Blockchain Papers

Burcu Kapar, José Olmo

No abstract is available for this record.

Karl J. Kreder

Blockchains have shown great promise as peer-to-peer digital currency systems over the past 10 years. However, with increased popularity, the demand for processing transactions has also grown leading to increased costs, confirmation times, and limited blockchain utility. There have been a number of proposals on how to scale blockchains, such as Plasma, Polkadot, Elastico, RapidChain, Bitcoin-NG, and OmniLedger. These solutions all propose the segmentation of every function of a blockchain, namely consensus, permanent data storage, transaction processing, and consistency, which significantly increases the complexity and difficulty of implementation. BlockReduce is a new blockchain structure which only segments consistency, allowing it to scale to handle tens of thousands of transactions per second without impacting fault tolerance or decentralization. Moreover, BlockReduce will significantly decrease node bandwidth requirements and network latency through incentives while simultaneously minimizing other resource demands in order to prevent centralization of nodes.

Ebenezer M. Ashley

In January 2009, the whole world was introduced to a new financial invention called Bitcoin. This coin is intended to accelerate globalisation of the financial market. Significantly, the inventor is credited as the first to succeed in solving the double-spending challenges associated with digital currency. Prior to the invention, a white paper about the bitcoin was authored and released in 2008under the name, Satoshi Nakamoto. However, the name, Satoshi Nakamoto, remains a mystery; the original inventor of the bitcoin remains a mirage to the financial world. Some analysts believe a pseudonym, rather than an original name, was used in creating the bitcoin. The main purpose of this research was to assess the financial impact of crypto currency, specifically bitcoin, on the Ghanaian and other economies across the globe. The systematic exploratory technique, an example of the mixed methods approach to scientific inquiry, was adapted for this research. Data required for the conduct of this research were obtained mainly from secondary sources. These included text books, journals, newspaper publications, and digital currency markets.Findings from the research revealed divergent views on the prospects of bitcoins in the medium- and long-term: some experts believed a bitcoin would soon trade at 1BTC: US$12,000 while others believed the future of the digital currency cannot be predicted with relative ease, what would become of the bitcoin in the medium- and long-term. The findings revealed some price volatilities in the bitcoin market. This notwithstanding, the digital currency has made remarkable strides in value since 2009 till date. The study recommended the need for governments to introduce measures that would ensure anti-money laundering, and "know-your-customer” controls; reduce the level of anonymity and privacy to eventually minimise use of bitcoins in criminal activities. There is the need for intelligence agencies of governments to engage the services of individuals who are technologically savvy to understand, operate and control the bitcoin system, which is technologically more complex than most of the computer systems used in day-to-day operations in various organisations. Institutions of higher learning and professional bodies could integrate the study of crypto currency into individual business related programmes.

Hiroki Kuzuno, Giannis Tziakouris

Bitcoin is the leading cryptocurrency in the world with a total marketcap of nearly USD 33 billion, [1] with 370,000 transactions recorded daily[2]. Pseudo-anonymous, decentralized peer-to-peer electronic cash systems such as Bitcoin have caused a paradigm shift in the way that people conduct financial transactions and purchase goods. Although cryptocurrencies enable users to securely and anonymously exchange money, they can also facilitate illegal criminal activities. Therefore, it is imperative that law enforcement agencies develop appropriate analytical processes that will allow them to identify and investigate criminal activities in the Blockchain (a distributed ledger). In this paper, INTERPOL, through the INTERPOL Global Complex for Innovation, proposes a Bitcoin analytical framework and a software system that will assist law enforcement agencies in the real-time analysis of the Blockchain while providing digital crime analysts with tracing and visualization capabilities. By doing so, it is feasible to render transactions decipherable and comprehensible for law enforcement investigators and prosecutors. The proposed solution is evaluated against three criminal case studies linked to Darknet markets, ransomware and DDoS extortion.

