Follow blockchain research across journals, conferences, and preprint repositories.
13,597 results · page 553 of 567
Meixun Qu, Xin Huang, Chen Xu, Yi Wang · 6 authors
No abstract is available for this record.
Christian Colombo, Joshua Ellul, Gordon J. Pace
No abstract is available for this record.
Lara Mauri, Stelvio Cimato, Ernesto Damiani
Blockchain technology is having a deep impact on the financial and technical sectors providing a mechanism for the creation of decentralized currencies and a number of applications in different fields.At the core of the technology there is a consensus protocol enabling the maintenance of a distributed ledger.In general current systems are complex schemes that implement a combination of cryptographic algorithm, distributed techniques, and incentive driven behaviour.In this paper we focus on three of the most diffused platforms, i.e.Bitcoin, Ripple, and Ethereum, and provide a comparative analysis of their most important features such as the architecture, the scripting language, the economic and security properties.
Valerio Celeste, Shaen Corbet, Constantin Gurdgiev
No abstract is available for this record.
Seied Hoseini
Blockchain is a technology to exchange digital assets including cryptocurrencies, data, software, patents etc. Blockchain is designed in various types depending on different architectures and configurations for different purposes. The mathematical and cryptographic mechanisms and consensus algorithms, implemented in the Blockchain, guarantee trust, security, integrity and availability of transactions between participants. \nThis thesis is aimed to consider mathematical foundation and algorithmic aspects of Ethereum from the base network to high level of its functionality with the comparison to mathematical mechanisms of Bitcoin. In this thesis we describe Ethereum as stack of layers. Our mission is to extract cryptographic and mathematical mechanisms implemented in each layer. \nWe present how hash function is utilized to construct cost function and Hashcash protocol. Hashcash protocol is implemented in Proof of Work (PoW) mechanism. Also, we explain how hash function is used to connect blocks in the chain of blocks and how hash function is used to organize transactions in a Merkle tree and in a Merkle-Patricia-trie. \nThis thesis describes how Elliptic Curve Digital Signature Algorithm (ECDSA) and Lamport signing algorithm provide integrity of transactions. Elliptic Curve Integrated Encryption Scheme (ECIES) is hybrid encryption scheme which is utilized to provide confidentiality of transactions. The Elliptic Curve Cryptography (ECC) is used to disguise identities in both Bitcoin and Ethereum network. The new approaches to provide privacy are Ring signatures and Zk-Snarks. \nThis thesis also explains Bloom filter structure in Ethereum. The Bloom filter is a probabilistic data structure to test membership of elements in big data bases.
Lars Stegeman
Ethereum is a decentralized blockchain platform. On this platform smart contracts are deployed and executed. Smart contracts are also called executable code on the It can perform calculations, store information and send/receive transactions. Since these smart contracts control a virtual currency, vulnerabilities can be costly. The code of smart contracts is public and changes to it are impossible since they are committed to the blockchain. Many techniques and tools can be used to detect these vulnerabilities. Formal verification proves a specification against all possible input on a certain contract, while testing only guarantees correct output for a given input. This thesis introduces the tool Solitor. Solitor is short for Solidity (runtime) monitor, and uses runtime verification as a technique to make smart contracts more secure. It enables users to specify the behaviour of a contract using annotations. It is a tool developed specifically for smart contracts on the Ethereum network. We define an annotation language to specify the requirements on a smart contract. Solitor can parse and translate these annotations in Solidity contracts to Solidity code which checks the annotation at runtime.
Massimo Bartoletti, Roberto Zunino
A landmark security property of smart contracts is liquidity: in a non-liquid contract, it may happen that some funds remain frozen. The relevance of this issue is witnessed by a recent liquidity attack to the Ethereum Parity Wallet, which has frozen $${\sim }160M$$ USD within the contract, making this sum unredeemable by any user. We address the problem of verifying liquidity of Bitcoin contracts. Focussing on BitML, a contracts DSL with a computationally sound compiler to Bitcoin, we study various notions of liquidity. Our main result is that liquidity of BitML contracts is decidable, in all the proposed variants. To prove this, we first transform the infinite-state semantics of BitML into a finite-state one, which focusses on the behaviour of any given set of contracts, abstracting the context moves. With respect to the chosen contracts, this abstraction is sound and complete. Our decision procedure for liquidity is then based on model-checking the finite space of states of the abstraction.
