Esam Mahdi, Víctor Leiva, Saed Mara’Beh, Carlos Martín-Barreiro
In a real-world situation produced under COVID-19 scenarios, predicting cryptocurrency returns accurately can be challenging. Such a prediction may be helpful to the daily economic and financial market. Unlike forecasting the cryptocurrency returns, we propose a new approach to predict whether the return classification would be in the first, second, third quartile, or any quantile of the gold price the next day. In this paper, we employ the support vector machine (SVM) algorithm for exploring the predictability of financial returns for the six major digital currencies selected from the list of top ten cryptocurrencies based on data collected through sensors. These currencies are Binance Coin, Bitcoin, Cardano, Dogecoin, Ethereum, and Ripple. Our study considers the pre-COVID-19 and ongoing COVID-19 periods. An algorithm that allows updated data analysis, based on the use of a sensor in the database, is also proposed. The results show strong evidence that the SVM is a robust technique for devising profitable trading strategies and can provide accurate results before and during the current pandemic. Our findings may be helpful for different stakeholders in understanding the cryptocurrency dynamics and in making better investment decisions, especially under adverse conditions and during times of uncertain environments such as in the COVID-19 pandemic.
Ethereum smart contracts have been gaining popularity toward the automation of so many domains, i.e., FinTech, IoT, and supply chain, which are based on blockchain technology. The most critical domain, e.g., FinTech, has been targeted by so many successful attacks due to its financial worth of billions of dollars. In all attacks, the vulnerability in the source code of smart contracts is being exploited and causes the steal of millions of dollars. To find the vulnerability in the source code of smart contracts written in Solidity language, a state-of-the-art work provides a lot of solutions based on dynamic or static analysis. However, these tools have shown a lot of false positives/negatives against the smart contracts having complex logic. Furthermore, the output of these tools is not reported in a standard way with their actual vulnerability names as per standards defined by the Ethereum community. To solve these problems, we have introduced a static analysis tool, SESCon (secure Ethereum smart contract), applying the taint analysis techniques with XPath queries. Our tool outperforms other analyzers and detected up to 90% of the known vulnerability patterns. SESCon also reports the detected vulnerabilities with their titles, descriptions, and remediations as per defined standards by the Ethereum community. SESCon will serve as a foundation for the standardization of vulnerability detection.
Tema ovog rada je primjena blockchain tehnologije u suvremenom elektroenergetskom sustavu. Blockchain tehnologija je zasnovana na peer to peer principu. Svaki čvor u sustavu dobiva svoju kopiju "lanca" koju čuva. Promjena u lancu tj. dodavanje nove transakcije iziskuje zajednički rad sudionika sustava. Jedan čvor izdaje transakciju koja se potvrđuje od drugih korisnika. Postoji puno vrsta različitih konsenzusa. Najčešće korišteni konsenzusi su Proof of Work i Proof of Stake. Takozvani rudari rješavaju kompleksne algoritme da bi potvrdili transakciju. To je izrazito kompleksan proces koji osigurava stalnu funkciju mreže. Blockchain izbacuje treću stranu u razmjeni informacija te je zamjenjuje sa transparentom i sigurnom mrežom. Na taj način sve strane profitiraju i dobivaju pouzdan sustav za korištenje. Prva cjelina koja se obrađuje u radu su solarne elektrane. Objašnjava se detaljnije tehnologija i njena primjena. Navode se potrebni dijelovi za izgradnju solarnog sustava na krovu kuće. Svaki dio se detaljnije objašnjava. Objašnjava se princip rada cijelog sustava te se navode tri osnovna sustava: sustav povezan na mrežu, samostalni sustav i hibridni sustav. Svaki od ta tri sustava se objašnjava detaljnije. Druga cjelina su baterijski spremnici. Kroz