Sarada Prasad Gochhayat, Sachin Shetty, Ravi Mukkamala, Peter Foytik · 6 authors
Blockchain promises to provide a distributed and decentralized means of trust among untrusted users. However, in recent years, a shift from decentrality to centrality has been observed in the most accepted Blockchain system, i.e., Bitcoin. This shift has motivated researchers to identify the cause of decentrality, quantify decentrality and analyze the impact of decentrality. In this work, we take a holistic approach to identify and quantify decentrality in Blockchain based systems. First, we identify the emergence of centrality in three layers of Blockchain based systems, namely governance layer, network layer and storage layer. Then, we quantify decentrality in these layers using various metrics. At the governance layer, we measure decentrality in terms of fairness, entropy, Gini coefficient, Kullback-Leibler divergence, etc. Similarly, in the network layer, we measure decentrality by using degree centrality, betweenness centrality and closeness centrality. At the storage layer, we apply a distribution index to define centrality. Subsequently, we evaluate the decentrality in Bitcoin and Ethereum networks and discuss our observations. We noticed that, with time, both Bitcoin and Ethereum networks tend to behave like centralized systems where a few nodes govern the whole network.
Cryptocurrency has become most sought after digital payment system these days and has been regarded as the safest mode of transferring money and making payments. The functionality of the cryptocurrency highly depends upon the use of advanced technology and resulted in the emergence of a number of cryptocurrencies like Bitcoin, Ripple, Ethereum, etc. The evolution and growth of cryptocurrency have been tremendous during the last 10 years and has revolutionised the whole financial sector. The cryptocurrency provides immense opportunities to the users in the form of increased job propensities and new market ventures along with certain challenges like volatility, lack of markets and so on. The risk and return factors involved with the usability and adaptability of cryptocurrency has also impacted the users in both positive and negative ways. Hence, the current research study provides detailed insights about cryptocurrency, its growth, opportunities, and future prospects in an adequate manner.
Cryptocurrency is a recent and popular topic that attracts the interest of investors and fund managers. Beyond the market discipline, researchers question the interaction between cryptocurrencies and macroeconomic variables. This study focuses on how the changes in gold and oil prices affect the daily price movements of various cryptocurrencies. The daily database used in this study includes the prices of the cryptocurrencies such as Bitcoin, Tether, Ethereum, Litecon and EOS for the period of August 1, 2017 and April 3, 2019. Initially, the stationarity of the time series is tested by The existence of the cointegration relationship among the series is tested by The presence of causality relationships among the series is investigated with the Dolado and Ltkepohl (1996) causality test. The empirical results support that there exists a cointegration relationship only in between Tether and gold and oil prices.
Since their introduction, Online Social Networks (OSNs) have transformed the way people interact with each other. Lately, a new trend is rising in the development of OSNs, fueled by an increasing interest of the blockchain technology and the benefits it can bring to the world of OSNs. Blockchain Online Social Media (BOSMs) are Social Media applications that are supported by the blockchain technology. Thanks to a blockchain, BOSMs either try to enforce the privacy of the users or try to redistribute with their users the economic wealth generated by the platform through a rewarding system. There are countless BOSMs available which incorporate a rewarding system. Among them, Steemit can be considered the most well-known platform exceeding 1 million registered users. Steemit is supported by the blockchain Steem, which is a blockchain that natively supports the development of social applications by the usage of transactions that model social activity. Even if other important blockchains, such as Ethereum has been widely analysed, at the best of our knowledge, no study exists concerning the topology of the transactions graph of Steem. The main goal of this paper is to study the structure of the Steem transaction graph to understand its characteristics and unveil crucial knowledge concerning their users. More in detail, we build the Interactions Graph and, after its study, we evaluate three subgraphs that capture its social and monetary aspects. The degree distributions of the graphs follow a power-law. Additionally, we detect a substantial number of bots that offer paid services on the platform among the most active users. Lastly, the investigation of the four analysed graphs through a bow-tie structure, suggesting that half of the users have a passive social behaviour and that 80% of the users tend to accrue economic value
The exploitation of smart-contract vulnerabilities can have catastrophic consequences such as the loss of millions of pounds worth of crypto assets. Formal verification can be a useful tool in identifying vulnerabilities and proving that they have been fixed. In this paper, we present a formalisation of Solidity and the Ethereum blockchain using the Solid language and its blockchain; a Solid program is obtained by explicating/desugaring a Solidity program. We make some abstractions that over-approximate the way in which Solidity/Ethereum behave. Based on this formalisation, we create Solidifier: a bounded model checker for Solidity. It translates Solid into Boogie, an intermediate verification language, that is later verified using Corral, a bounded model checker for Boogie. Unlike much of the work in this area, we do not try to find specific behavioural/code patterns that might lead to vulnerabilities. Instead, we provide a tool to find errors/bad states, i.e. program states that do not conform with the intent of the developer. Such a bad state, be it a vulnerability or not, might be reached through the execution of specific known code patterns or through behaviours that have not been anticipated.
