Follow blockchain research across journals, conferences, and preprint repositories.
13,597 results · page 526 of 567
Wei-Meng Lee
Now that you have a solid understanding of how a blockchain works, you are ready to connect to the real Ethereum blockchain. To get connected to the Ethereum blockchain, you need an Ethereum client – an application that runs as an Ethereum node on the blockchain. Using an Ethereum client, you can perform tasks such as the following:
Taneli Hukkinen, Juri Mattila, Kari Smolander, Timo Seppälä · 5 authors
In recent years, information systems have not been largely evaluated by their operating costs, but mainly by their strategic benefit and competitive advantage. As blockchain-based decentralized applications become more commonplace, representing a shift towards fully consumption-based distributed computing, a new mode of thinking is required of developers, with meticulous attention to computational resource efficiency. This study improves on a blockchain application designed for conducting microtransactions of electricity in a nanogrid environment. By applying the design science research methodology, we improve the efficiency of the application’s smart contract by 11 %, with further improvement opportunities identified. Despite the results, we find the efficiency remains inadequate for public Ethereum deployment. From the optimization process, we extrapolate a set of general guidelines for optimizing the efficiency of Ethereum smart contracts in any application.
Francesco Buccafurri, Lorenzo Musarella, Roberto Nardone
Web of Trust offers a way to bind identities with the corresponding public keys. It relies on a distributed architecture, where each user could play the role of certificate signer. With the widespread diffusion of social networks, the trust propagation is a matter of growing interest. This paper proposes an approach enabling the propagation in Web of Trust by means of Ethereum. The usage of Ethereum eliminates the necessity of single-organization trusted services, which is, in general, not realistic. Although the information stored on Ethereum is public, the privacy of users is protected because trust chains involve only Ethereum addresses and strong measures are implemented to contrast their malicious de-anonymization. The approach relies on the usage of a smart contract for storing the status of certificate signatures and to manage revocations. When a user u wants to trust another user v, the smart contract checks the presence of trust chains originating from root nodes of u.
Jongbeen Han, Heemin Kim, Hyeonsang Eom, Jonathan Coignard · 6 authors
A blockchain is designed to make consistent and reliable agreement in an unreliable and decentralized environment. It also permits processing transactions, making smart contracts, which allows end users to perform the contracts without any intermediate entities. However, there are some challenges in retrieving the state in a smart contract on the blockchain. For example, an external database or user-defined data structures can be used to retrieve the data from a smart contract in a range, which can increase the management overhead and decrease the overall performance of the blockchain system. In this paper, we propose a scheme that enables SQL query operations in a blockchain system. In our proposed scheme, the register and query managers provide fast retrieval of range data without any user-defined data structure, and management at low cost without any external database, respectively. We have implemented our scheme on quorum which is an Ethereum-based blockchain system and evaluated it using a synthetic benchmark. The experimental results show that our system can improve the search performance up to about 22x compared with the existing system with low memory usage.
Bert-Jan Butijn, Damian A. Tamburri, Willem‐Jan van den Heuvel
This chapter seeks to discredit the popular belief that blockchains will revolutionize or disrupt commerce. More specifically, it aims to clarify that blockchains as such cannot serve as a technology or ideology for the decentralization of online marketplaces. To this end, the chapter examines the interrelated concepts of decentralization, disintermediation, trustlessness, and immutability. It is necessary to understand what those terms actually mean and how they affect actual, commercial practices. The chapter commences with a broad description of blockchains and introduces the important division between public and private blockchains, to demonstrate that only the latter could potentially serve as a technology that could provide a user-friendly and secure transacting environment. It confronts the practical implications of decentralization, focusing on the fact that the absence of formalized control usually translates into an absence of formalized governance processes.
Robert Leonhard
No abstract is available for this record.
Joran J. Honig, Maarten H. Everts, Marieke Huisman
No abstract is available for this record.