cjelinu se obrađuju osnovni pojmovi i karakteristične veličine vezane za baterijske spremnike. Navode se tri vrste baterijski spremnika: olovne, li-ionske i baterije na slanu vodu. Svaki od tih spremnika je detaljnije opisan da bi se što bolje razumio. Navode se baterijski spremnici sa današnjeg tržišta te primjećujemo trend ulaska velikih tvrtka u to područje. Za kraj poglavlja daje se osvrt na isplativost baterijskih spremnika u kućanstvima. Treća cjelina su mikromreže. U ovom poglavlju čitatelj može saznati nešto više o mikromreža. Objašnjava se što su mikromreže te njihov osnovni koncept. Navode se tri osnove vrste mikromreža: urbane, udaljene i agilne. Svaka od tih vrsta se pobliže objašnjava. Nakon toga se objašnjava detaljnije arhitektura mikromreža te potom se navode mogućnosti upravljanja. Upravljanje se dijeli u tri skupine: primarno, sekundarno i tercijarno. Ta se upravljanje izvode prema hijerarhiji. Za kraj poglavlja navode se neke prednosti i nedostaci koncepta mikromreža. Četvrta cjelina je opis Blockchain tehnologije. Kroz ovo poglavlje objašnjava se princip rada tehnologije. Navodi se nekoliko vrsta konsenzusa te se oni detaljnije objašnjavaju. Kao najpoznatije kriptovalute ukratko se objašnjavaju Bitcoin i Ethereum. Poglavlje dosta detaljno objašnjava tehnologiju te prikazuje njenu arhitekturu i navodi kriterij za tehnološku podobnost. Peta cjelina je usmjerena isključivo na primjenu blockchain tehnologije u elektroenergetskom sustavu. Objašnjava se ogromni potencijal tehnologije da unaprijedi poslovanje energetskih tvrtki. Analizira se veleprodaja električne energije i daje se moguće unapređenje strukture tržišta. Za kraj poglavlja se govori o digitalizaciji i IoT platformama. Digitalizacije će u budućnosti zahvatiti svaki sektor tako da je izrazio bitno objasnit način na koji će se implementira u elektroenergetski sustav. Šesta cjelina govori o Blockchain aplikacijama u mikromrežama. Generalna ideja svega je napraviti funkcionalnu platformu pomoću koje korisnici mogu trgovati sa svojim energetskim viškom. U slučaju manjka energije mogu je kupiti od susjeda ili bilo kojeg drugog korisnika platforme. Neki projekti koji se izdvajaju su: Brooklyn MicroGrid od LO3 Energy-a, Power Ledger i SunContract. Ove tri platforme se detaljnije objašnjavaju te se još navodi Key2Energery kao rani projekt sa velikim potencijalom. Sedma i zadnja cjelina upoznaje čitatelje s nekim problemima blockchain tehnologije. Iako tehnologija ima puno pozitivnih strana postoje i negativne sa gledišta potrošnje energije i emisije CO2. Kroz ovo poglavlje daju se estimacije potrošnje energije i emisije CO2 Proof of Work blockchaina. Ujedno se navodi utjecaj tehnologije na društvo i sveukupno globalno gospodarstvo te se uz to sve prilažu kratki proračuni.
Ethereum is one of the most popular blockchain systems that support more than half a million transactions every day and foster miscellaneous decentralized applications with its Turing-complete smart contract machine. Whereas it remains mysterious what the transaction pattern of Ethereum is and how it evolves over time. In this article, we study the evolutionary behavior of Ethereum transactions from a temporal graph point of view. We first develop a data analytic platform to collect external transactions associated with users as well as internal transactions initiated by smart contracts. Three types of temporal graphs, user-to-user, contract-to-contract, and user-contract graphs, are constructed according to trading relationships and are segmented with an appropriate time window. We observe a strong correlation between the size of the user-to-user transaction graph and the average Ether price in a time window, while no evidence of such linkage is shown at the average degree, average edge weights, and average triplet closure duration. The macroscopic and microscopic burstiness of Ethereum transactions are validated. We analyze the Gini indexes of the transaction graphs and the user wealth in which Ethereum is found to be very unfair since the very beginning, in a sense, “the rich is already very rich.”
