Andrew Miller, Iddo Bentov, Surya Bakshi, Ranjit Kumaresan · 5 authors
Bitcoin, Ethereum and other blockchain-based cryptocurrencies, as deployed today, cannot scale for wide-spread use. A leading approach for cryptocurrency scaling is a smart contract mechanism called a payment channel which enables two mutually distrustful parties to transact efficiently (and only requires a single transaction in the blockchain to set-up). Payment channels can be linked together to form a payment network, such that payments between any two parties can (usually) be routed through the network along a path that connects them. Crucially, both parties can transact without trusting hops along the route. In this paper, we propose a novel variant of payment channels, called Sprites, that reduces the worst-case "collateral cost" that each hop along the route may incur. The benefits of Sprites are two-fold. 1) In Lightning Network, a payment across a path of $\ell$ channels requires locking up collateral for $Θ(\ellΔ)$ time, where $Δ$ is the time to commit an on-chain transaction. Sprites reduces this cost to $O(\ell + Δ)$. 2) Unlike prior work, Sprites supports partial withdrawals and deposits, during which the channel can continue to operate without interruption. In evaluating Sprites we make several additional contributions. First, our simulation-based security model is the first formalism to model timing guarantees in payment channels. Our construction is also modular, making use of a generic abstraction from folklore, called the "state channel," which we are the first to formalize. We also provide a simulation framework for payment network protocols, which we use to confirm that the Sprites construction mitigates against throughput-reducing attacks.
Andrew Miller, Iddo Bentov, Ranjit Kumaresan, Christopher Cordi · 5 authors
Bitcoin, Ethereum and other blockchain-based cryptocurrencies, as deployed\ntoday, cannot scale for wide-spread use. A leading approach for cryptocurrency\nscaling is a smart contract mechanism called a payment channel which enables\ntwo mutually distrustful parties to transact efficiently (and only requires a\nsingle transaction in the blockchain to set-up). Payment channels can be linked\ntogether to form a payment network, such that payments between any two parties\ncan (usually) be routed through the network along a path that connects them.\nCrucially, both parties can transact without trusting hops along the route.\n In this paper, we propose a novel variant of payment channels, called\nSprites, that reduces the worst-case "collateral cost" that each hop along the\nroute may incur. The benefits of Sprites are two-fold. 1) In Lightning Network,\na payment across a path of $\\ell$ channels requires locking up collateral for\n$\\Theta(\\ell\\Delta)$ time, where $\\Delta$ is the time to commit an on-chain\ntransaction. Sprites reduces this cost to $O(\\ell + \\Delta)$. 2) Unlike prior\nwork, Sprites supports partial withdrawals and deposits, during which the\nchannel can continue to operate without interruption.\n In evaluating Sprites we make several additional contributions. First, our\nsimulation-based security model is the first formalism to model timing\nguarantees in payment channels. Our construction is also modular, making use of\na generic abstraction from folklore, called the "state channel," which we are\nthe first to formalize. We also provide a simulation framework for payment\nnetwork protocols, which we use to confirm that the Sprites construction\nmitigates against throughput-reducing attacks.\n
Thomas Dickerson, Paul Gazzillo, Maurice Herlihy, Eric Koskinen
Modern cryptocurrency systems, such as Ethereum, permit complex financial transactions through scripts called smart contracts. These smart contracts are executed many, many times, always without real concurrency. First, all smart contracts are serially executed by miners before appending them to the blockchain. Later, those contracts are serially re-executed by validators to verify that the smart contracts were executed correctly by miners. Serial execution limits system throughput and fails to exploit today's concurrent multicore and cluster architectures. Nevertheless, serial execution appears to be required: contracts share state, and contract programming languages have a serial semantics. This paper presents a novel way to permit miners and validators to execute smart contracts in parallel, based on techniques adapted from software transactional memory. Miners execute smart contracts speculatively in parallel, allowing non-conflicting contracts to proceed concurrently, and "discovering" a serializable concurrent schedule for a block's transactions, This schedule is captured and encoded as a deterministic fork-join program used by validators to re-execute the miner's parallel schedule deterministically but concurrently. Smart contract benchmarks run on a JVM with ScalaSTM show that a speedup of of 1.33x can be obtained for miners and 1.69x for validators with just three concurrent threads.