Ngoc Tien Thanh Le, Quoc Nghiep, Nguyen Ngoc, Nghia Duong‐Trung · 7 authors
The adoption of decentralized cryptocurrency plat-forms is growing fast, thanks to the implementation of Blockchain technology and smart contracts. It encourages the novel frame-works in a wide range of applications including finance and payment methods such as cash on delivery. However, a large number of smart contracts developed for cash on delivery suffer from fraudulent transactions which enable malicious participants to break the signed contracts without sufficient penalties. A shipper will involve in the system and place a mortgage to ensure reliability. A buyer also pledges an amount of money when making the order. Our process not only ensures the interests of a seller but also prevents a fraud shipper. The penalties will be made in two scenarios: (i) the buyer refuses to receive the commodities without any reliable reasons; and (ii) the shipper attempts to make any modification on the delivered goods during transportation. To help developers create more secure and reliable cash on delivery system, we introduce double smart contracts, a framework rooted in Blockchain technology and Ethereum, to tackle those mentioned problems. We also contribute our solution as an open source software that developers can easily add to their implementation to enhance functionality.
Zakaria Abou El Houda, Abdelhakim Hafid, Lyes Khoukhi
With the exponential growth in the number of insecure devices, the impact of Distributed Denial-of-Service (DDoS) attacks is growing rapidly. Existing DDoS mitigation schemes are facing obstacles due to low flexibility, lack of resources, and high cost. The new emerging technologies, such as blockchain, introduce new opportunities for low-cost, efficient and flexible DDoS attacks mitigation across multiple domains. In this paper, we propose a blockchain-based approach, called Cochain-SC, which combines two levels of mitigation, intra-domain and inter-domain DDoS mitigation. For intra-domain, we propose an effective DDoS mitigation method in the context of software defined networks (SDN); it consists of three schemes: (1) Intra Entropy-based scheme (I-ES) to measure, using sFlow, the randomness of data inside the domain; (2) Intra Bayes-based scheme (I-BS) to classify, based on entropy values, illegitimate flows; and (3) Intra-domain Mitigation (I-DM) scheme to effectively mitigate illegitimate flows inside the domain. For inter-domain, we propose a collaborative DDoS mitigation scheme based on blockchain; it uses the concept of smart contracts (i.e., Ethereum's smart contracts) to facilitate the collaboration among SDN-based domains (i.e., Autonomous System: AS) to mitigate DDoS attacks. For this aim, we design a novel and secure scheme that allows multiple SDN-based domains to securely collaborate and transfer attack information in a decentralized manner. Combining intra- and inter-domain DDoS mitigation, Cochain-SC allows an efficient mitigation along the path of an ongoing attack and an effective mitigation near the origin of the attack. This allows reducing the enormous cost of forwarding packets, across multiple domains, which consist mostly of useless amplified attack traffic. To the best of our knowledge, Cochain-SC is the first scheme that proposes to deal with both intra-domain and inter-domain DDoS attacks mitigation combining SDN, blockchain and smart contract. The implementation of Cochain-SC is deployed on Ethereum official test network Ropsten. Moreover, we conducted extensive experiments to evaluate our proposed approach; the experimental results show that Cochain-SC achieves flexibility, efficiency, security, cost effectiveness, and high accuracy in detecting illegitimate flows, making it a promising approach to mitigate DDoS attacks.
