Blockchain Papers

Youssef Faqir-Rhazoui, Javier Arroyo, Samer Hassan

No abstract is available for this record.

Juhar Abdella, Zahir Tari, Adnan Anwar, Abdun Naser Mahmood · 5 authors

Several recent studies have suggested Blockchain for Peer-to-Peer energy trading (P2P-ET) to achieve better security, privacy and fast payment settlement. Most of them however rely on either public Blockchains (which have low performance) or permissioned blockchains (which have low decentralization level and do not provide byzantine fault tolerance). Moreover, these solutions have limitations when capturing the business model of existing energy trading systems. This article proposes a Unified permissioned blockchain-based P2P-ET Architecture (UBETA) that integrates three different types of energy markets and provides a unified energy trading and payment settlement model. The UBETA system is based on an enterprise Ethereum Blockchain, known as Hyperledger Besu, and Istanbul Byzantine Fault Tolerance (IBFT) consensus algorithm. We compared the performance of the proposed IBFT-based system with three existing systems (i.e., Ethereum Clique, Ethereum Proof of Work and Hyperledger Fabric's Raft) using specific performance metrics (i.e., read/write transaction latency, read/write transaction throughput and fail rate). The experiments were carried out on a network size of up to 60 nodes and a real energy trading data set from the Western Australian energy market was used. The experiment results indicate that the IBFT-based system has 15x lower latency and nearly 2x throughput compared to existing Proof of Work based P2P-ET solutions. Moreover, the system provides better scalability and success rate than existing Raft based P2P-ET systems: the fail rate of the IBFT-based system only increased by 11% while that of Raft increased by 20% when increasing the number of nodes from 20 to 60. In addition, the proposed unified energy trading model provides lower latency and reduces the number of blockchain transactions compared to the non-unified counterpart.

Syed Jawad Hussain Shahzad, Faruk Balli, Muhammad Abubakr Naeem, Mudassar Hasan · 5 authors

No abstract is available for this record.

Michael Neuder, Daniel J. Moroz, Rithvik Rao, David C. Parkes

We outline two dishonest strategies that can be cheaply executed on the Ethereum 2.0 beacon chain, even by validators holding less than one-third of the total stake: malicious chain reorganizations ("reorgs") and finality delays. In a malicious reorg, an attacker withholds their blocks and attestations before releasing them at an opportune time in order to force a chain reorganization, which they can take advantage of by double-spending or front-running transactions. To execute a finality delay an attacker uses delayed block releases and withholding of attestations to increase the mean and variance of the time it takes blocks to become finalized. This impacts the efficiency and predictability of the system. We provide a probabilistic and cost analysis for each of these attacks, considering a validator with 30% of the total stake.

Runhua Xu, Chao Li, James Joshi

Increasingly, information systems rely on computational, storage, and network resources deployed in third-party facilities such as cloud centers and edge nodes. Such an approach further exacerbates cybersecurity concerns constantly raised by numerous incidents of security and privacy attacks resulting in data leakage and identity theft, among others. These have, in turn, forced the creation of stricter security and privacy-related regulations and have eroded the trust in cyberspace. In particular, security-related services and infrastructures, such as Certificate Authorities (CAs) that provide digital certificate services and Third-Party Authorities (TPAs) that provide cryptographic key services, are critical components for establishing trust in crypto-based privacy-preserving applications and services. To address such trust issues, various transparency frameworks and approaches have been recently proposed in the literature. This paper proposes TAB framework that provides transparency and trustworthiness of third-party authority and third-party facilities using blockchain techniques for emerging crypto-based privacy-preserving applications. TAB employs the Ethereum blockchain as the underlying public ledger and also includes a novel smart contract to automate accountability with an incentive mechanism that motivates users to participate in auditing, and punishes unintentional or malicious behaviors. We implement TAB and show through experimental evaluation in the Ethereum official test network, Rinkeby, that the framework is efficient. We also formally show the security guarantee provided by TAB, and analyze the privacy guarantee and trustworthiness it provides.