Seoung Kyun Kim, Zane Ma, Siddharth Murali, Joshua Mason · 6 authors

Ethereum, the second-largest cryptocurrency valued at a peak of $138 billion in 2018, is a decentralized, Turing-complete computing platform. Although the stability and security of Ethereum---and blockchain systems in general---have been widely-studied, most analysis has focused on application level features of these systems such as cryptographic mining challenges, smart contract semantics, or block mining operators. Little attention has been paid to the underlying peer-to-peer (P2P) networks that are responsible for information propagation and that enable blockchain consensus. In this work, we develop NodeFinder to measure this previously opaque network at scale and illuminate the properties of its nodes. We analyze the Ethereum network from two vantage points: a three-month long view of nodes on the P2P network, and a single day snapshot of the Ethereum Mainnet peers. We uncover a noisy DEVp2p ecosystem in which fewer than half of all nodes contribute to the Ethereum Mainnet. Through a comparison with other previously studied P2P networks including BitTorrent, Gnutella, and Bitcoin, we find that Ethereum differs in both network size and geographical distribution.

Oğuzhan TAŞ, Farzad Kiani

Son zamanlarda; blok zinciri tabanlı kripto para ödeme sistemleri(bitcoin, ethereum) oldukça popüler olmuştur. Merkezi olmayan eşler arası(P2P) ağ yapısına sahip olan bu sistemde tüm işlemler, sadece ekleme yapılabilen bir ana defterde(ledger) tutulmaktadır. Madenciler ise bu ağ yapısındaki düğümleri oluşturmaktadır, her madenci defterin yerel kopyasına sahiptir. Blok zincirinde, PoW uzlaşma protokolü işlemi onaylamakta ve zincire yeni blok eklenmesine izin vermektedir. Ödülü almak için, madenciler eşler arası ağda işlemi tamamlamak için birbirleriyle yarışırlar. Ödül sistemi, blok zinciri kullanan bitcoin’i popülerleştirmiş, fakat aynı zamanda saldırganların blok zincirine ilgisini artırmıştır. Saldırganlar tarafından blok zincirinin madenci havuzuna ve ağ yapısının güvenliğine farklı saldırılar yapılmıştır. Bu makalede, blok zinciri alt yapısına karşı mevcut saldırılar sunulmuştur. İlk bölümlerde, P2P mimarisine, uzlaşma protokolüne ve işlemlere yönelik saldırı tipleri araştırılmıştır. Bu bölümde, %51 saldırısı, Çift harcama, Finney, Vector76, Kaba Kuvvet, Sybil, Eclipse, Denge gibi saldırılar açıklanmış ve çözümler önerilmiştir. Daha sonra, Bencil madencilik ve Blok Atma, Blok Tutma(BWH), Blok Tutma Sonrası Çatallanma(FAW), Havuz sıçrama saldırısı, Cezalandırıcı Çatallanma ile Kara Listeye Alma, Köpük saldırısı ve Rüşvet Saldırısı gibi madencilik havuzuna karşı saldırılar incelenmiş ve savunma stratejileri sunulmuştur. Son bölümde de blok zinciri altyapısında kullanılan kriptografi’nin geleceği üzerinde tartışılmış ve Post Kuantum Kriptografi’nin etkilerinden bahsedilmiştir

Jacek Binda

Money is a widely accepted commodity allowing to determine the economic value of purchased goods and services and to make payments. Over the centuries, "money" has been constantly evolving. In recent times, following dynamic development of various forms of e-business, dematerialized money has emerged. However, in constantly changing conditions it is very difficult to grasp the essence of the so called e-money or cryptocurrencies. The paper tries to define Bitcoin, one of the most recognizable cryptocurrencies, and answer the question whether investing in cryptocurrencies is a serious business or a mere gambling. In search for the answers, the author reviews literature on the topic and conducts his own risk analysis based on Value at Risk measure, of selected traditional currencies and Bitcoin. The results of the analysis unambiguously show that investments in Bitcoin are burdened with definitely much higher risk. Furthermore, conclusions of the considerations clearly show that despite growing popularity of cryptocurrencies they do not fulfill the definition of both electronic money or money in general. The paper attempts to discuss selected issues related to Bitcoin cryptocurrencies from the monetary point of view but also with respect to restrictions of Bitcoin as a means of payment, investments in Bitcoin and risk assessment.