Mahdi Ghaemi Asl, Muhammad Mahdi Rashidi, Seyed Ali Hosseini Ebrahim Abad
Purpose The purpose of this study is to investigate the correlation between the price return of leading cryptocurrencies, including Bitcoin, Ethereum, Ripple, Litecoin, Monero, Stellar, Peercoin and Dash, and stock return of technology companies' indices that mainly operate on the blockchain platform and provide financial services, including alternative finance, democratized banking, future payments and digital communities. Design/methodology/approach This study employs a Bayesian asymmetric dynamic conditional correlation multivariate Generalized Autoregressive Conditional Heteroskedasticity (GARCH) (BADCC-MGARCH) model with skewness and heavy tails on daily sample ranging from August 11, 2015, to February 10, 2020, to investigate the dynamic correlation between price return of several cryptocurrencies and stock return of the technology companies' indices that mainly operate on the blockchain platform. Data are collected from multiple sources. For parameter estimation and model comparison, the Markov chain Monte Carlo (MCMC) algorithm is employed. Besides, based on the expected Akaike information criterion (EAIC), Bayesian information criterion (BIC), deviance information criterion (DIC) and weighted Deviance Information Criterion (wDIC), the skewed-multivariate Generalized Error Distribution (mvGED) is selected as an optimal distribution for errors. Finally, some other tests are carried out to check the robustness of the results. Findings The study results indicate that blockchain-based technology companies' indices' return and price return of cryptocurrencies are positively correlated for most of the sampling period. Besides, the return price of newly invented and more advanced cryptocurrencies with unique characteristics, including Monero, Ripple, Dash, Stellar and Peercoin, positively correlates with the return of stock indices of blockchain-based technology companies for more than 93% of sampling days. The results are also robust to various sensitivity analyses. Research limitations/implications The positive correlation between the price return of cryptocurrencies and the return of stock indices of blockchain-based technology companies can be due to the investors' sentiments toward blockchain technology as both cryptocurrencies and these companies are based on blockchain technology. It could also be due to the applicability of cryptocurrencies for these companies, as the price return of more advanced and capable cryptocurrencies with unique features has a positive correlation with the return of stock indices of blockchain-based technology companies for more days compared to the other cryptocurrencies, like Bitcoin, Litecoin and Ethereum, that may be regarded more as speculative assets. Practical implications The study results may show the positive role of cryptocurrencies in improving and developing technology companies that mainly operate on the blockchain platform and provide financial services and vice versa, suggesting that managers and regulators should pay more attention to the usefulness of cryptocurrencies and blockchains. This study also has important risk management and diversification implications for investors and companies investing in cryptocurrencies and these companies' stock. Besides, blockchain-based technology companies can add cryptocurrencies to their portfolio as hedgers or diversifiers based on their strategy. Originality/value This is the first study analyzing the connection between leading cryptocurrencies and technology companies that mainly operate on the blockchain platform and provide financial services by employing the Bayesian ssymmetric DCC-MGARCH model. The results also have important implications for investors, companies, regulators and researchers for future studies.
Anderson Melo de Morais, Jorge da Silva Correia Neto, Robson Wagner Albuquerque de Medeiros, Obionor de Oliveira Nóbrega · 5 authors
Education generates a considerable amount of data and information, it is necessary to manage this data securely, avoiding problems of falsification and tampering with diplomas, certificates, and other important student documents. In addition, distance learning is becoming more popular due to the Covid-19 pandemic period, where courses are offered in virtual learning environments such as Moodle. Blockchain technology can be used as a tool to ensure the security of data managed by Moodle. However, there is a gap in current state-of-the-art solutions for integrating these data with Blockchain platforms. This work proposes BlockMoodle, a solution developed to integrate Moodle with Blockchain Ethereum. This work also performs an analysis of the financial cost of using the tool. In addition, a performance evaluation of the proposed solution is also carried out considering different usage scenarios. Finally, the conclusions and future work to be developed are presented.
