Blockchain Papers

Purathani Praitheeshan, Lei Pan, Xi Zheng, Alireza Jolfaei · 5 authors

No abstract is available for this record.

Hwanjo Heo, Seungwon Shin

Public blockchain records are widely studied in various aspects such as cryptocurrency abuse, anti-money-laundering, and monetary flow of businesses. However, the final blockchain records, usually available from block explorer services or querying locally stored data of blockchain nodes, do not provide abundant and dynamic event logs that are only visible from a live large-scale measurement. In this paper, we collect the network logs of three popular permissionless blockchains, that is, Bitcoin, Ethereum, and EOS. The discrepancy between observed events and the public block data is studied via a noble analysis model provided with the soundness of measurement. We share our key findings including a false universal assumption of previous mining-related studies and the block/transaction arrival characteristics.

Jesús Jaime Moreno Escobar, Oswaldo Morales Matamoros, Ana Lilia Coria Páez, Ricardo Tejeida Padilla

No abstract is available for this record.

Hairil, Niken Dwi Wahyu Cahyani, Hilal H. Nuha

The use of digital currency or cryptocurrency in various virtual transactions is common due to its easiness. Cryptocurrency is a digital currency that is used for virtual transactions on the internet network. The most common types of cryptocurrencies include Litecoin, Ethereum, Monero, Ripple, and Bitcoin. Even though cryptocurrencies have secret codes that are quite complicated and complex that serve to protect and maintain the security of digital currencies, it is possible to be hacked by skilled hackers. Cryptocurrency-related hacking is a type of digital crime that is very harmful or dangerous acts. For example, in recent years, cases of hacking on bitcoin transactions using ransomware have been on the rise. Ransomware is malicious software that secretly infects a victim’s device, and suddenly asks for a ransom to decrypt encrypted data. This type of malware aims to blackmail a victim whose computer is infected with ransomware by asking for a certain amount of money as a ransom. Therefore, a design was built in the form of a ransomware detection system based on available bitcoin heist data so as to minimize hacking attacks against cryptocurrency in the future. The ransomware detection system was built using the backpropagation artificial neural network method using Weka software. The best results in data testing are using the parameter number of hidden layer with 9 neurons; learning rate 0.1; and the number of iterations of 5000 yields an accuracy rate of 97%.

Debendranath Das

Technology has evolved over the years, making our lives easier. It has impacted the healthcare sector, increasing the average life expectancy of human beings. Still, there are gaps that remain unaddressed. There is a lack of transparency in the healthcare system, which results in inherent trust problems between patients and hospitals. In the present day, a patient does not know whether he or she will get the proper treatment from the hospital for the fee charged. A patient can claim reimbursement of the medical bill from any insurance company. However, today there is minimal scope for the Insurance Company to verify the validity of such bills or medical records. A patient can provide fake details to get financial benefits from the insurance company. Again, there are trust issues between the patient (i.e., the insurance claimer) and the insurance company. Blockchain integrated with the smart contract is a well-known disruptive technology that builds trust by providing transparency to the system. In this paper, we propose a blockchain-enabled Secure and Smart HealthCare System. Fairness of all the entities: patient, hospital, or insurance company involved in the system is guaranteed with no one trusting each other. Privacy and security of patients' medical data are ensured as well. We also propose a method for privacy-preserving sharing of aggregated data with the research community for their own purpose. Shared data must not be personally identifiable, i.e, no one can link the acquired data to the identity of any patient or their medical history. We have implemented the prototype in the Ethereum platform and Ropsten test network, and have included the analysis as well.