Maxime Lambrecht, Louis Larue

How promising is Bitcoin as a currency? This paper discusses four claims on the advantages of Bitcoin: a more stable currency than state-backed ones; a secure and efficient payment system; a credible alternative to the central management of money; and a better protection of transaction privacy. We discuss these arguments by relating them to their philosophical roots in libertarian and neoliberal theories, and assess whether Bitcoin can effectively meet these expectations. We conclude that despite its advocates' enthusiasm, there are good reasons to doubt that Bitcoin can fulfill its promises and act as a functioning currency, rather than as a mere speculative asset.

Marc Jourdan, Sébastien Blandin, Laura Wynter, Pralhad Deshpande

Bitcoin has created a new exchange paradigm within which financial transactions can be trusted without an intermediary. This premise of a free decentralized transactional network however requires, in its current implementation, unrestricted access to the ledger for peer-based transaction verification. A number of studies have shown that, in this pseudonymous context, identities can be leaked based on transaction features or off-network information. In this work, we analyze the information revealed by the pattern of transactions in the neighborhood of a given entity transaction. By definition, these features which pertain to an extended network are not directly controllable by the entity, but might enable leakage of information about transacting entities. We define a number of new features relevant to entity characterization on the Bitcoin Blockchain and study their efficacy in practice. We show that even a weak attacker with shallow data mining knowledge is able to leverage these features to characterize the entity properties.

Mark Huasong Meng, Yaou Qian

Blockchain is a game changer in nowadays information technology and financial industry. Since Nakamoto invented the concept of blockchain together with its first application called “Bitcoin”, the topic of blockchain has been inundated with the booming of cryptocurrencies. People expect this novel distributed ledger technology to bring a revolution to the entire industry and thereby grab the opportunity to expand and strengthen their business. The supply chain is treated as a typical use case to adopt blockchain and relevant technologies in many previous studies. In this paper, we conduct an interdisciplinary study on business supply chain management and the latest distributed ledger technology. In accordance with our discussion and experiments, we list three major benefits that the adoption of blockchain is able to bring to contemporary supply chain management. Meanwhile, we also identify a few of challenges that the nowadays blockchain application could not effectively excel, and the potential mitigation to those challenges as well.

Jinwook Lee, Paul Moon Sub Choi

Since the inception of blockchain and Bitcoin (Nakamoto (2008)), a decentralized-distributed ledger system and its associated cryptocurrency, respectively, the world has witnessed a slew of newer adaptations and applications. Although the original distributed ledger technology (DLT) of blockchain is deemed secure and decentralized, the confirmation of transactions is inefficient by design. Recently adopted, directed acyclic graph (DAG)-based distributed ledgers validate transactions efficiently without the physically and environmentally costly building process of blocks (Lerner (2015)). However, centrally-controlled confirmation against the odds of multiple validation disqualifies the DAG as a decentralized-distributed ledger. In this regard, we introduce an innovative DLT by reconstructing a chain of antichains based on a given DAG-pool of transactions. Each antichain (box) contains distinct nodes whose approved transactions are recursively validated by subsequently augmenting nodes. The boxer node closes the box and keeps the hash of all transactions confirmed by the box-genesis node. Designation of boxers and box-geneses is conditionally randomized for decentralization. The boxes are serially concatenated with recursive confirmation (boxchain) without incurring the cost of box generation. Rewards (boxcoin) are paid to the contributing nodes of the ecosystem whose trust is built on the doubly-secure protocol of confirmation. A value-preserving medium of payment (boxdollar) is among numerous practical applications discussed herein.

