Follow blockchain research across journals, conferences, and preprint repositories.
13,493 results · page 413 of 563
Gianluca Lax, Antonia Russo, Lara Saidia Fascí
No abstract is available for this record.
Ammar Battah, Youssef Iraqi, Ernesto Damiani
Reputation expresses the beliefs or opinions about someone or something that are held by an individual or by a community. Reputation Management Systems (RMSs) handle representation, computation, and storage of reputation in some quantitative form, suitable for grounding trust relations among parties. Quantifying reputation is important in situations, like online service provision, which involve interaction between parties who do not know (and potentially distrust) each other. The basic idea is to let parties rate each other. When a party is considered for interaction, its ratings can be aggregated in order to derive a score for deciding whether to trust it or not. While much valuable research work has been done on reputation-based trust schemes, the problem of establishing collective trust in the reputation management system itself has never been fully solved. Recently, several researchers have put forward the idea of using Distributed Ledger Technology (DLT) as the foundation for implementing trustworthy RMSs. The purpose of this paper is to identify some critical problems that arise when DLTs are used in order to manage evidence about previous interaction and compute reputations. The paper proposes some practical solutions and describes methods to deploy them on top of standard DLT of the Ethereum family.
Hyoungsung Kim, Jaehyuk Jang, Sangjun Park, Heung-No Lee
The error-correction code based proof-of-work (ECCPoW) algorithm is based on a low-density parity-check (LDPC) code. The ECCPoW is possible to impair ASIC with its time-varying capability of the parameters of LDPC code. Previous researches on the ECCPoW algorithm have presented its theory and implementation on Bitcoin. But they do not discuss how stable the block generation time is. A finite mean block generation time (BGT) and none heavy-tail BGT distribution are the ones of the focus in this study. In the ECCPoW algorithm, BGT may show a long-tailed distribution due to time-varying cryptographic puzzles. Thus, it is of interest to see if the BGT distribution is not heavy-tailed and if it shows a finite mean. If the distribution is heavy-tailed, then confirmation of a transaction cannot be guaranteed. We present implementation, simulation, and validation of ECCPoW Ethereum. In implementation, we explain how the ECCPoW algorithm is integrated into Ethereum 1.0 as a new consensus algorithm. In the simulation, we perform a multinode simulation to show that the ECCPoW Ethereum works well with automatic difficulty change. In the validation, we present the statistical results of the two-sample Anderson-Darling test to show that the distribution of BGT satisfies the necessary condition of the exponential distribution. Our implementation is downloadable at https://github.com/cryptoecc/ETH-ECC.
Qinwei Lin, Chao Li, Xifeng Zhao, Xianhai Chen
Decentralization has been widely acknowledged as a core virtue of blockchains. However, in the past, there have been few measurement studies on measuring and comparing the actual level of decentralization between existing blockchains using multiple metrics and granularities. This paper presents a new comparison study of the degree of decentralization in Bitcoin and Ethereum, the two most prominent blockchains, with various decentralization metrics and different granularities within the time dimension. Specifically, we measure the degree of decentralization in the two blockchains during 2019 by computing the distribution of mining power with three metrics (Gini coefficient, Shannon entropy, and Nakamoto coefficient) as well as three granularities (days, weeks, and months). Our measurement results with different metrics and granularities reveal the same trend that, compared with each other, the degree of decentralization in Bitcoin is higher, while the degree of decentralization in Ethereum is more stable. To obtain the cross-interval information missed in the fixed window based measurements, we propose the sliding window based measurement approach. The corresponding results demonstrate that the use of sliding windows could reveal additional cross-interval information overlooked by the fixed window based measurements, thus enhancing the effectiveness of measuring decentralization in terms of continuous trends and abnormal situations. We believe that the methodologies and findings in this paper can facilitate future studies of decentralization in blockchains.