Tingting Song, Bo Cui, Ru Li, Jing Liu · 5 authors
Named Data Networking (NDN) is a new clean-slate architecture for the future Internet. Efficient content retrieval is the original intention of NDN design. The content retrieval process driven by content consumers in NDN includes the following challenges, consumers do not know whether the content exists and whether the content producer is reliable. Invalid interest packets could cause the occupation of limited network resources and DoS attack problem. To ensure the authenticity and integrity of the data packets, consumers need to pre-configure the trust schema, which is centralized and prone to the single point of failure problem. Blockchain has widespread attention to build trust in a distributed way, and Ethereum is a programmable blockchain, a decentralized smart contract platform. To lighten the burden of consumers, we proposed a Smart Contract-based Trusted Content Retrieval Mechanism (SCTCRM) for NDN in this paper. The mechanism contains a trustworthy information base for content and producers based on smart contracts, and provides content retrieval and name resolution services for content consumers. The purpose of this mechanism is to improve the efficiency and security of content retrieval process. We described the framework and the workflow of SCTCRM, and used Colored Petri Nets to create a formal mathematical model and analyze the security of the mechanism. Finally, the cost of storage and Gas in smart contracts are evaluated through the prototype deployment. From the results, we can see that the proposed mechanism is security and practicality.
Mohd Sabri Ismail, Saiful Izzuan Hussain, Mohd Salmi Md Noorani
This study explores persistent homology to detect early warning signals of the 2017 and 2019 major financial crashes in Bitcoin. Sliding window is used to obtain point cloud datasets from a multidimensional time series (Bitcoin, Ethereum, Litecoin and Ripple). We apply persistent homology to quantify transient loops that appear in multiscale topological spaces, which associated on each point cloud dataset and encode the quantified information in a persistence landscape. Temporal changes in persistence landscapes are measured via their L1-norms. Consequently, a new representative is attained, called L1-norms time series. The L1-norms is associated with indicators: autocorrelation function at lag 1, variance and mean power spectrum at low frequencies to detect the signals. By using Kendall's tau correlation and significance test, significant rising trend events that occur before major financial crashes in Bitcoin are defined as the signals. A threshold is determined to scan entire data and record all the significant rising trend events. Lastly, we compare L1-norms with residuals time series, which is another representative obtained from de-trending approach. Our result portrays that autocorrelation function at lag 1 and variance of the L1-norms successfully detect early warning signals before the 2017 and 2019 major financial crashes. However, variance of the L1-norms is better since it able to signal another 2018 major financial crash. For the residuals, no early warning signals are detected. Hence, persistent homology provides a better representative than de-trending approach. Overall, persistent homology is a promising method to detect early warning signals of major financial crashes in Bitcoin.
Haya R. Hasan, Khaled Salah, Raja Jayaraman, Junaid Arshad · 7 authors
COVID-19 has emerged as a highly contagious disease which has caused a devastating impact across the world with a very large number of infections and deaths. Timely and accurate testing is paramount to an effective response to this pandemic as it helps identify infections and therefore mitigate (isolate/cure) them. In this paper, we investigate this challenge and contribute by presenting a blockchain-based solution that incorporates self-sovereign identity, re-encryption proxies, and decentralized storage, such as the interplanetary file systems (IPFS). Our solution implements digital medical passports (DMP) and immunity certificates for COVID-19 test-takers. We present smart contracts based on the Ethereum blockchain written and tested successfully to maintain a digital medical identity for test-takers that help in a prompt trusted response directly by the relevant medical authorities. We reduce the response time of the medical facilities, alleviate the spread of false information by using immutable trusted blockchain, and curb the spread of the disease through DMP. We present a detailed description of the system design, development, and evaluation (cost and security analysis) for the proposed solution. Since our code leverages the use of the on-chain events, the cost of our design is almost negligible. We have made our smart contract codes publicly available on Github.
The potential of blockchain technology is immense and is currently regarded as a new technological trend with a rapid growth rate. Blockchain platforms like Bitcoin are public, open, and permission-less. They are also decentralized, immutable, and append-only ledger; those ledgers can store any type of data and are shared among all the participants of the network. These platforms provide a high degree of anonymity for their users’ identity and full transparency of the activities recorded on the ledger while simultaneously ensuring data security and tamper-resistance. All nodes on the network collectively work to validate the same set of data and to achieve group consensus. Blockchain platforms like Ethereum have the ability to develop smart contracts and embed business logic. This allows the use of blockchain beyond cryptocurrency as a business management solution. Besides the issues of scalability and the expensive nature of most blockchain systems, many attributes of traditional public blockchain are not desirable in a business or enterprise context such as anonymity, full transparency, and permissionless. Permissioned blockchain platforms like Hyperledger Fabric are designed and built with enterprise and business in mind, retaining the desirable qualities of blockchain for enterprise while replacing the qualities of blockchain that are undesirable for the enterprise. In this paper, we present a comprehensive review on the Hyperledger enterprise blockchain technologies.