Yong Yu, Yujie Ding, Yanqi Zhao, Yannan Li · 7 authors

Currently, the number of Internet of Thing (IoT) devices making up the IoT is more than 11 billion and this number has been continuously increasing. The prevalence of these devices leads to an emerging IoT business model called Device-as-a-service(DaaS), which enables sensor devices to collect data disseminated to all interested devices. The devices sharing data with other devices could receive some financial reward such as Bitcoin. However, side-channel attacks, which aim to exploit some information leaked from the IoT devices during data trade execution, are possible since most of the IoT devices are vulnerable to be hacked or compromised. Thus, it is challenging to securely realize data trading in IoT environment due to the information leakage such as leaking the private key for signing a Bitcoin transaction in Bitcoin system. In this paper, we propose LRCoin, a kind of leakage-resilient cryptocurrency based on bitcoin in which the signature algorithm used for authenticating bitcoin transactions is leakage-resilient. LRCoin is suitable for the scenarios where information leakage is inevitable such as IoT applications. Our core contribution is proposing an efficient bilinear-based continual-leakage-resilient ECDSA signature. We prove the proposed signature algorithm is unforgeable against adaptively chosen messages attack in the generic bilinear group model under the continual leakage setting. Both the theoretical analysis and the implementation demonstrate the practicability of the proposed scheme.

Antônio Unias de Lucena, Marco Aurélio Amaral Henriques

Um computador quântico com alta capacidade de processamento quebrará as assinaturas digitais utilizadas nos principais blockchains. Este trabalho traz um estudo preliminar sobre a adoção de assinaturas baseadas em hash no blockchain do Bitcoin para torná-lo resistente ao computador quântico. O estudo mostra os pontos a serem modificados e seus impactos. O maior deles refere-se ao tamanho da assinatura digital, que influencia no tamanho de uma transação e diminui o número de transações por bloco. Soluções para este problema incluem o aumento do tamanho do bloco, a diminuição do tamanho das assinaturas baseadas em hash e/ou a adoção de algoritmos pós-quânticos que produzam assinaturas digitais menores.

Hiroki Watanabe, Shigenori Ohashi, Shigeru Fujimura, Atsushi Nakadaira · 6 authors

Bitcoin's enormous success has inspired the development of alternative blockchains, such as consortium chains. Several cross-chain protocols have been proposed as ways of connecting these universes of individual blockchains in a distributed and secure manner. In this paper, we present Niji, a new cross-chain protocol that allows parties to perform virtual Bitcoin payment securely on a consortium chain, without any trusted third-party or mediators. Our work focuses on the issue that it is difficult for a consortium chain's token to hold a stable market value, and Niji makes it possible for smart contract services to acquire means of payment in the consortium chain. With the Bitcoin payment channel built on the consortium chain, the process from payment to service provision runs autonomously without any interaction between parties. Niji introduces the concept of a transaction template to validate Bitcoin payments efficiently on different blockchains, and it allows a service provider to delegate all of its tasks for verifying state updates to a smart contract on the consortium chain. We also propose a novel bi-directional payment channel adapted for design of the Niji protocol, which can update payments non-interactively between parties. We implemented a prototype of the Niji protocol and conducted an experiment measuring the computational cost and latency that demonstrates the protocol's feasibility on practical platforms.

Nader Trabelsi

In the present paper, we investigate connectedness within cryptocurrency markets as well as across the Bitcoin index (hereafter, BPI) and widely traded asset classes such as traditional currencies, stock market indices and commodities, such as gold and Brent oil. A spill over index approach with the spectral representation of variance decomposition networks, is employed to measure connectedness. Results show no significant spillover effects between the nascent market of cryptocurrencies and other financial markets. We suggest that cryptocurrencies are real independent financial instruments that pose no danger to financial system stability. Concerning the connectedness within the cryptocurrency markets, we report a time–frequency–dynamics connectedness nature. Moreover, the decomposition of the total spill over index is mostly dominated by a short frequency component (2–4 days) leading to the conclusion that this nascent market is highly speculative at present. These findings provide insights for regulators and potential international investors.

