Blockchain Papers

Ender Demir, Mehmet Hüseyin Bilgin, Gökhan Karabulut, Aslı Cansın Doker

No abstract is available for this record.

Jay Patel, Vasu Kalariya, Pushpendra Parmar, Sudeep Tanwar · 6 authors

Over the past few years, with the advent of blockchain technology, there has been a massive increase in the usage of Cryptocurrencies. However, Cryptocurrencies are not seen as an investment opportunity due to the market's erratic behavior and high price volatility. Most of the solutions reported in the literature for price forecasting of Cryptocurrencies may not be applicable for real-time price prediction due to their deterministic nature. Motivated by the aforementioned issues, we propose a stochastic neural network model for Cryptocurrency price prediction. The proposed approach is based on the random walk theory, which is widely used in financial markets for modeling stock prices. The proposed model induces layer-wise randomness into the observed feature activations of neural networks to simulate market volatility. Moreover, a technique to learn the pattern of the reaction of the market is also included in the prediction model. We trained the Multi-Layer Perceptron (MLP) and Long Short-Term Memory (LSTM) models for Bitcoin, Ethereum, and Litecoin. The results show that the proposed model is superior in comparison to the deterministic models.

Thomas Conlon, Shaen Corbet, Richard McGee

The COVID-19 pandemic provided the first widespread bear market conditions since the inception of cryptocurrencies. We test the widely mooted safe haven properties of Bitcoin, Ethereum and Tether from the perspective of international equity index investors. Bitcoin and Ethereum are not a safe haven for the majority of international equity markets examined, with their inclusion adding to portfolio downside risk. Only investors in the Chinese CSI 300 index realized modest downside risk benefits (contingent on very limited allocations to Bitcoin or Ethereum). As Tether successfully maintained its peg to the US dollar during the COVID-19 turmoil, it acted as a safe haven investment for all of the international indices examined. We caveat the latter findings with a warning that Tether's dollar peg has not always been maintained, with evidence of impaired downside risk hedging properties earlier in our sample.

Teppei Sato, Mitsuyoshi Imamura, Kazumasa Omote

No abstract is available for this record.

Purathani Praitheeshan, Lei Pan, Robin Doss

No abstract is available for this record.

David Carl, Christian Ewerhart

For users of the Ethereum network, the gas price is a crucial parameter that determines how swiftly the decentralized consensus protocol confirms a transaction. This paper studies the statistics of the Ethereum gas price. We start with some conceptual discussion of the gas price notion in view of the actual transaction-selection strategies used by Ethereum miners. Subsequently, we provide the descriptive statistics of what we call the threshold gas price. Finally, we identify and estimate a seasonal ARIMA (SARIMA) model for predicting the hourly median of the threshold gas price.

Yizhong Liu, Yiming Hei, Tongge Xu, Jianwei Liu

Ethereum accelerates the transaction process through a quicker block creation design. Since the time interval between the generation of blocks is very short (about 15s), block propagation time in an inefficient network is not negligible compared with the block time interval. This lead to the production of a large number of orphan blocks. In order to solve the security problems that may be caused by the orphan block and improve the transaction processing efficiency, Ethereum introduces the uncle block mechanism, i.e., an orphan block may get part of minted reward if it gets a reference by a regular block. In this paper, we show the weakness of the uncle block mechanism. Firstly, we describe the specific differences of Ethereum selfish and stubborn mining in every state from the ones in Bitcoin. Secondly, we simulate possible attacks, and the results show that the Ethereum selfish and stubborn mining strategies not only increase the reward of an attacker but also decrease the security threshold. The security threshold refers to the proportion of the attacker's computational power that needs to be achieved in order to obtain a higher reward than he should. In a practical network congestion rate, the security threshold are weakened to 0.129 and 0.216 against the Lead stubborn mining strategy and the original selfish mining strategy, respectively. When the congestion rate is rising, the reward is increasing and the threshold is decreasing. Thirdly, possible strategies are evaluated to find out the optimal one in different settings. Fourthly, we also extend the evaluation by combining three eclipse attack strategies with selfish or stubborn mining. Most of combinations bring more advantages to an attacker than a single strategy.