Emna Mnif, Isabelle Lacombe, Anis Jarboui

Purpose Nowadays, Bitcoin is facing many environmental problems arising from the proof of work based on blockchain. For this reason, Bitcoin Green (BITG) has been created and would solve these issues. The purpose of this paper is to visualize the users’ perception toward BITG through Twitter text analysis. Design/methodology/approach The big data used in this study includes two sources. The first data were extracted from the “Google Trends” engine during the period between 20 September 2015 and 15 September 2020. The second data were extracted from the Twitter application. This research explores the perceived ease of use, the perceived usefulness, the social influence, the perceived control and the user attitudes toward BITG. Therefore, lexicon-based sentiment analysis techniques combined with different dictionaries are built to visualize the drivers of investor attitudes toward the BITG using Twitter text messages. Besides, this study has checked the validity of two main assumptions using the normality (Jarque-Bera) and Kruskal-Wallis rank sum tests capable to conclude whether users mostly perceive BITG as a sustainable technology. Findings This empirical work affords insights into users’ intentions by exploring the drivers of BITG perception. The results show that users positively perceive the use of BITG as a sustainable blockchain. Besides, its usefulness is more appreciated from its ethical and technological characteristics, and its perceived application is mainly based on investment and coin offering use. Similarly, users are mostly showing positive emotions toward BITG. Research limitations/implications Tweets related to “BITG” are not as voluminous as the other cryptocurrencies like Bitcoin and Ethereum, which make it difficult to extract all the characteristics and use cases. Originality/value To the best of the authors’ knowledge, this work is the first one that uses the theory of planned behavior and the theory of acceptance model to explore cognitive factors in understanding investor intentions in adopting BITG.

Hao Liu, Tao Lei, Ruiwen Ji, Lejun Ji · 6 authors

With the popularity of cryptocurrencies such as Bitcoin and Blockchain platforms such as Ethereum, Blockchain has attracted significant attention in many aspects. Blockchain has the characteristics of decentralization, high security, high transparency, high autonomy and non-tampering, which can play a great role in constructing programmable cryptocurrency system and large-scale financial system. Through the analysis of the Blockchain, this paper expounds on the technology of Blockchain, analyzes the existing problems of Blockchain, and introduces the development trend and application scenarios of Blockchain in the future.

Oğuzhan Ersoy, Ziya Alper Genç, Zekeriya Erkin, Mauro Conti

Smart contracts can be used for the fair exchange of digital goods. A smart contract can escrow the exchange where the receiver deposits the payment, and the sender claims it by providing the goods. In the case of misbehavior, the parties provide proof on whether the received goods match the pre-agreed description or not. In general, the description is assumed to be the hash of the goods, and it is publicly known. However, without trusting the description provided by the sender, this assumption is not plausible for the scenarios where the goods are uniquely created for a specific receiver. To overcome the trust issue, sampling-based exchange protocols have been introduced where the parties use a sample of the goods as the description. Yet, the existing sampling-based proposals suffer from high on- and off-chain computational and storage costs. In this paper, we present FairDEx: an efficient sampling- based protocol that is suitable for the exchange of unique goods. Our description protocol allows us to achieve low on- and off-chain costs, which are independent of the size of the goods. The off-chain part of the protocol only utilizes highly efficient algorithms, namely hashing and symmetric key encryption. To illustrate the feasibility of FairDEx, we evaluate a research prototype on the Ethereum test network. Our results show that the cost of running FairDEx is around 0.6M gas for reasonably large sample sets, which is 30% cheaper than the state-of-the-art Ethereum-based proposals.

Lili Chen, Rui Yuan, Yubin Xia

Smart Contracts cannot get external data directly due to the closure and determinacy of blockchain itself, limiting the extensibility of blockchain applications. Oracle is proposed to serve as a data feed to offer authenticated and deterministic external data to smart contracts. However, existing centralized oracles are efficient but vulnerable to targeted attacks and suffering from a single point of failure, while existing decentralized oracles are inefficient. The paper presents a trusted blockchain oracle based on a decentralized Trusted Execution Environment (TEE) network called Tora, which embraces both efficiency and availability. The key of Tora is a hybrid consensus mechanism with the confidential available group selection based on Proof-of-Availability (PoA). We have implemented a prototype of Tora on Ethereum with Intel Software Guard eXtensions (SGX) and evaluated it with a data-fetch use case on different measurements, including gas costs, off-chain execution time, group selection results and throughput. The results show that Tora provides considerable efficiency and scalability.