Lijing Zhou, Licheng Wang, Yiru Sun, Pin Lv
Currently, Internet of Things (IoT) and blockchain technologies are experiencing exponential growth in academia and industry. Generally, IoT is a centralized system whose security and performance mainly rely on centralized servers. Therefore, users have to trust the centralized servers; in addition, it is difficult to coordinate external computing resources to improve the performance of IoT. Fortunately, the blockchain may provide this decentralization, high credibility and high security. Consequently, blockchain-based IoT may become a reasonable choice for the design of a decentralized IoT system. In this paper, we propose a novel blockchain-based threshold IoT service system: BeeKeeper. In the BeeKeeper system, servers can process a user's data by performing homomorphic computations on the data without learning anything from them. Furthermore, any node can become a leader's server if the node and the leader desire so. In this way, BeeKeeper's performance can continually increase by attracting external computing resources to join in it. Moreover, malicious nodes can be scrutinized. In addition, BeeKeeper is fault tolerant since a user's BeeKeeper protocol may work smoothly as long as a threshold number of its servers are active and honest. Finally, we deploy BeeKeeper on the Ethereum blockchain and give the corresponding performance evaluation. In our experiments, servers can generate their response with about 107 ms. Moreover, the performance of BeeKeeper mainly depends on the blockchain platform. For instance, the response time is about 22.5 s since the block interval of Ethereum blockchain is about 15 s. In fact, if we use some other blockchain with short block interval, the response time may be obviously short.
Marian Gidea, Daniel Goldsmith, Yuri Katz, Pablo Roldan · 5 authors
We analyze the time series of four major cryptocurrencies (Bitcoin, Ethereum, Litecoin, and Ripple) before the digital market crash at the end of 2017 - beginning 2018. We introduce a methodology that combines topological data analysis with a machine learning technique -- $k$-means clustering -- in order to automatically recognize the emerging chaotic regime in a complex system approaching a critical transition. We first test our methodology on the complex system dynamics of a Lorenz-type attractor, and then we apply it to the four major cryptocurrencies. We find early warning signals for critical transitions in the cryptocurrency markets, even though the relevant time series exhibit a highly erratic behavior.
Zheng Yang, Hang Lei
In recent publications, we presented a novel formal symbolic process virtual machine (FSPVM) framework that combined higher-order theorem proving and symbolic execution for verifying the reliability and security of smart contracts developed in the Ethereum blockchain system without suffering the standard issues surrounding reusability, consistency, and automation. A specific FSPVM, denoted as FSPVM-E, was developed in Coq based on a general, extensible, and reusable formal memory (GERM) framework, an extensible and universal formal intermediate programming language, denoted as Lolisa, which is a large subset of the Solidity programming language that uses generalized algebraic datatypes, and a corresponding formally verified interpreter for Lolisa, denoted as FEther, which serves as a crucial component of FSPVM-E. However, our past work has demonstrated that the execution efficiency of the standard development of FEther is extremely low. As a result, FSPVM-E fails to achieve its expected verification effect. The present work addresses this issue by first identifying three root causes of the low execution efficiency of formal interpreters. We then build abstract models of these causes, and present respective optimization schemes for rectifying the identified conditions. Finally, we apply these optimization schemes to FEther, and demonstrate that its execution efficiency has been improved significantly.
Zheng Yang
This paper reports on the development and verification of a novel formal symbolic process virtual machine (FSPVM) for verifying the reliability and security of Ethereum smart contracts, denoted as FSPVM-E, completely in Coq proof assistant. It adopts execution-verification isomorphism (EVI), an extension of Curry-Howard isomorphism (CHI), as its fundamental theoretical framework. The current version of FSPVM-E is constructed on a general, extensible, and reusable formal memory (GERM) framework, an extensible and universal formal intermediate programming language Lolisa, which is a large subset of the Solidity programming language using generalized algebraic datatypes, and the corresponding formally verified interpreter of Lolisa, denoted as FEther. It supports the ERC20 standard and can automatically simultaneously symbolically execute the smart contract programs of Ethereum and verify their reliability and security properties using Hoare logic in Coq. In addition, this work, contributes to solving the problems of automation, inconsistency and reusability in higher-order logic theorem proving.
Henry Kim, Marek Laskowski, Ning Nan
At the beginning of 2018, there is a growing belief that blockchain technologies constitute a revolutionary innovation in how we transfer value electronically. In that vein, blockchain may be a suitable complement to ontologies to achieve a big part of the vision of the semantic Web by Tim Berners-Lee. We believe that if this complementarity is to be achieved blockchain and ontologies must co-evolve. In this paper, we focus on what and how to engineer models, methods, designs, and implementations for this co-evolution. As a first step in this co-evolution, we propose a conceptual design of a governance ontology represented as meta-data tags to be embedded and instantiated in a smart contract at the blockchain protocol level. We develop this design by examining and analyzing smart contracts from the infamous The DAO experiment on the Ethereum blockchain. We believe there are two contributions of this paper: it serves to inform and implore the blockchain and ontology communities to recognize and collaborate with each other; and it outlines a roadmap for engineering artifacts to bridge the gap between blockchain community focus on protocol-level blockchain interoperability and the ontology community focus on semantic-level interoperability.