Blockchain Technology Applications and Security
IoT and Edge/Fog Computing
Advanced Steganography and Watermarking Techniques
Bruno Rodrigues, Trendafilov Spasen, Eder J. Scheid, Burkhard Stiller
Distributed Denial-of-Service (DDoS) attacks remains as one of the major causes of concerns for service providers around the world. This paper introduces SC-FLARE, a Smart Contract (SC) based cooperative signaling protocol built on top of a Ethereum Proof-of-Authority Blockchain (BC) for the sharing of attack information, the exchange of incentives, and the tracking of reputation in a fully distributed and automated fashion. By making use of BC and SC, SC-FLARE provide the required collaborative platform without the burden to maintain, design, and develop special registries and gossip protocols for a cooperative defense.
Blockchain technologies enable decentralized applications (DApps) that run on distributed infrastructures without any central authority. All transactions for communication and data storage are public and can be verified by all participants. DApps interacting with a smart contract typically require client-side code, which is not part of the smart contract, and therefore do not hold the same verifiability properties. Following the vision of a verifiable DApp, we propose SmartDHX, a Diffie-Hellman key exchange (DHKE) scheme, fully implemented as a smart contract. That is, SmartDHX communicates only via the Ethereum blockchain and provides both backend and client-side code with the smart contract. The application code can therefore be verified and deployed without external trust requirements. By executing DHKE on-chain, we gain a number of properties, including asynchronicity as well as message integrity and authenticity. We generalize the two-party SmartDHX to emphasize that our approach is able to handle complex cryptographic protocols. In our analysis, we expose an efficiency tradeoff when executed on chain. In particular, we provide a proof-of-concept implementation and analyze the runtime and transaction fees. Since DHKE is used by many cryptographic algorithms, SmartDHX contributes a fundamental building block in the domain of DApps.
Purpose Cryptocurrency markets are notoriously noisy, but not all markets might behave in the exact same way. Therefore, the aim of this paper is to investigate which one of the cryptocurrency markets contributes the most to the common volatility component inherent in the market. Design/methodology/approach The paper extracts each of the cryptocurrency's markets' latent volatility using a stochastic volatility model and, subsequently, models their dynamics in a fractionally cointegrated vector autoregressive model. The authors use the refinement of Lien and Shrestha (2009, J. Futures Mark) to come up with unique Hasbrouck (1995, J. Finance) information shares. Findings The authors’ findings indicate that Bitfinex is the leading market for Bitcoin and Ripple, while Bitstamp dominates for Ethereum and Litecoin. Based on the dominant market for each cryptocurrency, the authors find that the volatility of Bitcoin explains most of the volatility among the different cryptocurrencies. Research limitations/implications The authors’ findings are limited by the availability of the cryptocurrency data. Apart from Bitcoin, the data series for the other cryptocurrencies are not long enough to ensure the precision of the authors’ estimates. Originality/value To date, only price discovery in cryptocurrencies has been studied and identified. This paper extends the current literature into the realm of volatility discovery. In addition, the authors propose a discrete version for the evolution of a markets fundamental volatility, extending the work of Dias et al. (2018).
Contracts are obligations that involve multiple parties and stakeholders. Road - Toll collection contracts have certain guidelines and rules for collection of toll tax from vehicles against the use of constructed roads. Representation of such rules for collection of toll taxes using a smart contract, which is a paradigm based on blockchain, will solve some of the drawbacks of current toll collection and management system. The proposed methodology uses the strengths of blockchain to propose a solution to the current toll tax collection system, by ensuring complete transparency between tax payers and collectors and also attempts to curb the malicious collection of taxes from commuters. Blockchain will enable a radical way of approaching transactions as compared to the traditional society approved method where trust is placed on a central third party to carry out transactions. The purpose of this paper is to provide a alternative method of processing toll tax transactions, using ethereum based smart contracts, written in solidity language, to transform traditional desktop applications into blockchain based web application, which perform better, consume lesser resources and are much more secure as compared to the current system.
Additive Manufacturing (AM) is a major advancement in the digitization of manufacturing and production operations. Additive manufacturing uses three dimensional digital design, software and hardware equipment to precisely deposit layered materials for on-demand product manufacturing. The distinct advantages in enabling additive manufacturing includes cost efficiency, reduced time-to-market, flexibility and precise customization. However, several challenges such as trusted traceability, certification for quality compliance, and protecting intellectual property need to be addressed. Blockchain-based distributed ledgers provide tremendous advantages for product traceability and ensure trust among participating stakeholders. In this paper, we propose a blockchain-based solution for product traceability produced using additive manufacturing, guaranteeing secure and trusted traceability, accessibility, and immutability of transactions, and data provenance among supply chain stakeholders. Our proposed solution utilizes Ethereum smart contracts to govern and trace transactions initiated by participants involved in the manufacturing process. Decentralized storage of Inter-Planetary File Systems is used to store and share design files, IoT device records, and additional product specifications. We provide the system architecture, implementation, and detailed algorithms that demonstrate the working principles of our proposed solution for secure AM. Furthermore, we present detailed security and cost analysis of the solution highlighting its efficiency with respect to key security and performance requirements.