Sentiments are extracted from tweets with the hashtag of cryptocurrencies to predict the price and sentiment prediction model generates the parameters for optimization procedure to make decision and re-allocate the portfolio in the further step. Moreover, after the process of prediction, the evaluation, which is conducted with RMSE, MAE and R2, select the KNN and CART model for the prediction of Bitcoin and Ethereum respectively. During the process of portfolio optimization, this project is trying to use predictive prescription to robust the uncertainty and meanwhile take full advantages of auxiliary data such as sentiments. For the outcome of optimization, the portfolio allocation and returns fluctuate acutely as the illustration of figure.
Ethereum is a public blockchain platform with smart contract. However, it has transaction privacy issues due to the openness of the underlying ledger. Decentralized mixing schemes are presented to hide transaction relationship and transferred amount, but suffer from high transaction cost and long transaction latency. To overcome the two challenges, we propose the idea of batch accounting, adopting batch processing at the time of accounting. For further realization, we introduce payment channel technology into decentralized mixer. Since intermediate transactions between two parties do not need network consensus, our scheme can reduce both transaction cost and transaction latency. Moreover, we provide informal definitions and proofs of our scheme's security. Finally, our scheme is implemented based on zk-SNARKs and Ganache, and experimental results show that the higher number of transactions in batch, the better our scheme performs.
Open access
Blockchain Technology Applications and Security
Internet Traffic Analysis and Secure E-voting
Advanced Steganography and Watermarking Techniques
In this paper we describe LUNES-Blockchain, an agent-based simulator of blockchains that relies on Parallel and Distributed Simulation (PADS) techniques to obtain high scalability. The software is organized as a multi-level simulator that permits to simulate a virtual environment, made of many nodes running the protocol of a specific Distributed Ledger Technology (DLT), such as the Bitcoin or the Ethereum blockchains. This virtual environment is executed on top of a lower-level Peer-to-Peer (P2P) network overlay, which can be structured based on different topologies and with a given number of nodes and edges. Functionalities at different levels of abstraction are managed separately, by different software modules and with different time granularity. This allows for accurate simulations, where (and when) it is needed, and enhances the simulation performance. Using LUNES-Blockchain, it is possible to simulate different types of attacks on the DLT. In this paper, we specifically focus on the P2P layer, considering the selfish mining, the 51% attack and the Sybil attack. For which concerns selfish mining and the 51% attack, our aim is to understand how much the hash-rate (i.e. a general measure of the processing power in the blockchain network) of the attacker can influence the outcome of the misbehaviour. On the other hand, in the filtering denial of service (i.e. Sybil Attack), we investigate which dissemination protocol in the underlying P2P network makes the system more resilient to a varying number of nodes that drop the messages. The results confirm the viability of the simulation-based techniques for the investigation of security aspects of DLTs.
