Blockchain Papers

Kombe Kaponda

No abstract is available for this record.

GİZEM KIZILBEY

2008 yılında yayınlanan "Bitcoin: A Peer-to-Peer Electronic Cash System" adlı makale sayesinde bilgi sahibi olduğumuz Bitcoin, bilimsel litaratüre yeni terimler kazandırarak popülerliğini arttırmaktadır. Alternatif sanal para olarak geliştirilen Ethereum, merkezi bir sunucu veya bir kontrol noktaya ihtiyaç duymadan, karşılıklı uçlar arası anonim ve ucuz şekilde varlık transferine olanak sağlayan bir sistemdir. Blokzincir yapısının en yaygın kullanımı olan Bitcoin ve altcoinlerdir. Kripto paralar madencilik olarak adlandırılan ve zorlu bir algoritmanın çözümü ile gerçekleşmektedir. Sistemde yer alan herhangi bir madenci bu çözümü elde etmek için elinde bulunan ekran kartı ve işlemci gücünü kullanmaktadır. Bu çalışmada GPU'ların barındırdığı işlemcilerin, kayan noktalı işlem hesaplamalarında daha verimli olmaları sebebiyle Ethereum madenciliğinde kullanılan çeşitli ekran kartlarının performansları 4 kademeli bir iyileştirme paketi ile artırılarak karşılaştırılmıştır. Önerilen iyileştirme metotları için kullanılan ekran kartlarının model ve bellek miktarları şu şekildedir: 4 GB AMD R9 290, 4 GB AMD R9 380, 8 GB AMD R9 390, 4 GB AMD RX 560, 4 GB AMD RX 470, 4 GB AMD RX 480, 4 GB AMD RX 570, 4 GB AMD RX 580, 6 GB NVIDIA GTX1060, 8 GB NVIDIA GTX1070, 8 GB NVIDIA GTX1080. Bu çalışmanın en önemli amacı, Ethereum madenciliğine özgü Ethash özet algoritmasında iyileştirme yöntemleri uygulamaktır. Bu amaçla, AMD ve NVIDIA yonga seti grafik kartlarının daha düşük güç tüketimi ile daha hızlı algoritmalar çözmelerini sağlamak için iyileştirmeler yapılmıştır. Grafik kartları fabrika ayarlarıyla çalıştırıldığında, hiçbiri geçerli döviz kurlarından dolayı fayda getiremeyecek durumdadır. Algoritmanın hızını arttırmanın yanı sıra güç tüketimini azaltmak kar bölgesine geçiş için önemli bir faktör olmuştur. Yapılan çalışmalar sonucunda elde edilen değerlere bakıldığında yaklaşık % 30 performans artışı görülmüştür. Ayrıca iyileştirme paketi ile ekran kartlarının tükettiği elektrik enerjisi yüzde 20 ile yüzde 30 arası azaltılmıştır. Anahtar Kelimeler: Ethereum, Blokzincir, Kripto para madenciliği, GPU madenciliği

George Pickering

Given Bitcoin’s apparent lack of non-monetary uses, Luther (2018) argues that its emergence as a medium of exchange invalidates the regression theorem, or at least severely limits its relevance to identifying which commodities could emerge as media of exchange in the absence of State intervention. However, this view misinterprets both the regression theorem itself and the problem it was developed to address. The goal of the regression theorem was not to identify which commodities could become monies, but to provide a subjectivist explanation of the purchasing power of money. To do this, it requires only that some individuals valued the good in question before its use as a medium of exchange, not that it had some objective pre-monetary use.

Hlib Naumenko

Bitcoin is a top-ranked cryptocurrency that has experienced huge growth and survived numerous attacks. The protocols making up Bitcoin must therefore accommodate the growth of the network and ensure security. However, Bitcoin’s transaction dissemination protocol has mostly evaded optimization. This protocol is based on flooding and though it is secure and fault-tolerant, it is also highly inefficient. Specifically, our measurements indicate that 43% of the traffic generated by transaction dissemination in the Bitcoin network is redundant. In this paper we introduce a new transaction dissemination protocol called Erlay. Erlay is a hybrid protocol that combines limited flooding with intermittent reconciliation. We evaluated Erlay in simulation and by implementing and deploying it at scale. Compared to Bitcoin’s current protocols, Erlay reduces the bandwidth used to announce transactions by 84% without significantly affecting privacy or propagation speed. In addition, Erlay retains the existing Bitcoin security guarantees and is more scalable relative to the number of nodes in the network and their connectivity. Erlay is currently being investigated by the Bitcoin community for future use with the Bitcoin protocol.