Jesús Rosa-Bilbao, Juan Boubeta-­Puig

Blockchain is a distributed and secure database that can be applied to all types of transactions. Blockchain technology is growing in popularity because it allows for the development of applications whose information is traceable, immutable, transparent and reliable. Given the advantages that blockchain provides over other traditional systems, in this paper we present a decentralized application, called RectorDApp, for the management of university rector voting in a private, but transparent and immutable way, being able to verify publicly and in real time the election results. RectorDApp, capable of interacting with the Ethereum public blockchain network, was developed using the Truffle framework and the MetaMask software. The results demonstrate that RectorDApp is a highly useful application to address the digital transformation of university rector elections.

Authors unavailable

No abstract is available for this record.

Xiaohui Wang, Peng Liu, Zhixiang Ji

With the release of the electricity sales side, large-scale small-capacity distributed power generation units are connected to the distribution side, forming multi-type market entities such as microgrids, integrated energy systems, and virtual power plants. With the large-scale integration of distributed energy, the energy market under the energy internet is different from a traditional transmission grid. It is currently developing in the direction of diversified entities and commodities, a flat structure, and a flexible and competitive multi-agent market mechanism. In this context, this study analyzes the value of combining blockchain and the electricity market presents the design of a blockchain trading framework for multi-agent cooperation and sharing of the energy internet. The nodes in market transactions are modeled through power system modeling in the physical layer and the transaction consensus strategy in the cyber layer; moreover, the nodes are verified in a modified IEEE 13 testing feeder of a distribution network. A transaction example is demonstrated using the multi-agent cooperation and sharing transaction platform based on the Ethereum private blockchain.

Tomoki Fujitani, Keita Emura, Kazumasa Omote

Maintaining a balance between anonymity and traceability is a fundamental issue in privacy-preserving systems. Isshiki et al. proposed an identity management system based on group signatures in which a service provider anonymously determines whether or not users of the service are legitimate members, and only a bill collector can identify users for the purposes of sending them invoices. It is particularly worth noting that, under the Isshiki system, the service provider is not required to manage personal information such as user lists, which allows the system to outperform other in terms of preserving user privacy and managing personal information leakage risk. It is also noteworthy that the Isshiki system only considers cases in which the bill collector identifies users who have used the service and that, in fact, identified users who ignore invoices can use the service for free. In this paper, we extended the Isshiki system by adding a smart contract-enabled enforcement bill collection functionality. Under this functionality, deposits made by users who do not pay a service fee are automatically transferred to the bill collector. Because of their centralized structure, group signatures are not suitable to blockchain systems, therefore, the proposed system employs accountable ring signatures as building blocks. The privacy-preserving enforced bill collection system is implemented using the accountable ring signature scheme developed by Bootle et al. and Ethereum smart contracts. To reduce the gas costs associated with running smart contracts, the smart contract is not run unless the user ignores an invoice, and basic procedures are run via an off-chain channel. To avoid the use of heavy cryptographic algorithms in carrying out the accountable ring signature scheme for running smart contracts, we employed standard elliptic curve digital signature algorithm (ECDSA) signatures without especially changing the state to be verified in smart contracts.

Ali Alzubaidi, Karan Mitra, Ellis Solaiman

One of the main drivers behind blockchain adoption is a lack of trust among entities serving a common goal, but with different interests. Following the success of Bitcoin, several blockchain platforms have emerged, such as Ethereum and Hyperledger Fabric, to enable conducting distrusted processes in a non-repudiable manner. However, it is not safe to assume the applicability of conventional software design strategies to Blockchain-based solutions. In this paper, we assume an untrusted SLA (service level agreement) relationship between an IoT service provider and its consumer. We adopt Hyperledger Fabric for the purpose of implementing SLA compliance assessment. We design a smart contract that takes blockchain unique features into consideration. The design particularly accounts for the MVCC (multiversion concurrency control) mechanism, which while effective for resolving the double spending problem, causes read-write conflicts when high transmission rates are experienced between the IoT application and the blockchain. Using a fire station event monitoring scenario, we describe our smart contract design and solution for conflicting transactions. We experimentally evaluate our solution and demonstrate clear performance improvements in terms of throughput and latency.