Wei Xiong, Li Xiong
There are two traditional data trading modes, the hosting mode, and the aggregation mode, which depend on the trusted third parties to a large extent. The hosting mode is that the data are completely hosted in the data trading center, so the data trading center retains the data. On the surface, the aggregation mode is that the data trading center is not to retain the data of trading, but actually, it has the ability to retain the data. There is a fundamental difference between the ability to retain the data and the inability to retain the data. These two trading modes cause the data owners to be afraid to share data trading. In this paper, we propose a solution to the data trading mode based on the smart contract using blockchain and machine learning. Our solution takes advantage of the immutability, tamper-proof and traceability of blockchain, the programmability of smart contract, and the verification of data availability by the similarity learning to propose a challenge response mechanism between the data purchaser and the data owner, an off-chain download mechanism between the data purchaser and the data storage service provider, and an arbitration mechanism for the controversy resolution of the data trading. The challenge response mechanism is used to authenticate and authorize the data owner, the off-chain download mechanism is used to authenticate and authorize the data purchaser to download the purchased data, and the similarity learning is used to deal with the controversy over the data availability in the data trading. The design and implementation of data trading smart contract successfully achieved the goal of removing the trusted third party in the data trading, and thus, the problem that the data trading center has the ability to retain the data in the process of the data trading is solved, as well as the automatic payment by using the Ethereum encrypted currency among the trading participants is realized. This paper presents the whole process of smart contract from the design and implementation to the test completion and provides the security analysis and performance evaluation. The full code of smart contract and the ABI interface have been uploaded to the GitHub for the public release.
Haiqing Liu, Yan Zhang, Shiqiang Zheng, Yuancheng Li
In order to realize peer-to-peer (P2P) transactions between electric vehicles (EVs) in vehicle-to-grid (V2G) networks, we propose an EV power trading model based on blockchain and smart contract. Firstly, based on the blockchain and smart contract technology, a decentralized power trading model is proposed to realize the information equivalence and transparent openness of power trading. Then, considering the randomness and uncertainty of EV charging and discharging, the EV trading parties use the reverse auction mechanism based on dynamic pricing strategy to complete the transaction matching, which can not only improve the profit of the less competitive power seller, but also it can reduce the cost of the electricity purchaser. Finally, in order to verify the feasibility of our proposed scheme, V2G's EV power trading smart contract was designed, and the smart contract was released to Ethereum and simulated experiments were carried out. The effectiveness of the proposed scheme is verified by simulation experiments and comparison with traditional power trading schemes.
Seunghyeon Lee, Changhoon Yoon, Heedo Kang, Yeonkeun Kim · 8 authors
The Dark Web is notorious for being a major distribution channel of harmful content as well as unlawful goods.Perpetrators have also used cryptocurrencies to conduct illicit financial transactions while hiding their identities.The limited coverage and outdated data of the Dark Web in previous studies motivated us to conduct an in-depth investigative study to understand how perpetrators abuse cryptocurrencies in the Dark Web.We designed and implemented MFScope, a new framework which collects Dark Web data, extracts cryptocurrency information, and analyzes their usage characteristics on the Dark Web.Specifically, MFScope collected more than 27 million dark webpages and extracted around 10 million unique cryptocurrency addresses for Bitcoin, Ethereum, and Monero.It then classified their usages to identify trades of illicit goods and traced cryptocurrency money flows, to reveal black money operations on the Dark Web.In total, using MFScope we discovered that more than 80% of Bitcoin addresses on the Dark Web were used with malicious intent; their monetary volume was around 180 million USD, and they sent a large sum of their money to several popular cryptocurrency services (e.g., exchange services).Furthermore, we present two real-world unlawful services and demonstrate their Bitcoin transaction traces, which helps in understanding their marketing strategy as well as black money operations.
Purathani Praitheeshan, Yi Wei Xin, Lei Pan, Robin Doss
No abstract is available for this record.
Francisco José Couto da Silva, Sebastian Bro Damsgaard, Mikki Alexander Mousing Sørensen, Flavien Marty · 8 authors
Blockchain systems are on the rise, especially after the introduction and popularization of Bitcoin. The potential of the technology has been expanded and rebooted by Ethereum to support a broader range of applications through smart contracts. Transactions and contracts are activated every day in the Ethereum network and blocks are created at a very high rate. Often blocks are mined at conflicting times, which causes a split on the chain or a fork. Forks pose an inconsistency problem on the network until they are solved and the network agrees on the same instance of the blockchain. Transactions included on side forks, once the fork is resolved, are discarded and have to be mined again. Fork rates also impact the overall performance of the blockchain and the security of the system. This work studies how one of the main networking factors, namely communication delay, impacts forking of the blockchain. An analytical model for forking probability is presented. Furthermore, the impact of block distribution delays on the amount of forks is quantified using a private Ethereum blockchain in controlled experiments in a lab.