Debajani Mohanty
Now that you are proficient in smart contract development using Solidity, let’s deploy a contract on an Ethereum network. Deployment can be done in many ways. 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.
Bikramaditya Singhal, Gautam Dhameja, Priyansu Sekhar Panda
In the previous chapter we learned how to programmatically interact with Bitcoin and Ethereum blockchains using JavaScript. We also touched on how to create and deploy Ethereum smart contracts. In this chapter we will take our blockchain application programming to the next level by learning how to develop and deploy a DApp based on the Ethereum blockchain. As part of creating this DApp, we will be setting up a private Ethereum network and then we will use this network as the underlying blockchain for our DApp. This DApp will have its business logic in an Ethereum smart contract, and this logic will be executed using a web application connecting to private Ethereum network. This way, we intend to cover all aspects of Ethereum application development— from setting up nodes and networks, to creating and deploying a smart contract, to executing smart contract functions using client applications.
Kedar Iyer, Chris Dannen
This chapter is the first of our applied practice chapters. It walks through the two fundamental Ethereum interactions. In the first project, we will broadcast a transaction to three Ethereum networks. In the second project, we will deploy a simple Hello World contract.
Lauren Rhue
No abstract is available for this record.
Trishita Tiwari, David Starobinski, Ari Trachtenberg
No abstract is available for this record.
An Zhang, Kunlong Zhang
No abstract is available for this record.
Matteo Marescotti, Martin Blicha, Antti E. J. Hyvärinen, Sepideh Asadi · 5 authors
No abstract is available for this record.
Hisham S. Galal, Amr Youssef
No abstract is available for this record.
Tim Leung, Hung Cuong Nguyen
Purpose This paper aims to present a methodology for constructing cointegrated portfolios consisting of different cryptocurrencies and examines the performance of a number of trading strategies for the cryptocurrency portfolios. Design/methodology/approach The authors apply a series of statistical methods, including the Johansen test and Engle–Granger test, to derive a linear combination of cryptocurrencies that form a mean-reverting portfolio. Trading systems are designed and different trading strategies with stop-loss constraints are tested and compared according to a set of performance metrics. Findings The paper finds cointegrated portfolios involving four cryptocurrencies: Bitcoin (BTC), Ethereum (ETH), Bitcoin Cash (BCH) and Litecoin (LTC), and the corresponding trading strategies are shown to be profitable under different configurations. Originality/value The main contributions of the study are the use of multiple altcoins in addition to bitcoin to construct a cointegrated portfolio, and the detailed comparison of the performance of different trading strategies with and without stop-loss constraints.
Κωνσταντίνος Γκίλλας, Stelios Bekiros, Costas Siriopoulos
In this paper, we study the contemporaneous tail dependence structure in a pairwise comparison of the ten largest cryptocurrencies, namely Bitcoin, Dash, Dogecoin, Ethereum, Litecoin, Monero, Namecoin, Novacoin, Peercoin, and Ripple. We apply multivariate extreme value theory and we estimate a bias-corrected extreme correlation coefficient. Our findings reveal clear patterns of significantly high bivariate dependency in the distribution tails of some of the most basic and widespread cryptocurrencies, primarily over various downside constraints. This means that extreme correlation is not related to cryptocurrency market volatility per se, but to the trend of the cryptocurrency market. Therefore, extreme correlation increases in bear markets, but not in bull markets for these pairs. Interestingly, there is also a significant number of pairs which exhibit a weak level of dependency in distribution tails.
Debajani Mohanty
In previous chapters, you learned about the Ethereum architecture, Solidity programming, and how to debug and deploy using different local and test setups. So far so good; but is that all enough to make you a master in the Ethereum blockchain? The main challenge that the blockchain market faces today is a lack of knowledge about where this technology can be best applied. Business leaders across verticals are struggling to find use cases that would be a good fit for blockchain implementation, and loads of arguments are taking place in this area. As a blockchain expert, it’s your job to dream, innovate, come up with ideas, and advise businesses about where this technology can bring maximum benefits.
Debajani Mohanty
In the past decade, many blockchain and DLT frameworks have flooded the market, but Ethereum is still the favorite of most blockchain lovers. As per a recent report, “Ethereum currently has the most active developer community in the space and has 30 times more developers than the second most active community.” The Ethereum blockchain does have some issues, yet it’s the market leader in its space, and no other framework is anywhere even close to this framework.