Nur Widiyasono, Aldy Putra Aldya, Rifan Renanda Ardhian
“Miners” bekerja untuk memecahkan masalah matematika yang kompleks untuk menghasilkan pendapatan dalam bentuk mata uang digital, seperti Bitcoin, Ethereum, Monero, dan lainnya. Proses mining ini membutuhkan perangkat keras yang serius dan sumber daya CPU yang signifikan untuk menciptakan cryptocurrency. Cryptojacking salah satu alat penambangan mata uang digital secara illegal. Cryptojacking dapat memberikan return yang lebih substansial bagi penyerang.Cryptominer jenis ini tidak terlalu membahayakan secara langsung kepada para korbannya, tetapi hanya saja menggunakan akses illegal ke komputer korban dan menggunakan sumber daya korban untuk menambang crypto. Metode yang digunakan adalah dynamic analysis. Dinamic Analysis adalah mencari informasi atau sampel mengenai malware dengan cara menjalankannya. Dengan metode ini dapat terlihat “perilaku” dari malware tersebut sehingga selanjutnya dapat dianalisa dampak yang terjadi. Pengujian malware ini dilakukan dengan 2 cara yaitu pengujian pertama dilakukan dengan javascript injection pada jaringan lokal yang sama dengan korban yaitu wifi publik dan pengujian kedua dengan mengakses website yang terindikasi skrip cryptojacking. Berdasarkan hasil analisis menggunakan dynamic analysis dimana cryptojacking dapat menginfeksi langsung ke website atau melalui jaringan local dengan javascript injection, jika website telah terinfeksi cryptojacking maka pengunjung dari website tersebut akan menjadi korban dan terjadi penambangan tersembunyi yang akan memakan sumber daya korban dan cryptojacking operator dalang dibalik website yang terinfeksi akan menerima keuntungan dalam bentuk mata uang digital dari hasil cryptojacking ini
Tae-Young Kim, Hyung-Jong Kim
No abstract is available for this record.
Liang Tan, Huan Xiao, Keping Yu, Moayad Aloqaily · 5 authors
No abstract is available for this record.
Dushyant Behl, Palanivel Kodeswaran, Venkatraman Ramakrishna, Sayandeep Sen · 5 authors
Private blockchain networks are used by enterprises to manage decentralized processes without trusted mediators and without exposing their assets publicly on an open network like Ethereum. Yet external parties that cannot join such networks may have a compelling need to be informed about certain data items on their shared ledgers along with certifications of data authenticity; e.g., a mortgage bank may need to know about the sale of a mortgaged property from a network managing property deeds. These parties are willing to compensate the networks in exchange for privately sharing information with proof of authenticity and authorization for external use. We have devised a novel and cryptographically secure protocol to effect a fair exchange between rational network members and information recipients using a public blockchain and atomic swap techniques. Using our protocol, any member of a private blockchain can atomically reveal private blockchain data with proofs in exchange for a monetary reward to an external party if and only if the external party is a valid recipient. The protocol preserves confidentiality of data for the recipient, and in addition, allows it to mount a challenge if the data turns out to be inauthentic. We also formally analyze the security and privacy of this protocol, which can be used in a wide array of practical scenarios
Hongyu Song, Nafei Zhu, Ruixin Xue, Jingsha He · 6 authors
No abstract is available for this record.
Sam M. Werner, Daniel Pérez, Lewis Gudgeon, Ariah Klages‐Mundt · 6 authors
Decentralized Finance (DeFi), a blockchain powered peer-to-peer financial system, is mushrooming. Two years ago the total value locked in DeFi systems was approximately 700m USD, now, as of April 2022, it stands at around 150bn USD. The frenetic evolution of the ecosystem has created challenges in understanding the basic principles of these systems and their security risks. In this Systematization of Knowledge (SoK) we delineate the DeFi ecosystem along the following axes: its primitives, its operational protocol types and its security. We provide a distinction between technical security, which has a healthy literature, and economic security, which is largely unexplored, connecting the latter with new models and thereby synthesizing insights from computer science, economics and finance. Finally, we outline the open research challenges in the ecosystem across these security types.
Matheus Leal, Flávia Pisani, Markus Endler
Abstract Several applications can benefit from recording information about the places a mobile entity visits and the length of time it spends there (e.g., shoppers, employees, buses, portable equipment, autonomous robots). This paper presents our approach to recording spatio-temporal presence information in a secure and inviolable way using a Distributed Ledger Technology. We implemented this solution as a middleware service that uses Complex Event Processing on smartphones to record beacon-smartphone proximity data in a blockchain efficiently. We have built upon the previous version of our service to include access control to the stored information. We analyzed the impact of this addition on the service’s performance and observed that it introduced very little overhead while significantly increasing user privacy. Furthermore, we compared the effect of using different blockchain technologies on overall service performance and characterized scenarios where using either IoTeX or Ethereum can be suitable for this type of application.