Jing‐Zhi Huang, Zhijian Huang, Li Xu

This paper studies the dynamics of cryptocurrency volatility using a stochastic volatility model with simultaneous and correlated jumps in returns and volatility. We estimate the model using an efficient sequential learning algorithm that allows for learning about multiple unknown model parameters simultaneously, with daily data on four popular cryptocurrencies. We find that these cryptocurrencies have quite different volatility dynamics. In particular, they exhibit different return-volatility relationships: While Ethereum and Litecoin show a negative relationship, Chainlink displays a positive one and interestingly, Bitcoin’s one changes from negative to positive in June 2016. We also provide evidence that the sequential learning algorithm helps better detect large jumps in the cryptocurrency market in real time. Overall, incorporating volatility jumps helps better capture the dynamic behavior of highly volatile cryptocurrencies.

Qin Wang, Rujia Li

A large number of consensus algorithms have been proposed. However, the requirement of strict consistency limits their wide adoption, especially in high-performance required systems. In this paper, we propose a weak consensus algorithm that only maintains the consistency of relative positions between the messages. We apply this consensus algorithm to construct a high-performance blockchain system, called \textit{Sphinx}. We implement the system with 32k+ lines of code including all components like consensus/P2P/ledger/etc. The evaluations show that Sphinx can reach a peak throughput of 43k TPS (with 8 full nodes), which is significantly faster than current blockchain systems such as Ethereum given the same experimental environment. To the best of our knowledge, we present the first weak consensus algorithm with a fully implemented blockchain system.

Nakhoon Choi, Heeyoul Kim

With the increase of smart factories and smart cities following the recent 4th industrial revolution, internal user authentication and authorization have become an important issue. The user authentication model using the server-client structure has a problem of forgery of the access history caused by the log manipulation of the administrator and unclearness of the responsibility. In addition, users must independently manage the authentication method for each service authentication. In this paper, to solve the above problem, the researchers propose an integrated ID model based on a hybrid blockchain. The proposed model is implemented as two layers of Ethereum and Hyperledger Fabric: the former layer is responsible for integrated authentication, and the latter layer is responsible for access control. The physical pass or application for user authentication and authorization are integrated to one ID through the proposed model. In addition, the decentralized blockchain ensures the integrity and transparency of the stored access history, and it also provides non-repudiation of authority and access history.

D. Srivatsa, N. S. Jai Aakash, S. Sahisnu, Priyanka Kumar

Abstract The supply chain management industry is struggling with inadequate resources for efficient authenticity verification. Blockchain technology and smart contracts can overcome such conventional limitations to authenticate products in an easy, economical and secure manner. Decentralized and immutable blockchain systems allow product tracking to its origin.In this paper we have proposed and implemented a system for product authentication using blockchain technology based on ethereum platform by making use of smart contracts. We have analysed the existing centralized system and the need to shift from the existing centralized system to a decentralized blockchain based ledger technology. The use of blockchain technology in supply chain technology has reduced the complexity in product authentication by making the entire history of the product available from its production stage till it reaches the customer.

Χρήστος Δαβιλάς

Με την παρούσα μεταπτυχιακή εργασία θα μελετήσουμε τις βασικές έννοιες του blockchain, των smart contracts καθώς και την ασφάλεια των τελευταίων. Tα smart contracts καταλαμβάνουν πολλούς τομείς της βιομηχανίας προκειμένου να αυτοματοποιηθούν οι διαδικάσιες και να εξαλειφθεί ο εξωτερικός διαμεσολαβητής. Συνεπώς, η ασφάλεια τους λαμβάνει όλο και μεγαλύτερη αξία και προσοχή. Θα αναλύσουμε γνωστές ευπάθειες των smart contracts και τρόπους αποφυγής τους με έμφαση στα εργαλεία στατικής ανάλυσης.

Huilin Zhang, Wenrui Zhu, Cai Wang, Ye Wang · 5 authors

Abstract As an important supplementary method to help market entities to complete consumption responsibility weights of renewable energy in China, excessive consumption transaction needs an efficient and security trading mechanism. Therefore, a decentered listing trading system based on blockchain smart contract is proposed, which utilizes P2P transaction mode to complete the listing and delisting process of excessive consumption transaction. The feasibility of this trading system is verified by an example designed on Ethereum platform with compiling and allocating of smart contract, synchronization of ethernet and smart contract, and announcement of transaction information.