Αλεξάνδρα Γιαννοπούλου, Valeria Ferrari

Blockchains and the GDPR pursue similar objectives where they seek to grant users greater control over their personal data. While the latter pursues this goal by imposing duties of care to centralised controllers and collectors of data, blockchains go a step beyond by trying to eliminate these stakeholders and the need to trust them. Nevertheless, the rules set out by the GDPR apply whenever personal data are at stake, and various actors of the blockchain ecosystem risk liability for controlling of processing data in violation of privacy requirements. A possible solution is to re-contextualise the concepts of data controlling and responsibility, as framed by the GDPR, in light of blockchains’ enhanced individual autonomy. In this paper, we set the framework for a further inquiry on the role of users as both data subjects and data controllers of distributed ledgers.

Luca Enriques, Dirk Andreas Zetzsche

No abstract is available for this record.

Bushra Hameed, Muhammad Murad, Abdul Noman, Muhammad Umar Javed · 8 authors

Blockchain is a decentralized and shared dis-tributed ledger that records the transaction history done by totally different nodes within the whole network. The technology is practically used in the field of education for record-keeping, digital certification, etc. There have already been several papers published on this, but no one can’t find a single paper covering the blockchain-based educational projects. So, There is a gap of latest trends to education. Blockchain-based educational projects resolve the issues of today’s educators. On that basis, we conclude that there is a need for conducting a systematic literature review. This study, therefore, reviews the artistic gap between these two based on educational projects. For this purpose, the paper focuses on exploring some block-chain based projects and protocols that are used in these projects. It also analyses the block-chain features that are being used and the services are offered by the existing educational projects using block-chain features to improve the execution of this technology in education.

Yiming Wu, Shaohua Tang, Bowen Zhao, Zhiniang Peng

Task matching in crowdsourcing is designed to provide convenient task information retrieval and has been extensively explored. In general, the task matching process is required to be reliable and to meet privacy requirements. However, most existing privacy-preserving task matching solutions for crowdsourcing focus on privacy issues but ignore the reliability of the process. In this paper, we propose a blockchain-based task matching scheme for crowdsourcing with a secure and reliable matching. Instead of utilizing a centralized cloud server, we employ smart contracts, an emerging blockchain technology, to provide reliable and transparent matching. In this way, data confidentiality and identity anonymity are achieved effectively and efficiently. The extensive privacy analysis and performance evaluation show that our solution is secure and feasible.

Charalampos Alexopoulos, Yannis Charalabidis, Aggeliki Androutsopoulou, Michalis Avgerinos Loutsaris · 5 authors

Nowadays, Blockchain Technologies (BCT) could be characterized as one of the most promising trends. We are currently witnessing a plethora of implementations basically in the economic sector with the creation of cryptocurrencies. The majority of researchers and practitioners argues that many benefits could be derived from the use of this innovative technology with the most significant one being the improved sense of trust to BCT applications. At the same time governments pursue amplified trust from their citizens and BCT is gaining momentum since it addresses this of utmost importance problem based on its unique characteristics. More and more governments realize the advances of this technology and participate in pilot applications in different vertical governmental sectors. Even though there are several implementations in the Government sector, there is no comprehensive study towards the analysis of the major characteristics of these developments. This paper moves towards the fulfilment of this gap conducting a thorough analysis of e-Government pilot applications of BCT in a European level. Furthermore, this study discusses the key benefits and main barriers coming from the application of this technology in different domains with BCT experts.

Andreas Kamilaris, Ian R. Cole, Francesc X. Prenafeta‐Boldú

Blockchain is an emerging digital technology allowing ubiquitous financial transactions among distributed untrusted parties, without the need of intermediaries such as banks. This chapter examines the impact of blockchain technology in agriculture and food supply chain, presents existing ongoing projects and initiatives, and discusses overall implications, challenges and potential, with a critical view over the maturity of these projects. Our findings indicate that blockchain is a promising technology towards a transparent supply chain of food, with many ongoing initiatives in various food products and food-related issues, but many barriers and challenges still exist, which hinder its wider popularity among farmers and systems. These challenges involve technical aspects, education, policies and regulatory frameworks.