Daejun Park, Yi Zhang, Grigore Roşu

We report our experience in the formal verification of the deposit smart contract, whose correctness is critical for the security of Ethereum 2.0, a new Proof-of-Stake protocol for the Ethereum blockchain. The deposit contract implements an incremental Merkle tree algorithm whose correctness is highly nontrivial, and had not been proved before. We have verified the correctness of the compiled bytecode of the deposit contract to avoid the need to trust the underlying compiler. We found several critical issues of the deposit contract during the verification process, some of which were due to subtle hidden bugs of the compiler.

António Miguel Rosado da Cruz, Francisco Javier Nieto De Santos, Paulo Mendes, Estrela Ferreira Cruz

No abstract is available for this record.

Sam M. Werner, Paul J. Pritz, Daniel Pérez

In the Ethereum network, miners are incentivized to include transactions in a block depending on the gas price specified by the sender. The sender of a transaction therefore faces a trade-off between timely inclusion and cost of his transaction. Existing recommendation mechanisms aggregate recent gas price data on a per-block basis to suggest a gas price. We perform an empirical analysis of historic block data to motivate the use of a predictive model for gas price recommendation. Subsequently, we propose a novel mechanism that combines a deep-learning based price forecasting model as well as an algorithm parameterized by a user-specific urgency value to recommend gas prices. In a comprehensive evaluation on real-world data, we show that our approach results on average in costs savings of more than 50% while only incurring an inclusion delay of 1.3 blocks, when compared to the gas price recommendation mechanism of the most widely used Ethereum client.

Imran Ashraf, Xiaoxue Ma, Bo Jiang, W. K. Chan

Ethereum is a kind of blockchain platform where developers may develop and run programs called smart contracts. It inherently relies on gas consumption within a specified allowance to constrain code execution, making every instruction along an execution path to be a location for raising an exception. In this paper, we present GasFuzzer, the first work in exploring the effects of gas allowance manipulation to expose gas-oriented exception security vulnerabilities. GasFuzzer consists of two phases. The first phase introduces a gas-greedy strategy to favor transactions having higher gas consumption for mutation to obtain test transactions with different gas consumptions. The second phase introduces a novel notion of fractional gas consumption coverage and a novel gas-leveling strategy. It applies them to mutate the gas allowances of some of these transactions resulting in the highest gas consumptions produced in the first phase followed by applying these allowance-mutated transactions together with those which remained non-mutated to fuzz test the smart contract. We report an evaluation of GasFuzzer via an experiment on 3170 real-world smart contracts deployed on the public Ethereum Blockchain between October 2017 and July 2019. The findings show that GasFuzzer with gas-greedy strategy can detect more Exceptions Disorder kind of security vulnerabilities (7 more cases) than the previous state-of-the-art black-box fuzzer, and GasFuzzer with gas-leveling strategy and gas coverage criterion can detect 6 additional cases of Exceptions Disorder security vulnerabilities, which is significant.

Santeri Paavolainen, Christopher Carr

Ethereum is a decentralized blockchain, known as being the second most popular public blockchain after Bitcoin. Since Ethereum is decentralised the canonical state is determined by the Ethereum network participants via a consensus mechanism without a centralized coordinator. The network participants are required to evaluate every transaction starting from the genesis block, which requires a large amount of network, computing, and storage resources. This is impractical for many devices with either limited computing resources or intermittent network connectivity. To overcome this drawback Ethereum defines a light client protocol where the light client fetches the blockchain state from a node operating as a light protocol server. Light clients are unable to maintain blockchain state internally, and as a consequence can only perform partial validation on blocks. Thus they rely on the light server for full block validation and to provide the updated blockchain state. Light clients connect to multiple light servers to mitigate the risk of relying on a single potentially dishonest server. Ethereum light clients are known to suffer from a probabilistic security model, but they are widely assumed to be secure under normal operating conditions. In fact, the implicit security assumptions of light clients have not been formally characterised in the literature. We present and analyse the probabilistic security guarantees under three different adversarial scenarios. The results show that for any adversary that is able to manipulate the network, the security assurances provided by the light protocol are severely impacted, and in some cases entirely lost. These results clearly demonstrate that the assumption of normal operating conditions is insufficient to justify the security assumptions of light clients. Our work also provides insight to the security of light clients under different security parameters, allowing light client implementers to more accurately understand the potential security trade-offs.

Vatsal Patel, Lei Pan, Sutharshan Rajasegarar

No abstract is available for this record.