Smart contracts are full-fledged programs that run on blockchains (e.g., Ethereum, one of the most popular blockchains). In Ethereum, gas (in Ether, a cryptographic currency like Bitcoin) is the execution fee compensating the computing resources of miners for running smart contracts. However, we find that under-optimized smart contracts cost more gas than necessary, and therefore the creators or users will be overcharged. In this work, we conduct the first investigation on Solidity, the recommended compiler, and reveal that it fails to optimize gas-costly programming patterns. In particular, we identify 7 gas-costly patterns and group them to 2 categories. Then, we propose and develop GASPER, a new tool for automatically locating gas-costly patterns by analyzing smart contracts' bytecodes. The preliminary results on discovering 3 representative patterns from 4,240 real smart contracts show that 93.5%, 90.1% and 80% contracts suffer from these 3 patterns, respectively.
In the US, the services sector provides employment to about 100 million, while the manufacturing sector provides employment to about 20 million. These sectors are highly automated, and driven by sophisticated business processes forming an integral part of the digital economy. While the applications themselves may be distributed over the Internet in time and space, the core business, regulatory, and financial aspects of the digital economy are still centralized, with the need for centralized agencies (such as banks, customs authorities, and tax agencies) to authenticate and settle payments and transactions. These centralized services often are manual, difficult to automate, and represent a bottleneck to facilitating a frictionless digital economy. The next revolutionary step in the services and manufacturing economy of the future is the development of automated distributed applications that do not depend on these traditional centralized agencies for controlling, facilitating and settling multi-party transactions that may themselves be subject to complex contractual constraints. The blockchain technology is an integral part of these next steps that promises a smart new world of automation of complex services and manufacturing processes. Blockchain is a distributed and public ledger which maintains records of all the transactions on a blockchain network comprising suppliers of products and services and consumers. With the blockchain's ability to establish trust in a peer-to-peer network through a distributed consensus mechanism rather than relying on a powerful centralized authority, the technology is being seen by the industry experts as one of the greatest innovations since the invention of the Internet. As per Santander, blockchain technologies can reduce annual costs for financial firms by $20b by streamlining processes and improving efficiency. In addition, investment and spending on blockchain technology is expected to increase at a compound annual growth rate (CAGR) of 52% through 2019. We have written this textbook, as part of our expanding Hands-On Approach(TM) series, to serve as a textbook for senior-level and graduate-level courses on financial and regulation technologies, business analytics, Internet of Things, and cryptocurrency. This book is also written for use within industries in the FinTech and RegTech space that may be interested in rolling out products and services that utilize this new area of technology. An accompanying website for this book contains additional support for instruction and learning (www.blockchain-book.com). The book is organized into three main parts, comprising a total of ten chapters. Part I provides an introduction to blockchain concepts, design patterns, and architectures for blockchain applications. A blockchain stack comprising a decentralized computation platform, a decentralized messaging platform, and a decentralized storage platform is described. Part II introduces the readers to tools and platforms for blockchain, such as Geth, PyEthApp, TestRPC, Mist Ethereum Wallet, MetaMask, Web3 JavaScript API and the Truffle Dapp framework. Implementation examples of various smart contracts and decentralized applications (Dapps) are provided. Part III focuses on advanced topics such as the security and scalability related challenges for the blockchain platforms.