Jiasi Weng, Jian Weng, Jilian Zhang, Ming Li · 6 authors

Deep learning can achieve higher accuracy than traditional machine learning algorithms in a variety of machine learning tasks. Recently, privacy-preserving deep learning has drawn tremendous attention from information security community, in which neither training data nor the training model is expected to be exposed. Federated learning is a popular learning mechanism, where multiple parties upload local gradients to a server and the server updates model parameters with the collected gradients. However, there are many security problems neglected in federated learning, for example, the participants may behave incorrectly in gradient collecting or parameter updating, and the server may be malicious as well. In this article, we present a distributed, secure, and fair deep learning framework named DeepChain to solve these problems. DeepChain provides a value-driven incentive mechanism based on Blockchain to force the participants to behave correctly. Meanwhile, DeepChain guarantees data privacy for each participant and provides auditability for the whole training process. We implement a prototype of DeepChain and conduct experiments on a real dataset for different settings, and the results show that our DeepChain is promising.

Diana Kovalchuk, Т. I. Іvko, Tetiana Kuznetsova, Oleksii Nariezhnii

The categories of popular consensus punctures are reviewed: Proof of Work and its hybrids, Proof of Stake (includes LPoS, Proof of Importance) and hybrids, DAGs and its varieties. The article describes their algorithms, characteristics, features, as well as disadvantages and advantages. Vulnerabilities and attacks are subject to. Also provides a list of the use of each protocol in cryptocurrencies and other systems.

Christoph H.-J. Braun, Tobias Käfer

We present an approach to verify off-chained information using Linked Data, Smart Contracts, and RDF graph hashes stored on a Distributed Ledger. We use the notion of a Linked Pedigree, i.e. a decentralised dataset for storing hyperlinked information, as modelling foundation. We evaluate our approach by comparing different ways to build the Smart Contract. We develop a cost model and show, based on our implementation, that for managing multiple Linked Pedigree instances, a single larger Smart Contract is superior to multiple smaller Smart Contracts for supply chains shorter than 50 participants.

Quinn DuPont

This article investigates ethical research risks associated with cryptocurrencies and the related family of digital "value" technologies. It provides an empirical analysis of innovation and recommends guiding principles for ethical research and development. Ethical research risks are identified through 1) an analysis of research methods and ethics disclosure practices in published empirical research; and 2) a survey of academic research practices and researcher opinions. These data identified multiple research ethics issues. It was discovered that most researchers have extensive and undisclosed industry relationships, have undisclosed conflicts of interest arising from token ownership, and report low use of institutional review or ethics guidelines, among other issues. Three novel research risks-conflicts of interest, risky methods, and disclosure-are then introduced and compared to the risks of conventional research. It is argued that these technologies introduce ethical risks and opportunities beyond their sector. These findings suggest a new class of ethical and normative research practice, comparable to fields such as bio-or nanotechnology ethics. Based on these analyses, eight principles for ethical research are described, with practical lessons for the researcher.

Ghada Almashaqbeh

Online content delivery has witnessed dramatic growth recently with traffic consuming over half of today’s Internet bandwidth. This escalating demand has motivated content publishers to move outside the traditional solutions of infrastructure-based content delivery networks (CDNs). Instead, many are employing peer-to-peer data transfers to reduce the service cost and avoid bandwidth over-provision to handle peak demands. Unfortunately, the open access work model of this paradigm, which allows anyone to join, introduces several design challenges related to security, efficiency, and peer availability. In this dissertation, we introduce CacheCash, a cryptocurrency-based decentralized content distribution network designed to address these challenges. CacheCash bypasses the centralized approach of CDN companies for one in which end users organically set up new caches in exchange for cryptocurrency tokens. Thus, it enables publishers to hire caches on an as-needed basis, without constraining these parties with long-term business commitments. To address the challenges encountered as the system evolved, we propose a number of protocols and techniques that represent basic building blocks of CacheCash’s design. First, motivated by the observation that conventional security assessment tools do not suit cryptocurrency-based systems, we propose ABC, a threat modeling framework capable of identifying attacker collusion and the new threat vectors that cryptocurrencies introduce. Second, we propose CAPnet, a defense mechanism against cache accounting attacks (i.e., a client pretends to be served allowing a colluding cache to collect rewards without doing any work). CAPnet features a bandwidth expenditure puzzle that clients must solve over the content before caches are given credit, which bounds the effectiveness of this collusion case. Third, to make it feasible to reward caches per data chunk served, we introduce MicroCash, a decentralized probabilistic micropayment scheme that reduces the overhead of processing these small payments. MicroCash implements several novel ideas that make micropayments more suitable for delay-sensitive applications, such as online content delivery. CacheCash combines the previous techniques to produce a novel service-payment exchange protocol that secures the content distribution process. This protocol utilizes gradual content disclosure and partial payment collection to encourage the honest collaborative work between participants. We present a detailed game theoretic analysis showing how to exploit rational financial incentives to address several security threats. This is in addition to various performance optimization mechanisms that promote system efficiency and scalability. Lastly, we evaluate system performance and show that modest machines can serve/retrieve content at a high bitrate with minimal overhead.