Umair Khan, Zhang Yong An, Azhar Imran

The idea of a shared economy becomes one of the companies as an enterprise type. Especially with the advanced development of digital smart devices and the internet, several forms of the mutual economy have been advanced in accord with the need for sharing of separate income. Shareable commodity and digital content are also seeking to utilize. When digital content is used as a sharing economy, various possible threats may arise in the course of transactions, the potential for theft, alteration, and hacking of contents. This paper presents a comprehensive overview of the security and privacy of Blockchain. Blockchain promise transparent, tamper-proof and secure systems that can enable novel solutions, especially when combined with smart contracts. In this research, we proposed a content protection and transaction method using Blockchain Ethereum Technology. The encryption algorithm is incorporated in proposed system to make transparent transactions and it is also implemented on content itself to prevent from smart forgery and hacking. The experimental results signify that the proposed method has strong potential to enhance transactions transparency by minimizing the security threats in digital content transactions.

Yitao Li, Umar Islambekov, Cüneyt Gürcan Akçora, Ekaterina Smirnova · 6 authors

The Blockchain technology and, in particular blockchain-based cryptocurrencies, offer us information that has never been seen before in the financial world. In contrast to fiat currencies, all transactions of crypto-currencies and crypto-tokens are permanently recorded on distributed ledgers and are publicly available. This allows us to construct a transaction graph and to assess not only its organization but to glean relationships between transaction graph properties and crypto price dynamics. The goal of this paper is to facilitate our understanding on horizons and limitations of what can be learned on crypto-tokens from local topology and geometry of the Ethereum transaction network whose even global network properties remain scarcely explored. By introducing novel tools based on Topological Data Analysis and Functional Data Depth into Blockchain Data Analytics, we show that Ethereum network (one of the most popular blockchains for creating new crypto-tokens) can provide critical insights on price changes of crypto-tokens that are otherwise largely inaccessible with conventional data sources and traditional analytic methods.

Praveen M. Dhulavvagol, Vijayakumar H Bhajantri, Shashikumar G. Totad

Blockchain technology is evolving and revolutionizing the IT industry with better security, efficiency, and resilience. Blockchain technology is being used in many applications majorly in cryptocurrencies and bitcoin applications. Verified transactions which make a block and group of such transactions or blocks are immutable making the blockchain more secured and reliable. Blockchain achieves decentralization of power, trust, and secured of being hacked, which solves major problems or issues with the current systems. Ethereum, the most widely used blockchain platform because of its unlimited block size. Many complex problems with smart contracts can be implemented with Ethereum and the eradication of third party organizations interfering in transactions helps solving the issues of financial crisis and it is easy to implement compared to other blockchain technologies. There are certain limitations/issues in processing large number of transactions due to lack of speed in processing the transactions. Ethereum Blockchain code will be executed by different clients with varying speed and the performance level will be different. The goal of this paper is to understand Ethereum transactions and perform the comparative analysis of Geth and Parity ethereum clients on the private blockchain. In this paper, a private blockchain network is setup where the nodes will share the data among peer nodes or blocks within the network. Using this network setup a democracy voting application is developed which makes use of the blockchain to store and process the data, smart contracts are deployed to execute the transactions. Performance analysis of the two most popular ethereum clients Geth and Parity is carried out considering time, consistency and scalability parameters. Results interpret that the overall transactions are 91% on average faster in parity client as compared to Geth client.

Kentaroh Toyoda, Koji Machi, Yutaka Ohtake, Allan N. Zhang

Private Ethereum blockchain-based systems are demanded in many industry sectors. However, the throughput performance of these systems does not meet their expectations. Many researchers have analyzed the performance of private blockchains, but their studies have failed to analyze root causes. In this paper, we perform a deep function-level bottleneck analysis for the private Ethereum blockchain. As the Ethereum client application is developed with golang, we leverage pprof, which is a resource-profiling tool for golang, and custom golang functions to measure the time taken by functions. To easily configure parameters and conduct our test, we code a shell script that automates the building process of a private Ethereum blockchain with docker containers. We conducted a series of experiments and identified the bottleneck function that is called every time a transaction arrives at an Ethereum node. In addition, we also found that the multi-threading is not well utilized, meaning that there is much room for improvement.