Nazan Şak

Kripto paralar, teknolojideki ilerlemeler ile birlikte ilk ortaya çıktığı günden itibaren hızlı bir şekilde gelişme göstererek işlem görmeye başlamıştır. Matematiksel algoritmalar kullanılarak özel şifreleme mekanizmalarıyla blok zincir (blockchain) olarak adlandırılan sistemler ile üretilen kripto paralar içinde Bitcoin, en yüksek piyasa değerine ve işlem hacmine sahip sanal paradır. Zamanla Bitcoin’e alternatif birçok sanal para da bu sistem içinde yer almaya başlamıştır. Bu çalışmada, son dönemde diğer yatırım araçlarına alternatif olarak görülen kripto paralardan piyasa değeri olarak ilk 30 içinde yer alan ve ilgili dönemde verisine ulaşılabilen 13 kripto para kullanılmıştır. Pozitif ve negatif şokların yaşandığı kazandıran ve kaybettiren dönemlerde bu paralar arasındaki ilişki, Hatemi-J asimetrik nedensellik testiyle incelenmiştir. Bu amaçla, Bitcoin, Ethereum, Ripple, Bitcoin cash, Litecoin, Eos, Binance coin, Stellar, Monero, Dash, Ethereum classic, Neo ve Zcash kripto paralarının 26.7.2017-27.2.2020 tarihleri arasındaki günlük kapanış fiyatları verileri kullanılmıştır. Yapılan analiz sonucunda özellikle kazandıran dönemlerde kişilerin yatırım araçlarını çeşitlendirebildiği; kaybettiren dönemlerde ise daha az riskli olarak görülen kripto paralara yatırım yaptığı gözlenmiştir. Negatif şok dönemlerinde en çok tercih edilen kripto para Ripple, Binance coin, Bitcoin cash ve Monero iken; pozitif şok dönemlerinde Bitcoin, Ripple, Binance coin, Dash ve Bitcoin cash’dir.

Hao Wang, Chunpeng Ge, Zhe Liu

Blockchain technology enables global mutually trustless participants to reach a consensus on the final state of permissionless distributed and decentralized ledgers. Due to its properties of openness, transparency, irreversibility, and credibility, many systems have been built based on blockchains' structure, such as Bitcoin and Ethereum. With the wide application of blockchains, however, many security problems still exist in blockchains and there have been many malicious attacks against blockchain systems. Although these attacks have been proposed, there lacks a systematic exploration of how these attacks have been conducted and what underlying relationship they have. In this paper, we firstly present and summarize several current attacks on blockchains in three aspects: system deficiency attacks, mining attacks, and network-level attacks. Secondly, we conduct a systematic analysis and evaluation of the possibility of these attacks occurring on major blockchain platforms. Finally, we motivate some research perspectives and challenges for blockchain system security and highlight some potential solutions to these problems.

Ohm Patel

Cryptocurrencies have enhanced financial transactions, but being decentralized, they pose numerous security threats to their users, warranting new anomaly detection systems for fraud prevention.The present research focuses on the machine learning (ML) techniques used in detecting suspicious activities in cryptocurrency networks, focusing on their contribution to AML and CFT compliance.The paper also compares supervised and unsupervised learning techniques and their merits and demerits.The supervised learning techniques, including Decision Trees, SVMs, and Neural Networks, are presented for their accuracy and flexibility, and, on the other hand, the unsupervised learning approaches, including Clustering, Isolation Forests, and Autoencoders are considered for their potential to discover new fraud patterns even if the training data is not labeled.An analysis of the use of explainability tools such as LIME and SHAP in artificial intelligence systems is also carried out to improve how users understand the results given to them by the AI models.These models have their real-life application illustrated by case studies, which prove helpful in identifying anomalies in Bitcoin and Ethereum transactions.New research directions suggest improvements in machine learning methods, the connection of the results with analysis tools based on blockchain, and cooperation with relevant authorities to improve the identification of threats and conformity with established guidelines.The potential of applying the idea of this work in traditional finance and cybersecurity is discussed, highlighting the possibility of applying ML in multiple fields to enhance security and compliance.The study then informs the significance of continued research and collaboration among disciplines to combat the emerging issues of financial fraud and cybercrimes related to cryptocurrencies.