Yash Muchhala, Harshit Singhania, Sahil Sheth, Kailas Devadkar
Smart Contracts based cryptocurrencies such as Ethereum are becoming increasingly popular in various domains: but with this increase in popularity comes a significant decrease in throughput and efficiency. Smart Contracts are executed by every miner in the system serially without any parallelism, both inter and intra-Smart Contracts. Such a serial execution inhibits the scalability required to obtain extremely high throughput pertaining to computationally intensive tasks deployed with such Smart Contracts. While significant advancements have been made in the field of concurrency, from GPU architectures that enable massively parallel computation to tools such as MapRe-duce that distributed computing to several nodes connected in the system to achieve higher performance in distributed systems, none are incorporated in blockchain-based distributed computing. The team proposes a novel blockchain that allows public nodes in a permission-independent blockchain to deploy and run Smart Contracts that provide concurrency-related functionalities within the Smart Contract framework. In this paper, the researchers present “ConCurrency,” a blockchain network capable of handling big data-based computations. The technique is based on currently used distributed system paradigms, such as MapReduce, while also allowing for fundamental parallelly computable problems. Concurrency is achieved using a sharding protocol incorporated with consensus mechanisms to ensure high scalability, high reliability, and better efficiency. A detailed methodology and a comprehensive analysis of the proposed blockchain further indicate a significant increase in throughput for parallelly computable tasks, as detailed in this paper.
Priyank Hajela, Ambika Pawar, Shraddha Phansalkar
This chapter aims to study the research gaps in the field of healthcare privacy using blockchain and develop an interoperable and secure solution using blockchain technology. It discusses some of the state-of-art privacy-preserving proof of concepts and applications related to the healthcare industry. The chapter provides a brief overview of the related work done in the field of the healthcare industry. Abdullah Al Omar et al. have used the Ethereum blockchain platform for their solution which is a public blockchain platform and requires generating or mining hashes which involves a high computational cost as well as vulnerability in terms of the hash key. The blockchain project in the healthcare scenario will be called I Treat You, which refers to a treatment (business) transaction between bilateral parties, that is, the doctor and patient in Corda. The chapter shows that the doctor–patient treatment interaction can be made private using a permission-based and bilateral ledger-based blockchain platform like Corda.
Rong Li, Sufang Li, Di Yuan, Huiming Zhu
No abstract is available for this record.
Mengjie Chen, Daoyuan Wu, Yi Xiao, Jianliang Xu
Mobile app markets are emerging with the popularity of smartphones. However, they fall short in several aspects, including no transparent app listing, no world-wide app access, and even insecure app downloading. To address these problems, we propose a novel blockchain-based gateway, AGChain, to bridge end users and app markets so that existing app markets could still provide services while users enjoy permanent, distributed, and secure app delegation from AGChain. To this end, we identify two previously under-estimated challenges and propose mechanisms to significantly reduce gas costs in our smart contract and make IPFS (Inter-planetary File System) based file storage really distributed. We also address three AGChain-specific system challenges to make it secure and sustainable. We have implemented an AGChain prototype (https://www.agchain.ltd/) on Ethereum. The evaluation shows that it achieves security and decentralization with minimal gas costs and reasonable performance.
Mengjie Chen, Yi Xiao, Daoyuan Wu, Jianliang Xu · 6 authors
The popularity of smartphones has led to the growth of mobile app markets, creating a need for enhanced transparency, global access, and secure downloading. This paper introduces AGChain, a blockchain-based gateway that enables trustworthy app delegation within existing markets. AGChain ensures that markets can continue providing services while users benefit from permanent, distributed, and secure app delegation. During its development, we address two key challenges: significantly reducing smart contract gas costs and enabling fully distributed IPFS-based file storage. Additionally, we tackle three system issues related to security and sustainability. We have implemented a prototype of AGChain on Ethereum and Polygon blockchains, achieving effective security and decentralization with a minimal gas cost of around 0.002 USD per app upload (no cost for app download). The system also exhibits reasonable performance with an average overhead of 12%.
