Follow blockchain research across journals, conferences, and preprint repositories.
1,455 results · page 57 of 61
Hemang Subramanian
In a decentralized marketplace, buyers and sellers transact directly, without manipulation by intermediary platforms.
Robin P. G. Tech, Konstanze Neumann, Wendelin Michel
No abstract is available for this record.
Nguyen Cong Luong, Zehui Xiong, Ping Wang, Dusit Niyato
Blockchain has recently been applied in many applications such as bitcoin, smart grid, and Internet of Things (IoT) as a public ledger of transactions. However, the use of blockchain in mobile environments is still limited because the mining process consumes too much computing and energy resources on mobile devices. Edge computing offered by the Edge Computing Service Provider can be adopted as a viable solution for offloading the mining tasks from the mobile devices, i.e., miners, in the mobile blockchain environment. However, a mechanism needs to be designed for edge resource allocation to maximize the revenue for the Edge Computing Service Provider and to ensure incentive compatibility and individual rationality is still open. In this paper, we develop an optimal auction based on deep learning for the edge resource allocation. Specifically, we construct a multi-layer neural network architecture based on an analytical solution of the optimal auction. The neural networks first perform monotone transformations of the miners' bids. Then, they calculate allocation and conditional payment rules for the miners. We use valuations of the miners as the data training to adjust parameters of the neural networks so as to optimize the loss function which is the expected, negated revenue of the Edge Computing Service Provider. We show the experimental results to confirm the benefits of using the deep learning for deriving the optimal auction for mobile blockchain with high revenue
Xueqin Liang, Zheng Yan
A number of information and resource sharing systems arise and become popular with the rapid development of communication technologies and mobile smart devices. The interactions between humans and machines are intense and their synergistic reactions have attracted special attention for the reason of forming so called Human–Machine Networks (HMN). HMNs refer to these networks where humans and machines work together to provide synergistic effects on their payoffs. Game theory, which can capture the interactions among players dexterously, has been widely used in solving various problems in HMN systems from the view of economics. In this paper, we extensively review the literature about game theoretical methods in HMNs, in particular focusing on its typical systems such as crowdsourcing, an elemental HMN and Internet of Things (IoT), a hybrid HMN, as well as Bitcoin. We propose a series of requirements to evaluate existing work. For reviewing and analyzing each system, we specify application purposes, players, strategies, game models and equilibria based on our proposed requirements. In the sequel, we identify a number of common and distinct open issues in HMNs and point out future research directions.
Jussi Hukkinen, Juri Mattila, Timo Seppälä
This report documents a blockchain application developed for the real estate sector. The application enables distributed workflow management in a complicated transaction process: the selling of a share of stocks in a housing corporation. As its core element, the application utilizes Ethereum-based smart contracts to facilitate the interaction of various parties involved, as well as the Interplanetary File System (IPFS) to combine data from a number of separate information pools. The motive for this application has been to understand the process of developing blockchain applications with industrial partners. Moreover, the purpose of this exercise has been to examine whether Ethereum-based smart contracts could be effectively utilized for applications in industry and finance. The application and the discussions during its development indicate that similar, market-driven workflow structures may appear in value chains where the number of parties is high and where the sources of information are numerous yet disconnected.
Benedikt Notheisen, Jacob B. Cholewa, Arun Prasad Shanmugam
No abstract is available for this record.
Ron Lavi, Or Sattath, Aviv Zohar
The Bitcoin payment system involves two agent types: Users that transact with the currency and pay fees and miners in charge of authorizing transactions and securing the system in return for these fees. Two of Bitcoin's challenges are (i) securing sufficient miner revenues as block rewards decrease, and (ii) alleviating the throughput limitation due to a small maximal block size cap. These issues are strongly related as increasing the maximal block size may decrease revenue due to Bitcoin's pay-your-bid approach. To decouple them, we analyze the “monopolistic auction” [8], showing: (i) its revenue does not decrease as the maximal block size increases, (ii) it is resilient to an untrusted auctioneer (the miner), and (iii) simplicity for transaction issuers (bidders), as the average gain from strategic bid shading (relative to bidding one's true maximal willingness to pay) diminishes as the number of bids increases.