Ethereum contracts can be designed to function as fully decentralized applications called DAPPs. Many DAPPs have already been fielded, including an online marketplace, a role playing game, a prediction market, and an Internet service provider. Unfortunately, DAPPs can be hacked, and the assets they control can be stolen. A recent attack on an Ethereum decentralized application called The DAO demonstrated that smart contract bugs are more than an academic concern. Ether worth tens of millions of US dollars was extracted by an attacker from The DAO, sending the value of its tokens and the overall exchange price of ether tumbling. We present a market-based technique for insuring the ether holdings of a DAPP using futures contracts indexed by the trade price of ether for DAPP tokens. Under fairly general circumstances, our technique is capable of recovering the majority of ether lost from theft with high probability even when all of the ether holdings are stolen; and the only cost to DAPP token holders is an adjustable ether withdrawal fee. If the probability of a margin call in $d$ days is $p$ for a futures contract with 20 times leverage, then our approach will allow for the recovery of half the stolen ether with probability $p$ and a withdrawal fee of 5%. A higher withdrawal fee of 25% allows for more than 80% of the ether to be recovered with probability $p$.
A book introducing Ethereum and Solidity would not be complete without mention of the nascent cult of personality forming around Vitalik Buterin, the inventor of Ethereum and a collaborator on a handful of other high-profile blockchain projects. These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
Bryan Abdón Mendoza Muñoz, Kelly Muñoz, Dasha Villasis
Extensive research is carried out on the two most important cryptocurrencies at world level, the Ether (Ethereum) and the Bitcoin with the passage of time has been positioned in this medium, this due to the great consensus that had the Ethereum in the course of the last three years
The main focus of this article is the analysis of the global cryptocurrency market as an integrated system of cryptocurrencies and infrastructures that ensure their functioning. In particular, the general state of the cryptocurrency market and its current trends have been considered. The main part of the analysis was conducted on the structure of the global cryptocurrency market and its main components. Based on the indicator of cryptocurrency market capitalization, leading cryptocurrencies have been defined. They currently represent 80% of the world cryptocurrency market. These include Bitcoin, Ethereum, Ripple, Bitcoin Cash, Cardano, Litecoin and NEM. Key players in the cryptocurrency market infrastructure have been also determined, they support and contribute to the development of the market of almost every cryptocurrency. These include miners, full nodes, exchanges, wallets and payment companies. The main market indicators for each leading cryptocurrencies such as: the market share and its change over the year, the degree of influence of the cryptocurrency on the state of the global market, the dynamics of prices and their volatility have been analyzed. The infrastructure of the market of each cryptocurrency has been estimated on the basis of indicators of the reliability of the infrastructure and its trade opportunities. The study showed a high growth rate of Bitcoin and along with it a number of significant altcoins over the past year, which had a favorable effect on the state of the common cryptocurrency market. Almost every cryptocurrency showed positive trends. Ripple is the absolute record holder of price growth over the past year, followed by NEM. Bitcoin and Ethereum are the least financially risky ones in terms of volatility. In addition, Ethereum has the most reliable infrastructure, and Bitcoin has the most secured by exchanges and wallets. Cardano showed the highest growth rates in a short period of time. In general, these phenomena are positive forerunners for the cryptocurrency industry.
All human interaction can be depicted as exchanges. We exchange trivial information, feelings, assets and more. Valuable exchanges have one thing in common; they all require some degree of trust. In today’s society we rely on institutionalized trust when commencing an exchange of value. Typically, this role is filled by a vast ecosystem consisting of commercial banks, clearinghouses and other third parties. The recent rise of Bitcoin, Ethereum and consequent attention on the underlying technology, blockchain, questions the future of current ecosystem. This report aims at uncovering what blockchain is, what different implementations are currently available and how it would affect today’s ecosystem. It does so through semistructured interviews with actors within the current ecosystem as well as weighing in the views of blockchain evangelists. It highlights five key aspects that are crucial when implementing blockchain technology within the existing banking paradigm. Today’s organized societies require law and order which, to a large extent, is limited within the realm of public blockchain technology. With the insight of society’s infrastructural limitations, this paper argue that the current transaction system of our society favors a permissioned implementation with trusted nodes. Such a system would result in more efficient financial markets and lower costs of transacting. However, this paper acknowledge the virtues and reasons behind the rise of public blockchains. Given recent developments within the field and interesting concepts, the report does not dare to exclude a future of banking relying on public blockchain technology as the underlying database.