Sissi Xiaoxiao Wu, Zixian Wu, Shihui Chen, Gangqiang Li · 5 authors
In this work, we consider community detection in blockchain networks. We specifically take the Bitcoin network and Ethereum network as two examples, where community detection serves in different ways. For the Bitcoin network, we modify the traditional community detection method and apply it to the transaction social network to cluster users with similar characteristics. For the Ethereum network, on the other hand, we define a bipartite social graph based on the smart contract transactions. A novel community detection algorithm which is designed for low-rank signals on graph can help find users' communities based on user-token subscription. Based on these results, two strategies are devised to deliver on-chain advertisements to those users in the same community. We implement the proposed algorithms on real data. By adopting the modified clustering algorithm, the community results in the Bitcoin network is basically consistent with the ground-truth of betting site community which has been announced to the public. At the meanwhile, we run the proposed strategy on real Ethereum data, visualize the results and implement an advertisement delivery on the Ropsten test net.
Mahsa Moosavi, Jeremy Clark
Financial regulators have long-standing concerns about fully decentralized exchanges that run 'on-chain' without any obvious regulatory hooks. The popularity of Uniswap, an automated market makers (AMM), made these concerns a reality. AMMs implement a lightweight dealer-based trading system, but they are unlike anything on Wall Street, require fees intrinsically, and are susceptible to front-running attacks. This leaves the following research questions we address in this paper: (1) are conventional (i.e., order books), secure (i.e., resistant to front-running and price manipulation) and fully decentralized exchanges feasible on a public blockchain like Ethereum, (2) what is the performance profile, and (3) how much do Layer 2 techniques (e.g., Arbitrum) increase performance? To answer these questions, we implement, benchmark, and experiment with an Ethereum-based call market exchange called Lissy. We confirm the functionality is too heavy for Ethereum today (you cannot expect to exceed a few hundred trade executions per block) but show it scales dramatically (99.88% gas cost reduction) on Arbitrum.
Rongjian Lan, Ganesha Upadhyaya, Stephen Tse, Mahdi Zamani
With the rise of digital currency systems that rely on blockchain to ensure ledger security, the ability to perform cross-chain transactions is becoming a crucial interoperability requirement. Such transactions allow not only funds to be transferred from one blockchain to another (as done in atomic swaps), but also a blockchain to verify the inclusion of any event on another blockchain. Cross-chain bridges are protocols that allow on-chain exchange of cryptocurrencies, on-chain transfer of assets to sidechains, and cross-shard verification of events in sharded blockchains, many of which rely on Byzantine fault tolerance (BFT) for scalability. Unfortunately, existing bridge protocols that can transfer funds from a BFT blockchain incur significant computation overhead on the destination blockchain, resulting in a high gas cost for smart contract verification of events. In this paper, we propose Horizon, a gas-efficient, cross-chain bridge protocol to transfer assets from a BFT blockchain to another blockchain (e.g., Ethereum) that supports basic smart contract execution.
Nazrul Islam, Yorgos Marinakis, Sterling Olson, Reilly White · 5 authors
Blockchain technologies are at the heart of digital innovation and are a harbinger of Industry 4.0. Consequently, popular press and academic researchers alike have focused on its importance. Yet blockchain technologies’ most promising efforts, cryptocurrency and smart contracts, are underpinned by blockchain mining. The blockchain mining service is undergoing change, cryptocurrencies like Ethereum and others are nearing the end of their minting. Smart contracts are in their infancy. The financial impetus for providing the mining service has changed. Here, we add to the literature through a deep financial analysis of blockchain mining regarding its long-term financial viability. Our methods include a financial cost analysis and an analysis of the financial viability of cryptocurrency through focus on Ethereum. It is found that blockchain miners, despite initial profitability, cannot maintain sustainable financial viability without substantial fees. This article is important to those academics who focus on understanding how service technologies and products underpin Industry 4.0. Finally, this article contributes to the practitioners’ decision-making process to embrace blockchain mining as a technological entrepreneur.