Dominik Harz, Lewis Gudgeon, Arthur Gervais, William J. Knottenbelt

Financial deposits are fundamental to the security of cryptoeconomic protocols as they serve as insurance against potential misbehaviour of agents. However, protocol designers and their agents face a trade-off when choosing the deposit size. While substantial deposits might increase the protocol security, for example by minimising the impact of adversarial behaviour or risks of currency fluctuations, locked-up capital incurs opportunity costs. Moreover, some protocols require over-collateralization in anticipation of future events and malicious intentions of agents. We present Balance, an application-agnostic system that reduces over-collateralization without compromising protocol security. In Balance, malicious agents receive no additional utility for cheating once their deposits are reduced. At the same time, honest and rational agents increase their utilities for behaving honestly as their opportunity costs for the locked-up deposits are reduced. Balance is a round-based mechanism in which agents need to continuously perform desired actions. Rather than treating agents' incentives and behaviour as ancillary, we explicitly model agents' utility, proving the conditions for incentive compatibility. Balance improves social welfare given a distribution of honest, rational, and malicious agents. Further, we integrate Balance with a cross-chain interoperability protocol, XCLAIM, reducing deposits by 10% while maintaining the same utility for behaving honestly. Our implementation allows any number of agents to be maintained for at most 55,287 gas (ca. USD 0.07) to update all agents' scores, and at a cost of 54,948 gas (ca. USD 0.07) to update the assignment of all agents to layers.

Alexander Brauneis, Roland Mestel, Ryan Riordan, Erik Theissen

No abstract is available for this record.

Soehartono, U. Khaerah Pati

No abstract is available for this record.

Peder Østbye

No abstract is available for this record.

Leyi Shi, Yang Li, Tianxu Liu, Jia Liu · 6 authors

Honeypot technology can be applied to efficiently attract attackers and exhaust their resources. However, the traditional static honeypot is easy to be recognized by anti-honeypot technology. By contrast, most of the dynamic honeypots can simulate the real system in time, thus interacting with an intruder in disguise. In this paper, we employ the dynamic property of honeypot in four kinds of services of our system. However, this dynamic property shows up in a location and identification, indicating that genuine or fake services (honeypots) are changeable in different hosts. Thus, the dynamic property of our system differs from the dynamic honeypot aforementioned. Besides, we adopt the blockchain platform (Ethereum) to decentralize our system and store the port access data by delivering a private chain. To illustrate the effectiveness of our scheme in theory and practice, security analysis, eavesdropping attack, scanning attack, and DoS attack experiments are conducted. The results show that our scheme is valid in safeguarding against network attack.

Yasser Mustafa

No abstract is available for this record.

Andrea Podhorsky

No abstract is available for this record.

Akanksha Jalan, Roman Matkovskyy, Andrew Urquhart

No abstract is available for this record.

Ravi Kumar, H.L. Gururaj, Manoj Athreya A, Nagarajath S. M · 5 authors

As the whole world is moving towards digital payments, ethers and the transaction methods with quick payment features are stored in a blockchain in a distributed network. To adopt pet animals, this technology provides security and flexibility to users. The distributed network is a network system through which data, software and computer programming are spread across on more than one node(computers) and these nodes are dependent on each other. It is nothing but a peer-to-peer network which eliminates a single point of failure. The blockchain is a growing list of records called blocks, that are linked using cryptography. It is a decentralised, distributed and an immutable ledger to store digital transactions. Its databases are managed using a peer-to-peer network where all the nodes in a network are equal and are the major concern in the types of network architecture. The consensus protocol is used for transacting and communicating between the nodes. In this paper, a unique way of adopting pets is proposed where the transaction details are stored in a blockchain whereby using hash value returns further details of the transaction. It provides users more convenient access in adopting pets and provides a better approach to the existing centralised system.