Pierre Reibel, Haaroon Yousaf, Sarah Meiklejohn

Interest in cryptocurrencies has skyrocketed since their introduction a decade ago, with hundreds of billions of dollars now invested across a landscape of thousands of different cryptocurrencies. While there is significant diversity, there is also a significant number of scams as people seek to exploit the current popularity. In this paper, we seek to identify the extent of innovation in the cryptocurrency landscape using the open-source repositories associated with each one. Among other findings, we observe that while many cryptocurrencies are largely unchanged copies of Bitcoin, the use of Ethereum as a platform has enabled the deployment of cryptocurrencies with more diverse functionalities.

Mr.Kandy Arora, Mr.Ashish Verma, Mr.Aarush Sharma, Prof.Neelu

<em>The research paper deals</em><em> with Bitcoin ,its mining and how mining actually works how Bitcoins are made, uses of Bitcoin why we should use Bitco in. Digital wallets for storing Bitcoins It also covers some of the biggest issues associated with Bitcoin like adecentralized currency covering the vast problem of Doublespending ininitial days of Bitcoin trading.The uses of Block-chain in Bit coin’stransaction to solve the problem of Double spending of Bitcoin.Applications of Block-chain other than crypto currency like in healthcare sector,reale state, voting, cyber security,it also covers sections by which we can make block-chain faster especially while buying crypto currencies and why SSDs should be preferred for Bloch-chain operations.</em>

Amitha Raghava-Raju

Bitcoin is an established cryptographic digital currency whose value lays in the computational complexity rather than a physical commodity. Bitcoin is an open source software program with three aspects. (i) Peer-to-Peer networklow barrier entry; (ii) Mininginevitable concentration of power; (iii) Software upgrades. The nodes on the network follow a decentralized consensus for establishing the value of ledger and updating the blockchain which serves as a single source of truth for all transactions. As cryptocurrencies are developing more compelling utilities, creating ever faster and safer payment systems they are shifting the "money paradigm". Bitcoins are an evolution in money and provide a unique opportunity to forecast their price unlike the existing fiat currencies. The goal of this paper is to implement, train and evaluate several machine learning models in order to predict the price of the most popular cryptocurrency -Bitcoins. The various machine learning algorithms employed are -Linear Regression, K-Nearest Neighbors, Ridge Regression, Lasso Regression,

Karan Ganju, Qi Wang, Wei Yang, Carl A. Gunter · 5 authors

With the growing adoption of machine learning, sharing of learned models is becoming popular. However, in addition to the prediction properties the model producer aims to share, there is also a risk that the model consumer can infer other properties of the training data the model producer did not intend to share. In this paper, we focus on the inference of global properties of the training data, such as the environment in which the data was produced, or the fraction of the data that comes from a certain class, as applied to white-box Fully Connected Neural Networks (FCNNs). Because of their complexity and inscrutability, FCNNs have a particularly high risk of leaking unexpected information about their training sets; at the same time, this complexity makes extracting this information challenging. We develop techniques that reduce this complexity by noting that FCNNs are invariant under permutation of nodes in each layer. We develop our techniques using representations that capture this invariance and simplify the information extraction task. We evaluate our techniques on several synthetic and standard benchmark datasets and show that they are very effective at inferring various data properties. We also perform two case studies to demonstrate the impact of our attack. In the first case study we show that a classifier that recognizes smiling faces also leaks information about the relative attractiveness of the individuals in its training set. In the second case study we show that a classifier that recognizes Bitcoin mining from performance counters also leaks information about whether the classifier was trained on logs from machines that were patched for the Meltdown and Spectre attacks.