David Burth Kurka, Jeremy Pitt
The increasing automation and capacity of communication of industrial systems brings new possibilities and challenges to the sector. We investigate a problem of distributed and collective supply and discuss solutions to the issue of fair and reliable decision making in open systems. By combining principles of social organisation with blockchain and smart-contract technologies, we show that it is possible to develop a system for common-pool resource management able to take quick decisions on an industrial scale, while ensuring cooperation and self-organising strategies that encourage compliance. Our results demonstrate that our model -- the Smart-CPR - is able to distribute resources efficiently and is capable of detecting and punishing non-compliant or unhelpful behaviour.
Voshmgir Shermin
Abstract Blockchain as an engine for auto‐enforceable smart contracts could disrupt traditional governance structures by reducing bureaucracy through lower transaction costs, solving principal–agent issues, and subsequent moral hazard. While machine consensus can radically reduce transaction costs and disrupt traditional governance structures, there is a gap between initial conceptualizations of blockchains and their first instantiations. First use cases show that as circumstances change, protocols can become inappropriate for the new environment and require modification. Modification of blockchain code happens through majority consensus, but reaching consensus in a distributed multi‐stakeholder network with sometimes unaligned interests is complex, potentially introducing new agency issues.
Joshua G. Coyne, Peter L. McMickle
ABSTRACT The blockchain has enabled the successful creation of decentralized digital currency networks. This success has prompted further investigation into the usefulness of blockchains in other business settings. Because of the blockchain's use as a ledger, the question arises whether the blockchain could become a more secure alternative to current accounting ledgers. We show that this is infeasible. By casting this question in the context of the Byzantine Generals Problem, which the blockchain was designed to solve, we identify multiple flaws hindering implementation of the blockchain as a financial reporting tool. Whereas blockchain-based digital currencies only exist within the blockchain, economic transactions exist outside of accounting records. This distinction prevents an acceptable level of transaction verification using the blockchain model. Additionally, the security benefits of the blockchain that render it ostensibly immutable are not fully available or reliable in an accounting setting.
Juan Beccuti, Christian Jaag
We consider a game in which Bitcoin miners compete for a reward of each solved puzzle in a sequence of them. We model it as a sequential game with imperfect information, in which miners have to choose whether or not to report their success. We show that the game has a multiplicity of equilibria and we analyze the parameter constellations for each of them. In particular, the minimum requirement to find it optimal not to report is decreasing with the number of miners who are not reporting, and increasing the heterogeneity among players reduces the likelihood that they choose not to report.
Joseph Y. Halpern, Rafael Pass
At the heart of the Bitcoin is a blockchain protocol, a protocol for achieving consensus on a public ledger that records bitcoin transactions. To the extent that a blockchain protocol is used for applications such as contract signing and making certain transactions (such as house sales) public, we need to understand what guarantees the protocol gives us in terms of agents' knowledge. Here, we provide a complete characterization of agent's knowledge when running a blockchain protocol using a variant of common knowledge that takes into account the fact that agents can enter and leave the system, it is not known which agents are in fact following the protocol (some agents may want to deviate if they can gain by doing so), and the fact that the guarantees provided by blockchain protocols are probabilistic. We then consider some scenarios involving contracts and show that this level of knowledge suffices for some scenarios, but not others.
Rafael Pass, Elaine Shi
Nakamoto's famous blockchain protocol enables achieving consensus in a so-called permissionless setting---anyone can join (or leave) the protocol execution, and the protocol instructions do not depend on the identities of the players. His ingenious protocol prevents "sybil attacks" (where an adversary spawns any number of new players) by relying on computational puzzles (a.k.a. "moderately hard functions") introduced by Dwork and Naor (Crypto'92). Recent work by Garay et al (EuroCrypt'15) and Pass et al (manuscript, 2016) demonstrate that this protocol provably achieves consistency and liveness assuming a) honest players control a majority of the computational power in the network, b) the puzzle-hardness is appropriately set as a function of the maximum network delay and the total computational power of the network, and c) the computational puzzle is modeled as a random oracle. Assuming honest participation, however, is a strong assumption, especially in a setting where honest players are expected to perform a lot of work (to solve the computational puzzles). In Nakamoto's Bitcoin application of the blockchain protocol, players are incentivized to solve these puzzles by receiving rewards for every "block" (of transactions) they contribute to the blockchain. An elegant work by Eyal and Sirer (FinancialCrypt'14), strengthening and formalizing an earlier attack discussed on the Bitcoin forum, demonstrates that a coalition controlling even a minority fraction of the computational power in the network can gain (close to) 2 times its "fair share" of the rewards (and transaction fees) by deviating from the protocol instructions. In contrast, in a fair protocol, one would expect that players controlling a φ fraction of the computational resources to reap a φ fraction of the rewards.
