other countries.

Peer-to-peer applications produce nowadays a significant fraction of the whole Internet traffic. The peerto-peer paradigm is not only used for file sharing and content dissemination but also for live video broadcasting, multiparty interactive gaming, as well as for large scale VoIP and teleconferencing applications. Existing peer-to-peer applications and protocols have been designed for peers running in normal PCs equipped with a broadband connection to the Internet. However, the emerging scenario is much more complex and heterogeneous, including a variety of terminals (PDAs, NAS boxes, etc.) and access networks (xDSL, Wi-Fi, WiMax, Wireless Mesh Networks, etc.). Simulation has been the most widely used approach for performance evaluation of peer-to-peer applications because it represents a fast and inexpensive way to test novel solutions. Nonetheless, the growing complexity and heterogeneity of the emerging scenario for peerto-peer applications has made it necessary to validate models and simulation results through experimental evaluation in realistic settings. This need is testified by the recent trend of conducting evaluation of peer-topeer applications in large scale testbeds (e.g. Planet-Lab) as well as in the real world (e.g. by collecting data R. Canonico (B)

Video on Demand (VOD) system over the wireless mobile network is a system that provides video services to mobile clients. The main problem with these systems is the high service delay where the mobile clients have to wait to view their favorite movie. The importance of this paper is based on finding a solution on how to reduce the delay time in the VOD system. This paper introduces a novel caching mechanism named Proxy Server Cache mechanism to tackle the issue of service delay. This delay happens when the broadcasting phase that is related to the first segment is missed by a client from the current broadcasting channels. In this mechanism, the video's first segment is stored on a server of a stationary proxy type. The delayed clients will directly acquire the first segment from the proxy server instead of waiting for the following broadcasting channel pertaining to the first segment. The proposed scheme ensuresobtaining the first segment from mobile clients when they arrive. Additionally, the performance of the proposed scheme is validated by applying the VOD system, which can involve the balancing mechanism to retain particular requests through to the local proxy server to provide a fair dissemination for these requests. The obtained result confirms that the proposed scheme reduces the time delay of the system in comparison with the best existing schemes. The results of the average time delay in the Proxy-Cache scheme is 179.2505 milliseconds when 10 clients arrive each minute (Client/minute), the average time delay is 140 milliseconds when the video lengths are 30, 60 and 90. Meanwhile, the failure probability for obtaining the first segment of the video remains zero when the number of arrived requests is set to2, 4, 6, 8 and 10.

Rackoff and Simon proved that a variant of Chaum's protocol for anonymous communication, later developed as the Onion Routing Protocol, is unlinkable against a passive adversary that controls all communication links and most of the nodes in a communication system. A major drawback of their analysis is that the protocol is secure only if (almost) all nodes participate at all times. That is, even if only n N nodes wish to send messages, all N nodes have to participate in the protocol at all times. This suggests necessity of sending dummy messages and a high message overhead. Our first contribution is showing that this is unnecessary. We relax the adversary model and assume that the adversary only controls a certain fraction of the communication links in the communication network. We think this is a realistic adversary model.

Peer-to-Peer (P2P) networking emerged as a disruptive business model displacing the server based networks within a point in time.P2P technologies are on the edge of becoming all-purpose in developing several applications for social networking. In the past seventeen years, research on P2P computing and systems has received enormous amount of attention in the areas of academia and the industry. P2P rose to triumphant profit-making systems in the internet. It represents the best incarnation of the end to end argument, the frequently disputed design philosophies that guided the design of the internet. The doubting factor then is why is research on P2P computing now fading from the spotlight and suffering a nose dive fall as dramatic as its rise to its popularity. This paper is going to capture a quick look at past results in peer-to-peer computing with focus on understanding what led to its rise, what contributed to its commercial success and what has led to its lack of interest. The insight of this paper introduces cloud computing as a paradigm to peer-to-peer computing.

A diploma is a certificate or official document given by a school or college that is useful for continuing education, applying for jobs, and assessing student intelligence. The main problem with diplomas and other academic documents is that many are forged. This study aims to develop a prototype for recording student academic data using blockchain and blockchain and InterPlanetary file system (IPFS). The research stages were conducted with system conceptualization, data modeling, smart contract development, IPFS integration, data transaction development, user interface/user experience (UI/UX) development, and system testing. A blockchain is a permanent information structure formed by data blocks that are interconnected with transaction data blocks before and after it. The transaction data for each block are encrypted using asymmetric cryptography. IPFS is a peer-to-peer network protocol for storing and sharing data in a distributed file system applying the concept of decentralization to make the manipulation more difficult. The results show that student academic data and documents were successfully stored in a blockchain network using smart contracts and IPFS. Blockchain technology, smart contracts, and IPFS strengthen the value of these documents into documents that are safe, difficult to counterfeit, and easy to trace, such that authentication and integration are better preserved.

