Yackolley Amoussou-Guenou, Bruno Biais, Maria Potop-Butucaru, Sara Tucci-Piergiovanni
We analyze from the game theory point of view Consensus-based blockchains when participants exhibit rational or Byzantine behavior. Our work is the first to model the Byzantine-consensus based blockchains as a committee coordination game. Our first contribution is to offer a game-theoretical methodology to analyze equilibrium interactions between Byzantine and rational committee members in Consensus-based blockchains.Byzantine participants seek to inflict maximum damage to the system, while rational participants best-respond to maximize their expected net gains. Our second contribution is to derive conditions under which consensus properties are satisfied or not in equilibrium. When the number of votes required for a decision is lower than the proportion of Byzantine participants, invalid blocks are accepted in equilibrium. When the number of votes needed is large, equilibrium can involve coordination failures, in which no block is ever accepted. However, when the cost of accepting invalid blocks is large, there exists an equilibrium in which blocks are accepted if and only if they are valid.
Driven by the vision of the Internet of Things (IoT) under the fifth-generation (5G) wireless network, computing resource trading attracts numerous attention from both academia and industry. Prior works mainly focus on the design of auction mechanisms to implement pricing and resource allocation. However, it is still a challenging problem because of the following three aspects: 1) How to ensure that the auction mechanism runs fairly? An auction mechanism is vulnerable and questionable since the auctioneer may fail the orders matching operation or collude with a few peers. 2) It's hard to assign the computing resources of providers to customers and guarantee reasonable rewards for each participator. 3) How to make bidding strategies for each participator? Each participator has its willingness to selWuy, which are time-variant and private. To address the above issues, we build a blockchain-enabled computing resource trading system that takes both pricing and bidding strategies into consideration, on which providers and customers can trade computing resources securely, safely and willingly. Next, we formulate a decision-making problem in the continuous double auction (CDA) to maximize their payoffs. Then, we propose a universal model-free Deep Reinforcement Learning (DRL) framework for both computing resource providers and customers. We conduct extensive experiments to evaluate the performance of our DRL framework. Simulation results show that our solution outperforms others in both static and dynamic scenarios. Our DRL framework can achieve higher rewards than others by at least 35%. Furthermore, the average trading price from our DRL framework is less volatile than that from the compared methods. The DRL framework promotes trading and brings larger trading quantities, thus resulting in higher social welfare by at least 25% than the compared schemes.
Philip Daian, Steven Goldfeder, Tyler Kell, Yunqi Li · 8 authors
Blockchains, and specifically smart contracts, have promised to create fair and transparent trading ecosystems.Unfortunately, we show that this promise has not been met. We document and quantify the widespread and rising deployment of arbitrage bots in blockchain systems, specifically in decentralized exchanges (or "DEXes"). Like high-frequency traders on Wall Street, these bots exploit inefficiencies in DEXes, paying high transaction fees and optimizing network latency to frontrun, i.e., anticipate and exploit, ordinary users' DEX trades.We study the breadth of DEX arbitrage bots in a subset of transactions that yield quantifiable revenue to these bots. We also study bots' profit-making strategies, with a focus on blockchain-specific elements. We observe bots engage in what we call priority gas auctions (PGAs), competitively bidding up transaction fees in order to obtain priority ordering, i.e., early block position and execution, for their transactions. PGAs present an interesting and complex new continuous-time, partial-information, game-theoretic model that we formalize and study. We release an interactive web portal, frontrun.me, to provide the community with real-time data on PGAs. We additionally show that high fees paid for priority transaction ordering poses a systemic risk to consensus-layer security. We explain that such fees are just one form of a general phenomenon in DEXes and beyond-what we call miner extractable value (MEV)-that poses concrete, measurable, consensus-layer security risks. We show empirically that MEV poses a realistic threat to Ethereum today. Our work highlights the large, complex risks created by transaction-ordering dependencies in smart contracts and the ways in which traditional forms of financial-market exploitation are adapting to and penetrating blockchain economies.