Ivan Katanić
2009. pojavljuje se prva uspješna implementacija elektroničke gotovine koja se ne temelji na centralnom autoritetu već na decentraliziranoj peer-to-peer mreži i kripto- grafskom lancu blokova. Nekoliko godina kasnije pojavljuje se platforma koja omo- gućava izradu decentraliziranih aplikacija povrh lanca blokova. Takvim aplikacijama mogu se implementirati i pametni ugovori, koji se jednom definiraju programskim ko- dom i objave, a zatim se sami izvršavaju, nepromjenjivi i neuništivi. Pomoću platforme i pametnih ugovora implementirali smo decentraliziranu platformu za nagradno rješa- vanje problema koja se ne oslanja na povjerenje u treće strane. Rješili smo i problem tajne objave rješenja usprkos javnosti podataka na lancu blokova, što može biti od koristi u mnogim drugim aplikacijama.
Robert Norvill, Beltrán Borja Fiz Pontiveros, Radu State, Irfan Awan · 5 authors
Smart contracts have recently attracted interest from diverse fields including law and finance. Ethereum in particular has grown rapidly to accommodate an entire ecosystem of contracts which run using its own crypto-currency. Smart contract developers can opt to verify their contracts so that any user can inspect and audit the code before executing the contract. However, the huge numbers of deployed smart contracts and the lack of supporting tools for the analysis of smart contracts makes it very challenging to get insights into this eco-environment, where code gets executed through transactions performing value transfer of a crypto-currency. We address this problem and report on the use of unsupervised clustering techniques and a seed set of verified contracts, in this work we propose a framework to group together similar contracts within the Ethereum network using only the contracts publicly available compiled code. We report qualitative and quantitative results on a dataset and provide the dataset and project code to the research community.
Rune Tevasvold Aune, Adam Krellenstein, Maureen O’Hara, Ouziel Slama
This article examines information leakage when trading in distributed ledgers. We show how the lack of time priority in the period between the publication of a transaction and its validation by miners or designated participants can expose a transaction’s footprint to the market, resulting in potential front-running and manipulation. We propose a cryptographic approach for solving information leakage problems in distributed ledgers that relies on using a hash (or fingerprint) to secure time priority, followed by a second communication that reveals more features of the underlying market transaction—in effect using a transaction’s fingerprint to hide its footprint. Solving the information leakage problem greatly expands the potential applications of private distributed ledger technology to include trading. <b>TOPICS:</b>Quantitative methods, exchanges/markets/clearinghouses
Vincenzo Scoca, Rafael Brundo Uriarte, Rocco De Nicola
A smart contract is the formalisation of an agreement, whose terms are automatically enforced by relying on a transaction protocol, while minimising the need of intermediaries. Such contracts not only specify the service and its quality but also the possible changes at runtime of the terms of agreement. Although smart contracts provide a great deal of flexibility, analysing their compatibility and reaching agreements with this level of dynamism is considerably more challenging, due to the freedom of clients and providers in formulating needs/offers. We introduce a formal language to specify interactions between offers and requests and present a methodology for the autonomous negotiation of smart contracts, which analyses the cost and the necessary changes for reaching an agreement. Moreover, we describe a set of experiments that provides insights on the relative cost of dynamism in negotiating smart contracts and compare the request/offer matching rates of our solution with related works.