Frode Kjærland, Aras Khazal, Erlend Aune Krogstad, Frans B. Gyllenhammar Nordstrøm · 5 authors

This paper aims to enhance the understanding of which factors affect the price development of Bitcoin in order for investors to make sound investment decisions. Previous literature has covered only a small extent of the highly volatile period during the last months of 2017 and the beginning of 2018. To examine the potential price drivers, we use the Autoregressive Distributed Lag and Generalized Autoregressive Conditional Heteroscedasticity approach. Our study identifies the technological factor Hashrate as irrelevant for modeling Bitcoin price dynamics. This irrelevance is due to the underlying code that makes the supply of Bitcoins deterministic, and it stands in contrast to previous literature that has included Hashrate as a crucial independent variable. Moreover, the empirical findings indicate that the price of Bitcoin is affected by returns on the S&amp;P 500 and Google searches, showing consistency with results from previous literature. In contrast to previous literature, we find the CBOE volatility index (VIX), oil, gold, and Bitcoin transaction volume to be insignificant.

Yuan Wu, Xiangxu Chen, Jiajun Shi, Kejie Ni · 7 authors

Blockchain has emerged as a decentralized and trustable ledger for recording and storing digital transactions. The mining process of Blockchain, however, incurs a heavy computational workload for miners to solve the proof-of-work puzzle (i.e., a series of the hashing computation), which is prohibitive from the perspective of the mobile terminals (MTs). The advanced multi-access mobile edge computing (MEC), which enables the MTs to offload part of the computational workloads (for solving the proof-of-work) to the nearby edge-servers (ESs), provides a promising approach to address this issue. By offloading the computational workloads via multi-access MEC, the MTs can effectively increase their successful probabilities when participating in the mining game and gain the consequent reward (i.e., winning the bitcoin). However, as a compensation to the ESs which provide the computational resources to the MTs, the MTs need to pay the ESs for the corresponding resource-acquisition costs. Thus, to investigate the trade-off between obtaining the computational resources from the ESs (for solving the proof-of-work) and paying for the consequent cost, we formulate an optimization problem in which the MTs determine their acquired computational resources from different ESs, with the objective of maximizing the MTs' social net-reward in the mining process while keeping the fairness among the MTs. In spite of the non-convexity of the formulated problem, we exploit its layered structure and propose efficient distributed algorithms for the MTs to individually determine their optimal computational resources acquired from different ESs. Numerical results are provided to validate the effectiveness of our proposed algorithms and the performance of our proposed multi-access MEC for Blockchain.

Aisha Fouad Bushager, Z. Mirza, E Alsalem

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Christian Badertscher, Peter Gaži, Aggelos Kiayias, Alexander Russell · 5 authors

We present a novel Proof-of-Stake (PoS) protocol, Ouroboros Genesis, that enables parties to safely join (or rejoin) the protocol execution using only the genesis block information. Prior to our work, PoS protocols either required parties to obtain a trusted "checkpoint" block upon joining and, furthermore, to be frequently online or required an accurate estimate of the number of online parties to be hardcoded into the protocol logic. This ability of new parties to "bootstrap from genesis" was a hallmark property of the Bitcoin blockchain and was considered an important advantage of PoW-based blockchains over PoS-based blockchains since it facilitates robust operation in a setting with dynamic availability, i.e., the natural setting---without external trusted objects such as checkpoint blocks---where parties come and go arbitrarily, may join at any moment, or remain offline for prolonged periods of time. We prove the security of Ouroboros Genesis against a fully adaptive adversary controlling less than half of the total stake in a partially synchronous network with unknown message delay and unknown, varying levels of party availability. Our security proof is in the Universally Composable setting assuming the most natural abstraction of a hash function, known as the strict Global Random Oracle (ACM-CCS 2014); this highlights an important advantage of PoS blockchains over their PoW counterparts in terms of composability with respect to the hash function formalisation: rather than a strict GRO, PoW-based protocol security requires a "local" random oracle. Finally, proving the security of our construction against an adaptive adversary requires a novel martingale technique that may be of independent interest in the analysis of blockchain protocols.

Pedro Chaim, Márcio Poletti Laurini

No abstract is available for this record.