J. J. Song, Hong S. He, Zhuo Lv, Chunhua Su · 6 authors
No abstract is available for this record.
Philipp Schindler, Aljosha Judmayer, Nicholas Stifter, Edgar Weippl
No abstract is available for this record.
Muhammad Faizan, Thomas Brenner, Felix Foerster, Christof Wittwer · 5 authors
In the past decade, there has been a significant increase in distributed energy resources. This transformation has rendered the grid more bidirectional and transformed many small consumers into prosumers. However, these small power producers are not able to optimize their revenue since, currently, they can only sell to local energy suppliers or opt to sell at a fixed feed-in tariff. If intermediaries are eliminated from energy trading, both individual buyers and prosumers can increase their profitability. Blockchain technology could facilitate this scenario. In this paper, the simulated environment of a hierarchical energy trading market using Ethereum’s smart-contract technology is created as a proof-of-concept of using blockchain technology in energy trading. A dynamic grid fee based on electrical network loading is calculated to demonstrate an economic incentive for agents to have flexible load demand as well as to promote local resource utilization. The price volatility of cryptocurrency is addressed by designing a specific energy token for the model.
Chafic BouSaba, Ethan Anderson
One of the most common actions for students post-graduation is requesting a degree validation or an official transcript of grades. Requests for degree validations happen for various reasons such as an employment requirement, a pursuit of a higher degree education, foreign degree accreditation, or even for a personal reason. Those who are requesting the degree validation are usually on a time constraint. Traditional methods of degree validation are often complicated, time consuming, require manpower to maintain, and potentially have security or privacy issues. We present a software application implementing an automatic degree validation system that uses the Ethereum, an open-source, public, blockchain-based distributed computing platform, and that features smart contract functionality. The application is developed using Solidity, a contract-oriented programming language, and is run by the Ethereum Virtual Machine (EVM). This application allows students and universities to automatically verify each other's identity while maintaining transaction validity and referential integrity through a blockchain ledger and maintaining security through PGP key authentication. The university checks the student's request against its own secure mongoDB database. Our application also generates the student's Ehereum wallet using the Truffle development Ethereum network. Truffle generates the student's private and public keys. Our Application pulls the student public key, hashes the last 20 bytes, generates Keccak256 Hash, and stores it on the MongoDB as the student Ethereum Address. To ensure the information's privacy, the blocks of the blockchain are mainly formed of two encrypted fields using the Elliptic Curve Integrated Encryption Scheme (ECIES) library. The first field is encrypted using the student's public key and the second field is encrypted using the third party public field. Third parties, such as employers or other higher education institutions, are able to check its encrypted field of the block using its own private key, once the degree is validated or the transcript is generated. Results of testing show our application to be scalable, secure, have efficient gas costs on the Ethereum network, and minimize human interaction.
Hisham S. Galal, Muhammad ElSheikh, Amr Youssef
No abstract is available for this record.
Vikram Saraph, Maurice Herlihy
We use historical data to estimate the potential benefit of speculative techniques for executing Ethereum smart contracts in parallel. We replay transaction traces of sampled blocks from the Ethereum blockchain over time, using a simple speculative execution engine. In this engine, miners attempt to execute all transactions in a block in parallel, rolling back those that cause data conflicts. Aborted transactions are then executed sequentially. Validators execute the same schedule as miners. \nWe find that our speculative technique yields estimated speed-ups starting at about 8-fold in 2016, declining to about 2-fold at the end of 2017, where speed-up is measured using either gas costs or instruction counts. We also observe that a small set of contracts are responsible for many data conflicts resulting from speculative concurrent execution.