Giuseppe Pappalardo, Tiziana Di Matteo, Guido Caldarelli, Tomaso Aste
We investigate Bitcoin network observing transactions broadcasted into the network during a week from 04/05/2016 and then monitoring their inclusion into the blockchain during the following seven months.We unveil that 42% of the transactions are still not included in the Blockchain after 1 h from their appearance and 20% of the transactions are still not included in the Blockchain after 30 days, therefore revealing a great inefficiency in the Bitcoin system. However, we observe that most of these “forgotten” transactions have low values and in terms of transferred value the system is less inefficient with 93% of the transactions value being included into the Blockchain within 3 h and 98.8% within a day. The fact that a sizeable fraction of transactions is not processed timely casts serious doubts on the usability of the Bitcoin Blockchain for reliable time-stamping purposes. It also calls for a debate about the right systems of incentives which a peer-to-peer unintermediated system should introduce to promote efficient transaction recording
Leif-Nissen Lundbæk, Michael Huth
The innovative ideas behind blockchain offer exciting perspectives in research and development of electronic distributed ledger technologies. Bitcoin introduced an "eventual consistency" blockchain with the apparent intent of providing an open and inclusive system for secure, anonymous, yet cost-effective financial transactions based on peer-to-peer computing. It uses Proof ofWork as a cryptographic puzzle to control growth of a chain and to strengthen the resiliency of a chain against subsequent rewrite attempts. Commercial sectors and the public sector have realized the potential of this technical approach, and we now see a number of blockchains that may be called private, closed or permissioned - and that may eschew the values inherent in the design of Bitcoin type systems. From a value-neutral research perspective, there are no clear definitions of blockchain attributes such as "private" or "permissioned", nor is there typically a good understanding of the trust assumptions that clients must make when using such services - for example in systems that do not rely on Proof of Work but on a limited and controlled set of consensus-creating agents. We believe that more research in this direction could establish firm foundations for domain-specific or coalition-specific blockchains, and that such underpinnings would offer novel trust architectures beyond those provided by completely open/public blockchains and third-party operated, closed/private blockchains.
Lian Yu, Wei‐Tek Tsai, Guannan Li, Yafe Yao · 6 authors
Business processes are often related to operational processes, contracts, and regulations. Modeling such processes needs to address regulation monitoring and enforcement, and maintain a reliable history of data for evidence. This paper proposes modeling business processes as smart contracts (SCs) on permissioned blockchains (BCs). The challenges with the proposed approach are state synchronizations among distributed nodes (called authnodes), and real-time requirements. This paper separates the executions of SCs from the state managements on multi-BCs, and proposes a pipeline model to verify and create blocks in parallel.
Katrin Tinn
No abstract is available for this record.
Felipe de Oliveira Simoyama, Ian Grigg, Ricardo Luiz Pereira Bueno, Ludmila Cavarzere De Oliveira
Legislation generally requires public agencies to account for their activity to the public. Among the many duties imposed by legislatures around the world are requirements for transparency in procurement of services, budgeting and presentation of accounts. However, agencies in countries with high corruption problems have trouble complying with the legislation, especially in smaller agencies. Moreover, it is typically infeasible for national auditors to audit all the accounts rendered, and instead, they select a small sample for audit based on their level of risk. Another problem is that the presentation of accounts occurs once a year for all agencies, leading to a seasonal demand with significant lag time between auditing and accounting period. In this study, we present a non-technical framework based on the emerging technology of blockchain that could be a solution to all these concerns. We apply it within the context of Brazilian legislation and the Federal Court of Accounts of Brazil (TCU), although the proposal is applicable across a wide range of countries facing severe corruption.
Lin Chen, Lei Xu, Zhimin Gao, Nolan Shah · 6 authors
Transaction system build on top of blockchain, especially smart contract, is becoming an important part of world economy. However, there is a lack of formal study on the behavior of users in these systems, which leaves the correctness and security of such system without a solid foundation. Unlike mining, in which the reward for mining a block is fixed, different execution results of a smart contract may lead to significantly different payoffs of users, which gives more incentives for some user to follow a branch that contains a wrong result, even if the branch is shorter. It is thus important to understand the exact probability that a branch is being selected by the system. We formulate this problem as the (+-)-Biased Ballot Problem as follows: there are n voters one by one voting for either of the two candidates A and B. The probability of a user voting for A or B depends on whether the difference between the current votes of A and B is positive or negative. Our model takes into account the behavior of three different kinds of users when a branch occurs in the system -- users having preference over a certain branch based on the history of their transactions, and users being indifferent and simply follow the longest chain. We study two important probabilities that are closely related with a blockchain based system - the probability that A wins at last, and the probability that A receives d votes first. We show how to recursively calculate the two probabilities for any fixed n and d, and also discuss their asymptotic values when n and d are sufficiently large.
Patrick McCorry, Ethan Heilman, Andrew Miller
No abstract is available for this record.