In this paper we describe LUNES-Blockchain, an agent-based simulator of\nblockchains that relies on Parallel and Distributed Simulation (PADS)\ntechniques to obtain high scalability. The software is organized as a\nmulti-level simulator that permits to simulate a virtual environment, made of\nmany nodes running the protocol of a specific Distributed Ledger Technology\n(DLT), such as the Bitcoin or the Ethereum blockchains. This virtual\nenvironment is executed on top of a lower-level Peer-to-Peer (P2P) network\noverlay, which can be structured based on different topologies and with a given\nnumber of nodes and edges. Functionalities at different levels of abstraction\nare managed separately, by different software modules and with different time\ngranularity. This allows for accurate simulations, where (and when) it is\nneeded, and enhances the simulation performance. Using LUNES-Blockchain, it is\npossible to simulate different types of attacks on the DLT. In this paper, we\nspecifically focus on the P2P layer, considering the selfish mining, the 51%\nattack and the Sybil attack. For which concerns selfish mining and the 51%\nattack, our aim is to understand how much the hash-rate (i.e. a general measure\nof the processing power in the blockchain network) of the attacker can\ninfluence the outcome of the misbehaviour. On the other hand, in the filtering\ndenial of service (i.e. Sybil Attack), we investigate which dissemination\nprotocol in the underlying P2P network makes the system more resilient to a\nvarying number of nodes that drop the messages. The results confirm the\nviability of the simulation-based techniques for the investigation of security\naspects of DLTs.\n
Vishal Sharma, Zengpeng Li, Paweł Szałachowski, Teik Guan Tan · 5 authors
Decentralized control, low-complexity, flexible and efficient communications are the requirements of an architecture that aims to scale blockchains beyond the current state. Such properties are attainable by reducing ledger size and providing parallel operations in the blockchain. Sharding is one of the approaches that lower the burden of the nodes and enhance performance. However, the current solutions lack the features for resolving concurrency during cross-shard communications. With multiple participants belonging to different shards, handling concurrent operations is essential for optimal sharding. This issue becomes prominent due to the lack of architectural support and requires additional consensus for cross-shard communications. Relying on the advantages of hybrid Proof-of-Work/Proof-of-Stake (PoW/PoS), like Ethereum , hybrid consensus and 2-hop blockchain , we propose Reinshard , a new blockchain that inherits the properties of hybrid consensus for optimal sharding. Reinshard uses PoW and PoS chain-pairs with PoS sub-chains for all the valid chain-pairs where the hybrid consensus is attained through Verifiable Delay Function (VDF). Our architecture provides a secure method of arranging nodes in shards and resolves concurrency conflicts using the delay factor of VDF. The applicability of Reinshard is demonstrated through security and experimental evaluations. A practical concurrency problem is considered to show the efficacy of Reinshard in providing optimal sharding.
Bertrand Meyer, Alisa Arkadova, Alexander Kogtenkov
Class invariants -- consistency constraints preserved by every operation on objects of a given type -- are fundamental to building, understanding and verifying object-oriented programs. For verification, however, they raise difficulties, which have not yet received a generally accepted solution. The present work introduces a proof rule meant to address these issues and allow verification tools to benefit from invariants. It clarifies the notion of invariant and identifies the three associated problems: callbacks, furtive access and reference leak. As an example, the 2016 Ethereum DAO bug, in which $50 million were stolen, resulted from a callback invalidating an invariant. The discussion starts with a simplified model of computation and an associated proof rule, demonstrating its soundness. It then removes one by one the three simplifying assumptions, each removal raising one of the three issues, and leading to a corresponding adaptation to the proof rule. The final version of the rule can tackle tricky examples, including "challenge problems" listed in the literature.
Cryptocurrency adalah sebuah teknologi berbasis blockchain yang sering digunakan pada saat ini sebagai mata uang digital. Bentuk cryptocurrency di minati oleh masyarakat karena pengelolaannya yang terdesentraliasi, prosesnya yang mudah, serta memungkinkan transaksi tanpa perlu adanya perantara pihak ketiga. Teknologi internet of things (IoT) telah memberikan pengaruh besar terhadap perkembangan informasi yang didapatkan untuk memantau secara langsung perubahan informasi tanpa memerlukan adanya interaksi dari manusia ke manusia ataupun dari manusia ke perangkat komputer, seperti menampilkan stabilitas cryptocurrency terutama pada Bitcoin, Ethereum, dan Binance. Penelitian ini bertujuan untuk memonitoring data secara real time dengan menggunakan aplikasi Thingspeak.com, Arduino IDE sebagai pemroses data, dan jalur pengiriman data secara real time memanfaatkan, modul ESP8266. Hasil implementasi olahan data ditampilkan pada layar oled.
The complicated environment of IoT represents a rich surface for attackers to exploit its vulnerabilities and disclose its assets. The ownership of IoT devices considers as one of the main assets that ordinarily managed by the centralized entity. The centralized entity can become a potential site of attack or become an attacker itself. The proposed approach aims to address the central authority issue by utilizing the advantage of the blockchain and Ethereum smart contract. Our approach involves playing the role of controlling the ownership functions during the device lifecycle, such as transferring the ownership, as well as, getting a trusted log of device owners from the current owner back to the origin. Our analysis shows that our solution is viable and offers a significant degree of transparency, anonymity, immutable, and non-repudiation.