Jinyan Guo, Zigui Jiang, Li Li, Jing Bian

Applications on blockchain are currently limited by the relatively poor performance of the blockchain network such as low TPS, high latency and the resulting high transaction fees. Hence, performance optimization is one crucial problem of blockchain. Focusing on the most prosperous public blockchain Ethereum, we model the on-chain transaction confirmation process with the knowledge of Poisson process and queueing theory, derives the mean transaction-confirmation time, and explores the effect of different transaction fees on latency. We also conduct a numeric simulation of the model, which indicates that the model fits in well with the real world blockchain.

Burcu Sakız, Ayşen Hiç Gencer

Blockchain technology is a disruptive innovation with the potential to replace existing business models that rely on centralized systems and third parties for trust. Even if there are a lot of application areas, blockchain used primarily for cryptocurrencies. Satoshi Nakamoto implemented the first blockchain application and invented the world’s first digital currency which is named as Bitcoin in 2008. Fundementally Bitcoin relies on cryptographic “proof of work” mechanism, digital signatures, and peer to peer distributed networking layer in order to provide a distributed ledger holding transactions. In 2014, a second generation of blockchains allow to program and execute them over distributed networks such as Ethereum project. The code to program any asset stored in blockchain’s peer-to-peer network is called as "smart contract" and smart contracts gives a powerful tool to developers for decentralized applications. There are various types of tokens that anyone can built on top of Ethereum and by combining smart contracts and new tokens, this paved the way of possibility to build a wide range of decentralized projects. One of the disruptive blockchain based innovation impacting intellectual property is called non-fungible-tokens or NFTs firstly introcuced in late 2017 on Ethereum network. This research contends that blockchain and non-fungible tokens (NFTs) which are cryptographically unique, scarce, non-replicable digital assets created through smart contracts and provably digital collectible assets. Our objective is to give NFT taxonomy, review NFT platforms and discuss technical challenges as well as recent advances in tackling the challenges. Moreover, this paper also aims to point out the future directions for NFT technology.

Heidelinde Rameder

Smart Contracts, die auf der Ethereum Blockchain eingesetzt werden, halten Vermögenswerte im Wert von Milliarden von USD. Ethereum ist derzeit die am meisten genutzte Plattform für Smart Contracts. Gemessen an der Marktkapitalisierung ist Ethereum nach Bitcoin die zweitgrößte Blockchain mit einem stetig wachsenden Marktanteil. Da Smart Contracts nach der Bereitstellung nicht mehr geändert werden können, ist es von entscheidender Bedeutung, dass der Code auf potenzielle Schwachstellen überprüft wird, die erhebliche finanzielle Verluste verursachen und das Vertrauen beschädigen können. Zu diesem Zweck wurden zahlreiche Tools entwickelt, und es wird immer mehr Literatur über Schwachstellen und Erkennungsmethoden zu diesem Thema veröffentlicht. Regelmäßige Literaturanalysen sind unerlässlich, um mit der raschen Entwicklung auf diesem Gebiet Schritt halten zu können. Diese Arbeit präsentiert eine systematische Literatur- und Toolanalyse, die einen strukturierten, umfassenden Überblick über den aktuellen Stand der Technik von Tools, Smart Contract Schwachstellen und Erkennungsmethoden bietet. Die Einhaltung und Protokollierung einer präzisen Evaluierungsstrategie, Such- und Relevanzprüfungen gewährleisten umfassende und reproduzierbare Ergebnisse. Nach Bereinigung der Referenzen, Entfernung von Duplikaten sowie Anwendung von definierten Ein- und Ausschlusskriterien, führte die initiale Literatursuche zu einer ersten Identifikation von 303 Publikationen. Auf Basis einer Qualitätsbewertung auf Grundlage intrinsischer und kontextbezogener Datenqualitätsmetriken wurden schließlich 149 Primärstudien, 38 Surveys und 8 systematische Literaturanalysen für die Datenextraktion ausgewählt. Die Synthese beinhaltet eine umfassende Klassifizierung von Smart Contract Schwachstellen, eine neue Taxonomie der Eigenschaften und verwendeten Methoden von Analysetools sowie einen Überblick über Tools, einschließlich eines strukturierten Vergleichs auf Grundlage der Taxonomie. Schließlich wird eine konsolidierte Sammlung veröffentlichter und verfügbarer Benchmark-Datensätze bereitgestellt.