Goran Sladić, Branko Milosavljević, Siniša Nikolić, Dubravka Sladić · 5 authors
The origins of digital money and blockchain technology goes back to the 1980s, but in the last decade, the blockchain technology gained large popularity in the financial sector with the appearance of cryptocurrencies such as Bitcoin. However, recently, many other fields of application have been recognized, particularly with the development of smart contracts. Among them is the possible application of blockchain technology in the domain of land administration, mostly as a tool for transparency in the developing countries and means to fight corruption. However, developed countries also find interest in launching pilot projects to test their applicability in land administration domain for reasons such as to increase the speed and reduce costs of the real property transactions through a more secure environment. In this paper, we analyse how transactions are handled in Serbian land administration and how this process may be supported by modern ledger technologies such as blockchain. In order to analyse how blockchain could be implemented to support transactions in land information systems (LIS), it is necessary to understand cadastral processes and transactions in LIS, as well as legislative and organizational aspects of LIS. Transactions in cadastre comprise many actors and utilize both alphanumeric (descriptive or legal) data and geospatial data about property boundaries on the cadastral map. Based on the determined requirements for the blockchain-based LIS, we propose a system architecture for its implementation. Such a system keeps track of transactions in LIS in an immutable and tamper-proof manner to increase the security of the system and consequently increase the speed of transactions, efficiency, and data integrity without a significant impact on the existing laws and regulations. The system is anticipated as a permissioned public blockchain implemented on top of the Ethereum network.
Christof Ferreira Torres, Antonio Ken Iannillo, Arthur Gervais, Radu State
In recent years, Ethereum gained tremendously in popularity, growing from a\ndaily transaction average of 10K in January 2016 to an average of 500K in\nJanuary 2020. Similarly, smart contracts began to carry more value, making them\nappealing targets for attackers. As a result, they started to become victims of\nattacks, costing millions of dollars. In response to these attacks, both\nacademia and industry proposed a plethora of tools to scan smart contracts for\nvulnerabilities before deploying them on the blockchain. However, most of these\ntools solely focus on detecting vulnerabilities and not attacks, let alone\nquantifying or tracing the number of stolen assets. In this paper, we present\nHorus, a framework that empowers the automated detection and investigation of\nsmart contract attacks based on logic-driven and graph-driven analysis of\ntransactions. Horus provides quick means to quantify and trace the flow of\nstolen assets across the Ethereum blockchain. We perform a large-scale analysis\nof all the smart contracts deployed on Ethereum until May 2020. We identified\n1,888 attacked smart contracts and 8,095 adversarial transactions in the wild.\nOur investigation shows that the number of attacks did not necessarily decrease\nover the past few years, but for some vulnerabilities remained constant.\nFinally, we also demonstrate the practicality of our framework via an in-depth\nanalysis on the recent Uniswap and Lendf.me attacks.\n
Ernie Teo
No abstract is available for this record.
Orestis Alpos, Christian Cachin, Giorgia Azzurra Marson, Luca Zanolini
Modern blockchains support a variety of distributed applications beyond cryptocurrencies, including smart contracts -- which let users execute arbitrary code in a distributed and decentralized fashion. Regardless of their intended application, blockchain platforms implicitly assume consensus for the correct execution of a smart contract, thus requiring that all transactions are totally ordered. It was only recently recognized that consensus is not necessary to prevent double-spending in a cryptocurrency (Guerraoui et al., PODC'19), contrary to common belief. This result suggests that current implementations may be sacrificing efficiency and scalability because they synchronize transactions much more tightly than actually needed. In this work, we study the synchronization requirements of Ethereum's ERC20 token contract, one of the most widely adopted smart contacts. Namely, we model a smart-contract token as a concurrent object and analyze its consensus number as a measure of synchronization power. We show that the richer set of methods supported by ERC20 tokens, compared to standard cryptocurrencies, results in strictly stronger synchronization requirements. More surprisingly, the synchronization power of ERC20 tokens depends on the object's state and can thus be modified by method invocations. To prove this result, we develop a dedicated framework to express how the object's state affects the needed synchronization level. Our findings indicate that ERC20 tokens, as well as other token standards, are more powerful and versatile than plain cryptocurrencies, and are subject to dynamic requirements. Developing specific synchronization protocols that exploit these dynamic requirements will pave the way towards more robust and scalable blockchain platforms.