Berat ÇAĞLAR, Uğur Yavuz

Bilgisayar ve internet teknolojilerindeki gelişmeler, hayatımızın her alanında etkisini gösterdiği gibi ekonomi boyutunda da etkileri yadsınamaz. Ekonomi alanındaki yeni ekonomik reform mahiyetinde kabul gören bu yenilikler FinTek (Finans ve Teknoloji) kapsamı içerisinde yer almaktadır. FinTech inovasyonu ile ekonomide ademi merkeziyetçi bir akım başlatan Bitcoin, şu an dünya ekonomisinde önemli bir yere sahiptir. Bitcoin ile hayatımıza giren Blockchain (Blokzincir) teknolojisinin ise yakın gelecekte hayatımızın vazgeçilmez bir parçası haline geleceği öngörülmektedir. Tüm bu gelişmeler ışığında günümüzün popüler teknolojilerinden olan yapay zeka yöntemlerinden yararlanılarak, kitle haberleşme aracı olarak tanımlanan gazetelerde yer alan, insan ve toplumu ilgilendiren ve toplumun en önemli ihtiyaçlarından olan haberlerin, geleceğin para birimi olarak görülen Bitcoin üzerindeki etkileri ortaya konmak istenmiştir. Bu bağlamda 5 ulusal finans gazetesi belirlenip, Bitcoin’in ilk halka arz yılından itibaren yayınlanan haberleri olumlu ve olumsuz yorum içeriklerine göre sayısallaştırarak, Bitcoin altyapı teknolojisi olan blokzinciri verileri ile ikinci en popüler kripto para olan Ethereum’un ABD dolar karşılığı alınarak, yapay sinir ağları teknikleri ile oluşturulan ağ içerisinde ilişkilendirilmiştir. Çalışma sonucunda %99’luk tahminsel başarı içeren yapay sinir ağında, finansal gazetelerin yayınlamış olduğu Bitcoin içerikli haberlerin, Bitcoin fiyat tahminine güçlü bir etkisinin olmadığı sonucuna varılmıştır. Bunulan birlikte seçilen finansal gazetelerden The Wall Street gazetesinin diğer finansal gazetelere oranla Bitcoin fiyat tahminde nispeten etkisinin olduğu saptanmıştır.

Kiattikul Sooksomsatarn Et al.

Nowadays, Blockchain is a disruptive technology, particularly in the financial context. Moreover, Blockchain is behind the success of cryptocurrencies, e.g., Bitcoin and Ethereum. Unlike traditional currencies, cryptocurrencies are entirely virtual. There is no physical money, but it can directly make payments in digital currency from one person to another without intermediaries. Moreover, Hashing's cryptographic algorithm makes Blockchain resist tampering from any transacting participants because the submitted block cannot be altered or re-engineered. However, another big problem is how users of cryptocurrencies stop somebody from adding or editing a transaction that spends someone else's money to them. To do this, Blockchain needs another cryptosystem called Public/Private Keys, a primitive asymmetric cryptosystem, e.g., the RSA encryption, to sign the transactions for proving the authenticity of the ownership without revealing the signed secret information. The generated public key is regarded as a ledger account number or digital wallet of the sender and the recipient. Simultaneously, the paired private keys are used to identify whether the digital wallets' owners are authentic. As growing network entities and propagated Blockchain transactions, computing millions of replicated tokens in the blocks to sign and verify the digital wallet's ownership is computationally expensive. However, a certain of chosen arithmetical transformations that can simplify mathematical cost can significantly reduce computational complexity. This research's main contribution is developing a protocol that can reduce the complexity and mathematical cost in generating the digital wallet and verifying its authenticity of ownership. Finally, performance analyses of the RSA algorithm for the protocol have been measured and visualized using Python.