Jean-Marc Seigneur, Hélie D'hautefort, G. Ballocchi
The number of crypto-currencies is increasing fast. On one hand, following the launch of Bitcoin in 2009, more than 1000 different crypto-currencies are listed in the crypto-currency markets. On the other hand, solutions like eCurrency exist to effectively create digital fiat currencies. There are solid economic reasons to introduce an optimized basket of fiat currencies as well, along the lines of the International Monetary Fund Special Drawing Rights, particularly for entities with global assets and liabilities or for individuals wishing to protect their purchasing power in a more and more global and multipolar world. Up to now this kind of solution was only accessible to a few large institutions due to the structure of the foreign exchange market. The main original contribution of this paper is to present the first use case of linking a managed basket of fiat currencies to a new crypto-token. The tokenisation and the use of blockchain will enable us to make it accessible to any individual gaining diversification while benefiting from good liquidity and low cost. After reviewing recent digital fiat currencies initiatives, we explain the economic rationale of our optimized currency basket and its effective implementation by means of an existing blockchain-based distributed computing platform, i.e., Ethereum. Our technological approach enables a wide range of uses of our currency basket, which would not be possible without crypto-tokens.
The digital art landscape has rapidly expanded since the passing of Visual Rights Act of 1990 (Baron, 1996; CAA, 2013). With the recent advent of blockchain technologies, derived from Nakamoto’s Bitcoin currency, new possibilities have emerged for the way artistic materials can be exchanged and how communications can be conducted. This research examines emerging applications for decentralized blockchain technologies in community-based art projects and digital art startups¬. The work of three organizations, ConsenSys, Ethereum, and Monegraph, is explored. Through the use of blockchain technologies, digital artists can create a traceable and tradable record of their work, while generating a critical discourse around the reproducibility of media. In this research, I investigate the potential uses of digital art in the blockchain and its educational value in visual arts education.
Mining is important as the process by which consensus is reached in the system, and by which ether is created. Bitcoin also uses mining to reach consensus, but the way things work in Ethereum is a little bit different, owing to its ability to execute smart contracts. These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
We review seminal social science theories of Trust & Control to consider how their application to Blockchain and Cryptocurrency (DLT, e.g., Bitcoin, Ethereum, Ripple) provide the potential for fresh criminal and information security challenges to traditional mechanisms of criminal detection and law enforcement. The social science theories of trust and control provide an accessible matrix to evaluate malicious behavior related to these new forms of money and currency. This foreshadows the ability for DLTs to become the âpoison of choiceâ for crime and security objectives or perhaps be avoided altogether by criminals. We argue that an understanding of DLTs is incomplete without a social science underpinning and framework which trust and control provide. The continued use of these technologies will require public and private institutions to rethink their approaches to crime prevention and information security for purely digital threats.
In less than a calendar year, initial coin offerings or “ICOs” have become the fastest growing capital market in the world. In 2016, an entity called The DAO raised $160 million by selling crypto-tokens to over 15,000 individual purchasers around the globe. This massive fund raise would give rise to an entirely new capital ecosystem. In 2017, initial coin offerings would explode, raising a collective $3.5 billion in just the first three quarters of the year. All of this was done without a single registration being filed with the SEC, and many of these initial coin offerings — including several $100 million raises — were based on little more than a white paper and few lines of sample code. Welcome to the new Digital Wild West. With the seemingly overnight success of this new funding mechanism, there is little if any legal scholarship addressing initial coin offerings and how, or if, such offerings should be regulated. This article provides a non-technical legal audience with a foundational understanding of how the blockchain works, and the role initial coin offerings play in this new economic ecosystem. The overarching thesis of the article is that our current securities law framework, a framework that dates to the days of the great depression, is ill-equipped to handle this new world of decentralized, global, pseudonymous fund raises on public blockchains. Instead, governmental regulators should be working with core development teams to build a regulatory framework that integrates investor protections directly into the computer code governing these systems. By embracing “code as law,” both regulators and core development teams can protect the innovation being funded by initial coin offerings, while at the same time injecting some much needed investor protections into this new ecosystem. This article begins with an introduction to the coming decentralized world, including an overview of both public blockchain technology as well the Ethereum platform, the primary public blockchain upon which initial coin offerings are being deployed. Central to this introduction is an explanation of how the decentralization and disintermediation brought by the blockchain has the potential to dramatically reshape our economic and social systems. Next, the article explores the recent explosion of initial coin offerings, discussing how these offerings are structured, and how this new funding mechanism, if developed properly, has the promise of democratizing opportunities for economic innovation. The article then examines the SEC’s early statements on initial coin offerings to illustrate the potential problems with applying a dated legal framework to this new technology. Finally, the article concludes that the traditional securities law framework is ill suited for the coming decentralized world because the SEC’s enforcement power over global blockchain platforms is limited. Recognizing that external legal frameworks cannot be forced upon public blockchain platforms, the article argues for a collaborative process where governmental regulators work with core development teams to build a regulatory framework into the very fabric of these platforms, thereby providing investors protection, while at the same time embracing the concept of code as law.