Cong T. Nguyen, Diep N. Nguyen, Dinh Thai Hoang, Hoang-Anh Pham · 6 authors
Roaming fraud is one of the most significant financial losses for mobile service providers. The inefficiency of current exchanging data management methods among mobile service providers is the main obstacle for roaming fraud prevention. In this paper, we introduce a novel blockchain-based data exchange management system to address roaming fraud problems in mobile networks. This system provides a secure and automatic data exchange service among mobile service providers and mobile subscribers. In addition, we introduce an emerging Proof-of-Stake (PoS) consensus mechanism for the proposed blockchain-based roaming fraud prevention system, which can significantly reduce the delay in exchanging information as well as implementation costs for mobile service providers. To further enhance benefits and security efficiency for the proposed blockchain system, we develop an economic model based on Stackelberg game. This game model is very effective in maximizing profits for both the stakeholders and stake pool and useful in designing a robust blockchain-based mobile roaming management system. Through performance analysis and numerical results, we show that our proposed framework not only provides an effective solution to prevent mobile roaming fraud but also opens many business opportunities for future mobile networks.
The increasing demand for clean, sustainable and reliable energy sources that are secure and stable requires the integration of renewable and edge energy products with the existing power grid. With the introduction of technological advancements and distributed resources, energy users (aka prosumers) can now generate, store and manage their energy requirements, and share their resources with others. BC is a promising technology that can provide secure and verifiable transactions for P2P energy trading, and promote energy conservation. This article recognizes the best practices for sustainable energy, and highlights the benefits of BC and smart contracts in the energy sector. A distributed trading framework and smart contracts are proposed for future versions of BC and integration with other energy products, and potential solutions are suggested.
The EVM language is a simple stack-based language with words of 256 bits, with one significant difference between the EVM and other virtual machine languages (like Java Bytecode or CLI for .Net programs): the use of the stack for saving the jump addresses instead of having it explicit in the code of the jumping instructions. Static analyzers need the complete control flow graph (CFG) of the EVM program in order to be able to represent all its execution paths. This report addresses the problem of obtaining a precise and complete stack-sensitive CFG by means of a static analysis, cloning the blocks that might be executed using different states of the execution stack. The soundness of the analysis presented is proved.
Smart contract is a disruptive FinTech that is signed in advance and automatically executed when the goods are received. Therefore, the buyer will settle accounts without delay payment under smart contract, which benefits the supplier in B2B transactions. However, how to motivate the buyer to participate in smart contract? In this paper, we consider a supplier selling goods through retailers such as Wal-Mart in a co-opetitive supply chain, where the retailer buys and resells the supplier's goods and the supplier encroaches on the market by opening a direct channel. Without smart contract, the supplier incurs cash opportunity cost because of the retailer's delay payment (referred to as Traditional Contract scenario). With smart contract, the retailer needs to pay the supplier immediately when the goods arrive (referred to as Smart Contract scenario). We use Generalized Nash Bargaining to formulate the contract negotiation, and show that the adoption of smart contract changes the competition and cooperation between the supplier and the retailer both vertically and horizontally. We find that, when the supplier's unit cash opportunity cost is high (low), the smart contract enhances (weakens) the coordination in the reselling channel, increases (decreases) the reselling channel's market share compared to the direct-selling channel, and increases (lowers) the retailer's proportion in the reselling revenue. Interestingly, we show that, when the supplier's bargaining power is moderate or extremely low, it prefers traditional contract when the unit cash opportunity cost is moderate. We also show that, the retailer and the supplier have incentive alignment to adopt smart contract when the supplier's unit cash opportunity cost is high. We further study the impact of the supplier's merchant discount fee under traditional contract and its commission cost when the direct channel is an online store, finding that our main results are qualitatively unchanged.
The performance of existing permissionless smart contract platforms such as Ethereum is limited by the consensus layer. Prism is a new proof-of-work consensus protocol that provably achieves throughput and latency up to physical limits while retaining the strong guarantees of the longest chain protocol. This paper reports experimental results from implementations of two smart contract virtual machines, EVM and MoveVM, on top of Prism and demonstrates that the consensus bottleneck has been removed. Code can be found at https://github.com/wgr523/prism-smart-contracts.
Guido Felipe Valderrama Herrera, Leonardo Garcia Sanchez
Este trabajo analiza la relación que tienen las ventas en corto, los sesgos de los agentes junto la interacción de los fundamentales de oferta y demanda respecto la formación de precios en el mercado del Bitcoin. Dentro del análisis encontramos que las tendencias aportadas en la literatura se mantienen en cuanto a las ventas en corto y sus restricciones a pesar de no encontrar evidencia estadística.