Xiaoping Zhou, Peng Li, Yulong Zeng, Xuepeng Fan · 6 authors

Blockchain-based voting, including liquid voting, has been extensively studied in recent years. However, it remains challenging to implement liquid voting on blockchain using Ethereum smart contract. The challenge comes from the gas limit, which is that the number of instructions for processing a ballot cannot exceed a certain amount. This restricts the application scenario with respect to algorithms whose time complexity is linear to the number of voters, i.e., O(n). As the blockchain technology can well share and reuse the resources, we study a model of liquid voting on blockchain and propose a fast algorithm, named Flash, to eliminate the restriction. The key idea behind our algorithm is to shift some on-chain process to off-chain. In detail, we first construct a Merkle tree off-chain which contains all voters' properties. Second, we use Merkle proof and interval tree to process each ballot with O(log n) on-chain time complexity. Theoretically, the algorithm can support up to 21000 voters with respect to the current gas limit on Ethereum. Experimentally, the result implies that the consumed gas fee remains at a very low level when the number of voters increases. This means our algorithm makes liquid voting on blockchain practical even for massive voters.

Xudong Zhu, Hui Li

Deep learning has achieved the high-accuracy of state-of-the-art algorithms in long-standing AI tasks. Due to the obvious privacy issues of deep learning, Google proposes Federal Deep Learning (FDL), in which distributed participants only upload local gradients and and a centralized server updates parameters based on the collected gradients. But few users are willing to participate in federated learning due to the lack of contribution evaluation and reward mechanisms. So a decentralized federated deep learning, called DFDL, has been proposed by introducing blockchain to form an effective incentive mechanism for participants. However, DFDL still faces serious privacy issues as blockchain does not guarantee the privacy of training data and model. In this paper, in order to address the aforementioned issues, we propose a new Privacy-preserving DFDL scheme, called PDFDL. With PDFDL, parties can securely learn a global model with their local gradients in the assistance of blockchain, and the parties’ sensitive data and the global model are well protected. Specifically, with a secure multi-party aggregation computing, all local gradients are encrypted by their owners before being sent to the smart contract, and can be directly aggregated without decryption. Detailed security analysis shows that PDFDL can resist various known security threats. Moreover, we give an implementation prototype by integrating deep learning module with a Blockchain development platform (Ethereum V1.6.4). We demonstrate the encryption performance and the training accuracy of our PDFDL on benchmark datasets.