Let’s take a break from mining and deployment and talk about some of the design choices that went into Ethereum: specifically, those around its system of economic incentives and disincentives. These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
Roman Beck, Christian Becker, Juho Lindman, Matti Rossi
This report documents the program and the outcomes of Dagstuhl Seminar 17132 "Opportunities and Risks of Blockchain Technologies". Blockchain-based applications such as Bitcoin or Ethereum are emerging technologies, but a dramatic increase in industrial and academic interest in the technology is evident. Start-ups and large financial players are working intensely on blockchain-based applications, making this one of the most promising drivers of financial innovation. However, the design and implementation of blockchain-based systems requires deep technical know-how in various areas, as well as consideration of economic and societal issues. These opportunities and challenges provided the starting point for the Dagstuhl Seminar where we analyzed and synthesized the current body of knowledge on the emerging landscape of blockchain technologies. We linked cryptographic economic systems to already established research streams around trust-related issues in payment systems and digital currencies, and digital asset management.
Dapps are composed of smart contracts that, as noted at several junctures in this book, are executed by all nodes on the Ethereum network at approximately the same time. These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
The purpose of this study was to describe social movement meeting organization and to increase the understanding of organized spaces for collective action. This paper contributes to several research streams. Firstly, this study advances a novel research stream conceptualizing social movements as spaces, and particularly as open rather than isolated spaces. Secondly, it raises meetings into the focal point of organizing and offers a multisided examination of meeting organization instead of limiting structure under one label such as network or formal organization. Thirdly, by focusing on organizing based on multiple logics and partial organization this study brings forward the understanding of organizing in the contemporary society as well as organization located in the outskirts of formal organizations. Fourthly, by making a distinction between organizing and mobilizing, this study develops the understanding of how movements can serve as a resource for individual actors and their goals. Finally, the case provides a rare example of a movement born around a nascent digital innovation with possibly considerable impact on society. The research was carried out as a descriptive case study focusing on the meetings of Helsinki Ethereum Meetup, which is a meeting-based organization set up around a nascent blockchain platform, Ethereum. The primary data consisted of eight interviews with the meetup participants. In addition, the case was complemented by an analysis of the group’s social media accounts and membership data retrieved from meetup.com, through which the group was facilitated. The data was analyzed utilizing a dual approach deploying both open coding and theory-based coding techniques. Meetings and their organization were analyzed from three perspectives: a network, an institution and an organization. Furthermore, the case analysis included identifying the ideological, business and political context of the case and the meetup group’s relations to other groups in the field of blockchain technologies. The results of the analysis indicate that the meetings can be described as a hybrid of a norm-based institution, a network hub and a partial organization with less than all elements of a formal organization. In practice, all three perspectives are linked to each other and together complement each other to form one entity. However, this study implies that the specific logics can be regarded as analytically separate to arrive at a more pronounced multilevel analysis of meeting organizing. In addition, the case organization was found to be an example of a pioneer group in its own field being the first and only meetup devoted to Ethereum in Finland at the time of the study. Furthermore, the settings and the organization of the meetup were possibly linked to the group’s position in its field and the nascent developmental state of Ethereum.