Philipp Winter, Anna Harbluk Lorimer, Peter Snyder, Benjamin Livshits
Much of the recent excitement around decentralized finance (DeFi) comes from hopes that DeFi can be a secure, private, less centralized alternative to traditional finance systems but the accuracy of these hopes has to date been understudied; people moving to DeFi sites to improve their privacy and security may actually end up with less of both.
In this work, we improve the state of DeFi by conducting the first measurement of the privacy and security properties of popular DeFi applications. We find that DeFi applications suffer from the same kinds of privacy and security risks that frequent other parts of the Web. For example, we find that one common tracker has the ability to record Ethereum addresses on over 56% of websites analyzed. Further, we find that many trackers on DeFi sites can trivially link a user's Ethereum address with PII (e.g., name or demographic information) or phish users.
This work also proposes remedies to the vulnerabilities we identify, in the form of improvements to the most common cryptocurrency wallet. Our wallet modification replaces the user's real Ethereum address with site-specific addresses, making it harder for DeFi sites and third parties to (i) learn the user's real address and (ii) track them across sites.
Ethereum platforma za izgradnju pametnih ugovora temelji se na blockchain tehnologiji koja je opisana u radu "Konsenzus u Ethereum 2.0 blockchainu". PoW konsenzus mehanizam koji se koristi kod platforme Ethereum sprema svako prethodno stanje mreže na temelju kojeg se računa novo stanje što rezultira ograničenjem skalabilnosti. Zbog tog razloga u tijeku je prijelaz na novi konsenzus mehanizam kao i promjena arhitekture mreže čime će se postići povećanje skalabilnosti. U ovom radu analizira se PoS konsenzus mehanizam kao i promjena arhitekture mreže pomoću layer 2 rješenja.
Philipp Winter, Anna Harbluk Lorimer, Peter J. Snyder, Benjamin Livshits
Much of the recent excitement around decentralized finance (DeFi) comes from hopes that DeFi can be a secure, private, less centralized alternative to traditional finance systems. However, people moving to DeFi sites in hopes of improving their security and privacy may end up with less of both as recent attacks have demonstrated. In this work, we improve the understanding of DeFi by conducting the first Web measurements of the security, privacy, and decentralization properties of popular DeFi front ends. We find that DeFi applications -- or dapps -- suffer from the same security and privacy risks that frequent other parts of the Web but those risks are greatly exacerbated considering the money that is involved in DeFi. Our results show that a common tracker can observe user behavior on over 56% of websites we analyzed and many trackers on DeFi sites can trivially link a user's Ethereum address with PII (e.g., user name or demographic information), or phish users by initiating fake Ethereum transactions. Lastly, we establish that despite claims to the opposite, because of companies like Amazon and Cloudflare operating significant Web infrastructure, DeFi as a whole is considerably less decentralized than previously believed.
Jon Oakley, Carl Worley, Lu Yu, Richard Brooks · 7 authors
Clinical trials are a multi-billion dollar industry. One of the biggest challenges facing the clinical trial research community is satisfying Part 11 of Title 21 of the Code of Federal Regulations and ISO 27789. These controls provide audit requirements that guarantee the reliability of the data contained in the electronic records. Context-aware smart devices and wearable IoT devices have become increasingly common in clinical trials. Electronic Data Capture (EDC) and Clinical Data Management Systems (CDMS) do not currently address the new challenges introduced using these devices. The healthcare digital threat landscape is continually evolving, and the prevalence of sensor fusion and wearable devices compounds the growing attack surface. We propose Scrybe, a permissioned blockchain, to store proof of clinical trial data provenance. We illustrate how Scrybe addresses each control and the limitations of the Ethereum-based blockchains. Finally, we provide a proof-of-concept integration with REDCap to show tamper resistance.