Iago Sestrem Ochôa, Valderi Reis Quietinho Leithardt, Leonardo Calbusch, Juan F. De Paz · 7 authors

Since the early 2000s, life in cities has changed significantly due to the Internet of Things (IoT). This concept enables developers to integrate different devices collecting, storing, and processing a large amount of data, enabling new services to improve various professional and personal activities. However, privacy issues arise with a large amount of data generated, and solutions based on blockchain technology and smart contract have been developed to address these issues. Nevertheless, several issues must still be taken into account when developing blockchain architectures aimed at the IoT scenario because security flaws still exist in smart contracts, mainly due to the lack of ease when building the code. This article presents a blockchain storage architecture focused on license plate recognition (LPR) systems for smart cities focusing on privacy, performance, and security. The proposed architecture relies on the Ethereum platform. Each smart contract matches the privacy preferences of a license plate to be anonymized through public encryption. The storage of data captured by the LPR system can only be done if the smart contract enables it. However, in the case of motivation foreseen by the legislation, a competent user can change the smart contract and enable the storage of the data captured by the LPR system. Experimental results show that the performance of the proposed architecture is satisfactory, regarding the scalability of the built private network. Furthermore, tests on our smart contract using security and structure analysis tools on the developed script demonstrate that our solution is fraud-proof. The results obtained in all experiments bring evidence that our architecture is feasible to be used in real scenarios.

Sara Ghaemi, Sara Rouhani, Rafael Belchior, Rui Santos Cruz · 6 authors

The maturing of blockchain technology leads to heterogeneity, where multiple solutions specialize in a particular use case. While the development of different blockchain networks shows great potential for blockchains, the isolated networks have led to data and asset silos, limiting the applications of this technology. Blockchain interoperability solutions are essential to enable distributed ledgers to reach their full potential. Such solutions allow blockchains to support asset and data transfer, resulting in the development of innovative applications. This paper proposes a novel blockchain interoperability solution for permissioned blockchains based on the publish/subscribe architecture. We implemented a prototype of this platform to show the feasibility of our design. We evaluate our solution by implementing examples of the different publisher and subscriber networks, such as Hyperledger Besu, which is an Ethereum client, and two different versions of Hyperledger Fabric. We present a performance analysis of the whole network that indicates its limits and bottlenecks. Finally, we discuss the extensibility and scalability of the platform in different scenarios. Our evaluation shows that our system can handle a throughput in the order of the hundreds of transactions per second.

Rachit Agarwal, Tanmay Thapliyal, Sandeep K. Shukla

Different types of malicious activities have been flagged in multiple\npermissionless blockchains such as bitcoin, Ethereum etc. While some malicious\nactivities exploit vulnerabilities in the infrastructure of the blockchain,\nsome target its users through social engineering techniques. To address these\nproblems, we aim at automatically flagging blockchain accounts that originate\nsuch malicious exploitation of accounts of other participants. To that end, we\nidentify a robust supervised machine learning (ML) algorithm that is resistant\nto any bias induced by an over representation of certain malicious activity in\nthe available dataset, as well as is robust against adversarial attacks. We\nfind that most of the malicious activities reported thus far, for example, in\nEthereum blockchain ecosystem, behaves statistically similar. Further, the\npreviously used ML algorithms for identifying malicious accounts show bias\ntowards a particular malicious activity which is over-represented. In the\nsequel, we identify that Neural Networks (NN) holds up the best in the face of\nsuch bias inducing dataset at the same time being robust against certain\nadversarial attacks.\n

Monika, Ankit Goyal, Shivam Raina, Kashish Bhatia · 5 authors

Blockchain technology is reaching mainstream users due to its adoption by a large number of enterprises. Numerous new blockchain platforms and projects are emerging every year, intending to become the best blockchain. However, blockchain technology is far from reaching its full potential because of siloed blockchain platforms. Hence different blockchains should be able to interact with each other for carrying out data sharing and asset transfer among them. In this paper, we propose an approach for atomic cross-chain transfer among heterogeneous blockchains. We provide the implementation details and working of the proposed approach for different Ethereum blockchains.