The simplicity with which products and prices are compared in e-commerce has introduced an attractive option for many online merchants. The completion of online business transactions with personal information provisioning has always been an act that beckons hesitation. Most online traders are highly conscious of various threats and attacks such as credit card fraud, identity theft, spoofing, hacking, phishing, and other abuses, leading to low trust in online business transactions. Online transactions take place among Peer-to-Peer (P2P) systems at the edge of the Internet. Peer communities are often established dynamically with peers that are unrelated and unknown to each other. In our proposed mechanism, peers form groups in order to ensure trust and security. Each group is established based on interest among peers. In this paper, we show how peers form groups, and select group leaders. A peer can belong to more than one group. Comparing with some existing work, our work reveals that peers can have common neighbors which have a similarity based on their interest. Our simulation results show that the model can deal with the malicious attacks efficiently by comparison with existing models.

The existence of a high degree of free riding is a serious threat to Peer-to-Peer (P2P) networks. In this paper, we propose a distributed framework to reduce the adverse effects of free riding on P2P networks. Our solution primarily focuses on locating free riders and taking actions against them. We propose a framework in which each peer monitors its neighbors, decides if they are free riders, and takes appropriate actions. Unlike other proposals against free riding, our framework does not require any permanent identification of peers or security infrastructures for maintaining a global reputation system. Our simulation results show that the framework can reduce the effects of free riding and can therefore increase the performance of a P2P network.

The growth of crowdsourced platforms for consumer products has opened many interesting research questions on the impact of consumers participating in such crowdsourced work. In this paper, we focus on consumers' psychological ownership of the crowdsourced product and the role it plays in the relationship between consumer work and consumer citizenship. Further, drawing on social comparison theory, we show that consumers' perceived amount of work relative to others is a boundary condition for this explanation. Finally, we examine the theoretical contributions and managerial implications of our findings.

The growth of crowdsourced platforms for consumer products has opened many interesting research questions on the impact of consumers participating in such crowdsourced work. In this paper, we focus on consumers' psychological ownership of the crowdsourced product and the role it plays in the relationship between consumer work and consumer citizenship. Further, drawing on social comparison theory, we show that consumers' perceived amount of work relative to others is a boundary condition for this explanation. Finally, we examine the theoretical contributions and managerial implications of our findings.

Health information portals (HIP) are now common place. Governments and other health agencies are using HIPs extensively to reduce costs and distribute information more effectively. Generally, HIPs are not very technically sophisticated specifically in terms of options for improving searching. There are many ways in which searching and retrieving relevant information can be improved. This paper presents an exploratory study which investigated five HIPs. Each HIP offered a range of features and functionality to assist with searching. Our research explored the features and functionality of each HIP. Through usability evaluations we compared the response of users to each HIP and identified users' preferences for improved searching. We found that HIPs with improved search functionality and other features that assisted searching were better received by the users. Users regarded these portals as easier to understand, easier to use, required fewer steps in retrieving information and were more likely to say they would return. Comments from users are provided to illustrate further the importance of providing effective functionality. The paper concludes with recommendations for Health Information Portal builders on what is needed to improve the user search experience.

Progress in medicine hinges on the successful translation of basic science discoveries into new medical devices, diagnostics, and therapeutics. "Technology transfer" is the process by which new innovations flow from the basic research bench to commercial entities and then to public use. In academic institutions, intellectual property rights do not usually fall automatically to the individual inventor per se, but most often are the property of the institution. Technology transfer offices are tasked with seeing to it that such intellectual property rights are properly managed and commercialized. This 2-part series explores the technology transfer process from invention to commercialization. Part 1 reviews basic aspects of intellectual property rights, primarily patents and copyrights. Part 2 will discuss the ways in which inventions become commercialized through startup companies and licensing arrangements with industry players.

We propose a strategy to perform query processing on P2P similarity search systems based on peers and superpeers. We show that by approximating global but resumed information about the indexed data in each peer, the average amount of computation and communication performed to solve range queries can be significantly reduced as compared to alternative state of the art strategies based on local indexing at peer level. We illustrate our technique by using an indexing method based on compact clustering.

In recent times, consumer-to-consumer exchange networks have gained popularity. In these exchange systems members may adopt different roles as producers or as consumers of products and services. Furthermore, the participation in such systems may aim to achieve utilitarian or political and social goals. In this paper we focus on a particular type of consumerto-consumer exchange system, timebanking. We posit that goals influence different forms of participation in these networks: political and social goals drive membership but economic goals lead to exchanges. We find confirmation for this assumption in a dataset of 255 self-administered questionnaires to members of Spanish timebanks. In particular, our contribution lies on further understanding the nature and intensity of members' participation in consumer-to-consumer exchange systems, such as timebanking, in relation to the goals they set. We conclude that to better understand consumer-to-consumer exchange networks it is essential to, first, unbundle the membership from the carried-out transactions, and second, to separate the two roles that members perform in consumer-to-consumer markets as the goals attached to these may vary. Political goals may drive membership but not transactions.