윤영진

Recently, digital artworks based on NFT (Non-Fungible Token) have often been sold at high prices, drawing a lot of attention. It is time to carefully examine whether NFT is an important technological means to bring new life to the digital art trade and copyright market, or is it just a mirage caused by some fanatics and irrational overheating. Therefore, this study examines the impact of NFT on the IP industry. To help understand NFT, the technologies underlying the creation and transaction of NFT, such as Blockchain, Bitcoin, and Ethereum, are explored. And based on this understanding, what NFT is and why it is creating a craze, the concept, characteristics, creation and transaction method of NFT, utilization and its limitations are reviewed. Transactions through NFT are expected to cause various confusion in the area of intellectual property law. In conjunction with digital transformation, it will accelerate the ‘digitization of assets’ and deepen the separation of ownership and copyright over digital assets. The conflict between ownership and copyright is expected to develop into the question of whether the doctrine of rights exhaustion is applied to digital works and whether the exercise of copyright can be restricted. Also, due to the decentralized nature of NFT, the role of intermediaries who mediate creators and consumers will be reduced, and it seems necessary to discuss whether it is appropriate to apply the current online service provider exemption scheme to the responsibilities of NFT trading site. In addition, in the patent and trademark system, it is expected that a problem will arise whether transactions through NFTs can be subsumed into ‘practice’ under the Patent Act or ‘use’ under the Trademark Act. And as NFT is used as a technical means to authenticate the ownership of digital assets, it is expected to become a catalyst for making the fandom industry and game industry larger. It is time for regulators and lawyers to take creative approaches and new perspectives to become laws and systems that play a role in helping science and technology can be used for humans, not as a means of hindering development and innovation.

Pengting Du, Yingjian Liu, Yue Li, Haoyu Yin · 5 authors

As the underlying technology of cryptocurrency, blockchain is characterized by decentralization and immutability. It is considered as a new generation of disruptive technology. However, the underlying storage of blockchain only provides limited support for data query. This limits the utility of blockchain technology. To improve the efficiency of access to blockchain data, we design EtherH based on Ethereum, the most representative open blockchain system. EtherH is a hybrid index that can provide Single-V query and Range query on Ethereum blockchain. To make the index build more specific, EtherH supports elastic data building. A portion of the blockchain data is selected for index building. We connect the client to the Rinkeby network to obtain block data and conduct extensive experiments. Experimental results prove that EtherH performs well in both data insertion and data query.

Hrithik Gaikwad, Nevil D'Souza, Rajkumar Gupta, Amiya Kumar Tripathy

Millions of students complete their education each year and go on to do higher studies or a corporate job. In this case student credentials are verified through a lengthy document verification process. This results in significant overhead as documents are transferred between institutions for verification. There is a need for an automated credential verification system which can reduce the time required for the document verification process. Blockchain Technology can be used to reduce overhead and reduce the time taken for document verification from days to mere seconds. In this work, an attempt has been made to develop a Blockchain-based verification system for academic certificates. With the advent of public Blockchain like Ethereum, DApps (Decentralized Applications) and Smart contracts, scalable and cost effective solutions can be implemented to reduce overhead and make document verification a seamless process. The proposed solution consists of a web app which will have a front-end for registering and requesting verification, along with a backend which will have two modules: An OCR module to extract details from certificates and a Blockchain module to send and verify data stored in the Blockchain.

M. Erik Gunawan, Achmad Herlanto Anggono

Safe-haven assets conserve their value or grow against another asset or portfolioduring market turmoil. Indonesian stock market, represented by the Jakarta composite index (JKSE), plunged in price because of COVID-19, pushing investors to look for safe-havens. The cryptocurrency began to be perceived as a store of value as indicated by the transaction volume increase; hence it was expected to be a safe haven asset. However, cryptocurrency’s high price volatility cast doubts on its store of value effectiveness, prompting inspection for its safe haven property as well. This research aimed to predict the assets' risk and return plus investigate whether cryptocurrency is safe haven assets against the Indonesian stock market during COVID- 19. Daily closing prices of JKSE, Bitcoin, Ethereum, Litecoin, and Ripple were used, then the GARCH model was implemented in the forecasting. DCC-GARCH model, followed by dummy variable regression, will be applied to the return data to evaluate the safe haven property. The prediction projected Bitcoin as the most profitable asset andRipple as the riskiest. The analysis and robustness test suggested that none of these cryptocurrencies were safe haven assets during the whole observation. This indicates that investors who intend to seek safe haven investments were advised against investing in these cryptocurrencies.

Nitima Malsa, Vaibhav Vyas, Jyoti Gautam

No abstract is available for this record.