Apoorv Jain, Arun Kumar Tripathi, N. Chandra, P. Chinnasamy

In today's world, data is one of the most important assets than any other. Every user wants to secure their data from the outer world. Blockchain is the prominent technology that can provide the security and loyalty of data. Initially, blockchain has been used for the cryptocurrency and all the data were available on the public distributed ledger. But now a days, private blockchain is widely used within the organizations for data security. Blockchain engenders decentralized systems in which data can be send and receive securely and efficiently over the network. It means there is everything is hidden from the outer world; only authorized users have the authority to read and write the data on the network. World's topmost industries; like Walmart, IBM, Google, etc. are adopting the blockchain technology to build the Decentralized Applications (DApps). Decentralized Applications are the smart systems that are executed on a distributed computer network. Blockchain enables one of the most secure applications called Smart Contract. Smart Contracts are the computerized and secured distributed ledgers that enable secure, transparent, and tamper-proof transactions. Smart contracts create and verify the data with the help of hashing. It is a mathematical procedure that uses the most powerful algorithm cryptographic Hash Algorithm i.e. SHA-256. It engenders 256-bit signature for the input text. Ethereum Blockchain Platform is a widely used platform to build the DApps. This platform is a public network platform, which is open to all and anyone can participate in this network to send and receives the transactions. Blockchain Technology is enabled in every sector like marketing, business, education and supply-chain, etc. This paper carries out the study Ethereum Blockchain Platform in Education System. We have developed an application for the Online-Examination System using Blockchain Ethereum Platform with features of Smart Contracts that enables server runtime environment NodeJS and MongoDB database system. Blockchain-based system is truly more secure than all the Cloud-based systems. We have also analysed that how blockchain based online examination is more trustworthy as compare the other systems.

Tomáš Krupa, Michal Ries, Ivan Kotuliak, Kristián Košťál · 5 authors

Smart contracts belong to the most rapidly growing aspect of the world of cryptocurrencies. This phenomenon attracts great attention from researchers but also the business community, and the development brings daily a lot of novel applications. Smart contracts allow running contract code transparently for all parties, without the need for a centralized authority. One of the smart contract applications is the issuance of digital assets, so-called tokens, serving as fundraising fuel for Initial Coin Offerings. ICOs bring a new easy, and bureaucracyless way for startups to raise considerable funds from crowds with incredible speed. However, the technology hides a dark side in the form of speculative scams, hardly distinguishable from genuine fundraising activities. Evaluation audit of ICOs associated with the underlying security of smart contracts is a complex issue requiring many efforts. This paper focuses on one of the most popular blockchain frameworks, Ethereum, a prominent ICO and smart contract platform, and its dominant programming language, Solidity.

Sarjana Singh, Sumit Kumar

Blockchain was mainly introduced for secure transactions in connection with the mining of cryptocurrency Bitcoin. This article discusses the fundamental concepts of blockchain technology and its components, such as block header, transaction, smart contracts, etc. Blockchain uses the distributed databases, so this article also explains the advantages of distributed Blockchain over a centrally located database. Depending on the application, Blockchain is broadly categorized into two categories; Permissionless and Permissioned. This article elaborates on these two categories as well. Further, it covers the consensus mechanism and its working along with an overview of the Ethereum platform. Blockchain technology has been proved to be one of the remarkable techniques to provide security to IoT devices. An illustration of how Blockchain will be useful for IoT devices has been given. A few applications are also illustrated to explain the working of Blockchain with IoT.

Yunguo Guan, Hui Zheng, Jun Shao, Rongxing Lu · 5 authors

Due to the big data blowout from the Internet of Things and the rapid development of cloud computing, outsourcing computation has received considerable attention in recent years. Particularly, many outsourcing computation schemes have been proposed to dedicate the outsourcing polynomial computation due to its use in numerous fields, such as data analysis and machine learning. However, none of those schemes are practical enough, as they either require some time-consuming cryptographic operations to achieve fairness between the user and the worker, or cannot allow the user to outsource arbitrary polynomial to the worker, or need two non-collusive workers. To tackle these challenges, in this article, we propose a new outsourcing polynomial computation scheme by employing a variant of Horner’s method and the blockchain technology. Specifically, the former makes the computational cost on the worker side as low as possible, and the latter guarantees the fairness between the user and the worker if the result from the worker can be publicly verified. To achieve the public verifiability property, we apply the sampling technique, which is effective in our proposal according to a game-theoretic analysis. Furthermore, we also implement a prototype of our proposal and run it on an Ethereum test net. The extensive experimental results demonstrate that our proposal is efficient in terms of computational cost.