Shangping Wang, Ru Pei, Yaling Zhang
In cloud system, user identity authentication is a key problem. If design defects persist in a cloud user identity authentication scheme, direct risks of sensitive data loss and severe information breach will be incurred. At present, the main problem of cloud user identity management system is that it relies too much on third-party services. Although some third-party-detachment schemes have been proposed in recent years, most of them still rely heavily on cloud server-centered design system. In this paper, a cloud user identity management protocol based on ethereum blockchain was proposed, followed by an establishment of a simple credit management system framework. The new protocol is an improved version of CIDM (Consolidated Identity Management) referred to as EIDM (Ethrerum-based Identity Management) protocol. In the improved protocol, JWT (JSON Web Token) in OAuth 2.0 was used to introduce smart contracts into EIDM protocol, and the credit management system was added to the system so that it can provide a credible identity authentication protocol for cloud users and service providers. The new protocol solves the problem of over-reliance on third parties in the existing identity management system solutions. In the end, an analysis on the security of the new protocol showed that the EIDM protocol proposed in this paper presents more diversified security guarantees relative to the CIDM protocol. The performance evaluation results also indicated that the new protocol demonstrates better practicability and flexibility.
Hanyi Sun, Na Ruan, Hanqing Liu
No abstract is available for this record.
Xinming Wang, Jiahao He, Zhijian Xie, Gansen Zhao · 5 authors
Ethereum smart contracts are programs that can be collectively executed by a network of mutually untrusted nodes. Smart contracts handle and transfer assets of values, offering strong incentives for malicious attacks. Intrusion attacks are a popular type of malicious attacks. In this article, we propose ContractGuard, the first intrusion detection system (IDS) to defend Ethereum smart contracts against such attacks. Like IDSs for conventional programs, ContractGuard detects intrusion attempts as abnormal control flow. However, existing IDS techniques/tools are inapplicable to Ethereum smart contracts due to Ethereum's decentralized nature and its highly restrictive execution environment. To address these issues, we design ContractGuard by embedding it in the contracts to profile context-tagged acyclic paths, and optimizing it under the Ethereum gas-oriented performance model. The main goal is to minimize the overheads, to which the users will be extremely sensitive since the cost needs to be paid upfront in digital concurrency. Empirical investigation using real-life contracts deployed in the Ethereum mainnet shows that on average, ContractGuard only adds to 36.14 percent of the deployment overhead and 28.27 percent of the runtime overhead. Furthermore, we conducted controlled experiments and show that ContractGuard successfully guard against attacks on all real-world vulnerabilities and 83 percent of the seeded vulnerabilities.
Mazin Debe, Khaled Salah, Muhammad Habib ur Rehman, Davor Svetinović
Public fog nodes extend cloud services for the Internet of Things (IoT) clients and smart devices to provide additional computation capabilities, storage space, and reduce latency and response time. The openness and pervasiveness of public fog nodes leads to the requirement of using trust models to ensure reliability, security, privacy, and meet the service-level agreements (SLAs). Conventional trust models for public fog nodes are centrally configured, deployed, and maintained considering security, privacy, and SLA requirements. However, these trust models enforce centralized governance policies across the system which leads towards the single-point-of-failure and single-point-of-compromise over IoT devices' and users' personal data. This paper proposes a decentralized trust model in order to maintain the reputation of publicly available fog nodes. The reputation is maintained considering users' opinions about their past interactions with the public fog nodes. The proposed trust model is designed using public Ethereum blockchain and smart contract technologies in order to enable decentralized trustworthy service provisioning between IoT devices and public fog nodes. The proposed approach is tested and evaluated in terms of security, performance, and cost. The results show that using blockchain for decentralized reputation management could become more advantageous when compared to the existing centralized trust models.