This paper presents a Blockchain-based voting mechanism that has the potential to disrupt current voting systems and fuel the development of decentralized governance. More specifically, the paper presents a study on the design and deployment of a Solidity smart contract that can interact with any Ethereum-based token (ERC-20) in order to help decentralized organizations to run public voting campaigns while at the same time engaging tokens holders in decision making. The use case scenarios outlined in the paper demonstrate with success the effectiveness of the proposed approach.
Smart contracts are a common topic in scientific discussions held by computer scientists. Due to the dynamic nature of its applications, smart contracts must be considerably more adaptable, responsive and controllable. Yet the longstanding focus on security issues has affected negatively the development of smart contracts in the transfer of ownership of the real estate.In this paper, we study the possibilities and the limitations of how to transfer properties on the block chain using a digital record, as a back- support in case of litigation. We propose storing a registry catalog to handle the property historical data and criminal record of the owners. The execution of the smart contract is enforced using a digital identity of the two parties. We design the components of what the registry should contain to integrate with block chain infrastructure and we also analyze and discuss the government endorsement needed for the success of the implementation.
Block chain technology provides a decentralized and secure platform for executing transactions. Smart contracts in Ethereum have been proposed as the mechanism to automate legal contracts securely without the involvement of third parties. Yet, there are still several issues to be resolved especially regarding the updating of smart contracts in blockchain as well as the use of blockchain as part of a legal smart contracts system. In this work we propose a methodology and an architecture for building and deploying legal contracts in the blockchain. As the blockchain is immutable, we cannot update the code of the smart legal contracts, but in real life applications updating of contracts is a requirement that cannot be ignored. In this paper we address the problem of contract update by introducing a new versioning system that keeps track of the changes and links the different versions using a linked list. Moreover, we propose a system architecture where the user interface, the application logic and the blockchain are smoothly integrated in a manner that each part of the system contributes for producing a flexible and transparent execution. We show the applicability of our approach by implementing a system for the case of a rental agreement.
Cilj ovog rada je otkriti i proširiti moje znanje o distribuiranim mrežama i teoriji aukcija izradom koncept aplikacije za aukcije na Ethereum mreži koristeći pametne ugovore. Nezamjenjivi tokeni koriste se za stvaranje digitalne povjerljivosti, a prvi put bili su implementirani koristeći Ethereum ERC721 token standard. NFT-Auction-dapp je aplikacija bazirana na Ethereumu koja omogućuje korisnicima da kreiraju i sudjeluju u aukcijama NFT tokena u stvarnom vremenu, na globalnoj i distribuiranoj mreži, zadržavajući garancije plaćanja i dostave. U radu ću se služiti znanjima koja sam stekao tijekom studija na Visokom učilištu Algebra i znanjima koja sam stekao samostalno kako bih izgradio aplikaciju, objavio ju na javnu Ethereum mrežu i testirao njezinu funkcionalnost.
Blockchain technology and artificial intelligence (AI) are current hot topics\nin research and practice. However, the potentials of their combination have\nbeen studied just recently to a larger extend. While different use cases for\ncombining AI and blockchain have been discussed, the idea of enabling\nblockchain-based smart contracts to perform "smarter" decisions by using AI or\nmachine learning (ML) models has only been considered on the conceptual level\nso far. It remained open, how such AI-enabled smart contracts could be\nimplemented in a robust way for real-world applications. Therefore, in this\npaper a new, enterprise-class implementation of AI-enabled smart contracts is\npresented and first insights regarding its feasibility are discussed.\n
Background: Executing, verifying and enforcing credible transactions on permissionless blockchains is done using smart contracts. A key challenge with smart contracts is ensuring their correctness and security. Several test input generation techniques for detecting vulnerabilities in smart contracts have been proposed in the last few years. However, a comparison of proposed techniques to gauge their effectiveness is missing. Aim: This paper conducts an empirical evaluation of testing techniques for smart contracts. The testing techniques we evaluated are: (1) Blackbox fuzzing, (2) Adaptive fuzzing, (3) Coverage-guided fuzzing with an SMT solver and (4) Genetic algorithm. We do not consider static analysis tools, as several recent studies have assessed and compared effectiveness of these tools. Method: We evaluate effectiveness of the test generation techniques using (1) Coverage achieved - we use four code coverage metrics targeting smart contracts, (2) Fault finding ability - using artificially seeded and real security vulnerabilities of different types. We used two datasets in our evaluation - one with 1665 real smart contracts from Etherscan, and another with 90 real contracts with known vulnerabilities to assess fault finding ability. Result: We find Adaptive fuzzing performs best in terms of coverage and fault finding over contracts in both datasets. Conclusion: However, we believe considering dependencies between functions and handling Solidity specific features will help improve the performance of all techniques considerably.
The confluence of Internet of Things(IoT) , Blockchain(BC) and Artificial Intelligence(AI) acts as a key accelerator for enabling Machine Economy. To be ready for future businesses these technologies needs to be adapted by extending the IoT capabilities to Economy of Things (EoT) capabilities. In this paper we focus on one such implementation experience for Smart Toll Transaction application in the domain of mobility. Our paper showcases a possible solution by leveraging negotiations, decision making, distributed learning capabilities at the devices level using AI-enabled Multi-Agent Systems and the real-time smart contracts between the Cars and Tolls using Blockchain. This solution also showcases the monetization of real time data coming from various IoT devices which are part of vehicles and infrastructure. While blockchain secures the privacy of the participants it also acts as an economic transactional layer and governance layer between the devices in the networ
Block chain is the latest technology in the IT industry for securing blocks of data. Secure online bidding system is designed with blockchain technology using hyper ledger saw tooth framework. Currently, there is a lot of data integrity problems with respect financial services in the market. Block chain overcomes this flaw by decentralizing the information. In the proposed work, the client can connect to the validator network to put an item or commodity of their choice for auction. Other users can view the items and connect to the validator network to bid their items using user interface. All the information regarding the items are stored on the Blockchain. Information is safe and integrity is achieved. Detailed records cannot be altered and the highest bidder has to make the purchase. Once the purchase is done, nobody can alter the data. Information is safe and integrity is achieved as both seller and bidder are enabled with security.
The emerging e-commerce systems open the way for several applications to be viable from off-line to online system. E-Auction is an effective ecommerce system that allows bidders and sellers to interact through online platforms. However, providing completely secure e-auction system that satisfies security conditions for all players in these systems requires very complex efforts in the traditional design. Blockchain and smart contract, as a revolutionary technology, has attracted the interest of different industries including the designing of e-auction systems. In this paper, our aim is to provide a prototype of secure blockchain e-auction system that lowering the uncertainties about identities of long-distance complex trade in an e-auction system that can be implemented in UAE services, especially, UAE Auction. In our implementation, we use smart contract in order to guarantee the necessary security requirements. The smart contract contains important information about the transaction details such as auctioneer data, the start time and the deadline of auction, the current winner data, and the current highest price.
Blockchain technology is the distributed, decentralised ledger technology underlying Bitcoin and other cryptocurrencies. We apply Oliver Williamson’s transactions cost analysis to the blockchain consensus mechanism. Blockchains reduce the costs of opportunism but are not ‘trustless’. We show that blockchains are trust machines. Blockchains are platforms for three-sided bargaining that convert energy-intensive computation into economically-valuable trust.
Στην παρούσα διπλωματική εργασία σχεδιάστηκε και υλοποιήθηκε μία κατανεμημένη εφαρμογή ηλεκτρονικών δημοπρασιών αξιοποιώντας την τεχνολογία του blockchain. Παρέχονται στον χρήστη οι δυνατότητες δημιουργίας ανοιχτών ανοδικών δημοπρασιών, η εύρεση των ενεργών και των ολοκληρωμένων δημοπρασιών. καθώς και η δυνατότητα υποβολής προσφοράς. Η υλοποίηση έγινε χρησιμοποιώντας το δημόσιο blockchain του ethereum, υλοποιώντας smart contracts γραμμένα στην γλώσσα προγραμματισμού solidity. Παράλληλα, για την διεπαφή του χρήστη με το blockchain χρησιμοποιήθηκαν τεχνολογίες διαδικτύου όπως τα frameworks Laravel, Vue.js, web3.js.