William Metcalfe

On February 28, 2012, an 18-year-old high school student wrote “If BitcoinBitcoin is to achieve mainstream success, it cannot stop at the limited crowds of InternetInternet geeks, libertarians, and privacy advocates that it is hitting now, and it must find some way to attract the mainstream public” (Buterin in Bitcoin adoption opportunity: teenagers, 2012).

Emanuel Palm, Ulf Bodin, Olov Schelén

The rise of distributed ledger technologies, such as R3 Corda, Hyperledger Fabric and Ethereum, has lead to a surge of interest in digitalizing different forms of contractual cooperation. By allowing for ledgers of collaboration-critical data to be reliably maintained between stakeholders without intermediaries, these solutions might enable unprecedented degrees of automation across organizational boundaries, which could have major implications for supply chain integration, medical journal sharing and many other use cases. However, these technologies tend to break with prevailing business practices by relying on code-as-contracts and distributed consensus algorithms, which can impose disruptive requirements on contract language, cooperation governance and interaction privacy. In this paper, we show how our Exchange Network architecture could be applied to avoid these disruptors. To be able to reason about the adequacy of our architecture, we present six requirements for effective contractual collaboration, which notably includes negotiable terms and effective adjudication. After outlining the architecture and our implementation of it, we describe how the latter meets our requirements by facilitating (1) negotiation, (2) user registries, (3) ownership ledgers and (4) definition sharing, as well as by only replicating ledgers between stakeholder pairs. To show how our approach compares to other solutions, we also consider how Corda, Fabric and Ethereum meet our requirements. We conclude that digital negotiation and ownership could replace many proposed uses of code-as-contracts for better compatibility with current contractual practices, as well as noting that distributed consensus algorithms are not mandatory for digital cooperation.

Florian Gräbe, Niclas Kannengießer, Sebastian Lins, Ali Sunyaev

Distributed Ledger Technology (DLT) enables a new way of inter-organizational collaboration via a shared and distributed infrastructure. Meanwhile, there is plenty of DLT designs (e.g., Ethereum, IOTA), which differ in their capabilities to meet use case requirements. A structured comparison of DLT designs is required to support the decision for an appropriate DLT design. However, existing criteria and processes are abstract or not suitable for an in-depth comparison of DLT designs. We select and operationalize DLT characteristics relevant for a comprehensive comparison of DLT designs. Furthermore, we propose a comparison process, which enables the structured comparison of a set of DLT designs according to application requirements. The proposed process is validated with a use case analysis of three use cases. We contribute to research and praxis by introducing ways to operationalize DLT characteristics and generate a process to compare different DLT designs accordingly to their suitability in a use case.

Mirko Zichichi, Stefano Ferretti, Gabriele D’Angelo

Data are becoming the cornerstone of many businesses and entire systems infrastructure. Intelligent Transportation Systems (ITS) are no different. The ability of intelligent vehicles and devices to acquire and share environmental measurements in the form of data is leading to the creation of smart services for the benefit of individuals. In this paper, we present a system architecture to promote the development of ITS using distributed ledgers and related technologies. Thanks to these, it becomes possible to create, store and share data generated by users through the sensors on their devices or vehicles, while on the move. We propose an architecture based on Distributed Ledger Technologies (DLTs) to offer features such as immutability, traceability and verifiability of data. IOTA, a promising DLT for IoT, is used together with Decentralized File Storages (DFSes) to store and certify data (and their related metadata) coming from vehicles or by the users' devices themselves (smartphones). Ethereum is then exploited as the smart contract platform that coordinates the data sharing through access control mechanisms. Privacy guarantees are provided by the usage of distributed key management systems and Zero Knowledge Proof. We provide experimental results of a testbed based on real traces, in order to understand if DLT and DFS technologies are ready to support complex services, such as those that pertain to ITS. Results clearly show that, while the viability of the proposal cannot be rejected, further work is needed on the responsiveness of DLT infrastructures.

Niclas Kannengießer, Michelle Pfister, Malte Greulich, Sebastian Lins · 5 authors

Since the emergence of blockchain in 2008, today, we see a kaleidoscopic variety of applications built on distributed ledger technology (DLT), including applications for financial services, healthcare, or the Internet of Things. Yet, each application comes with specific requirements for DLT characteristics (e.g., high throughput, scalability). However, trade-offs between DLT characteristics restrict the development of a DLT design (e.g., Ethereum, IOTA) that fits all use cases’ requirements simultaneously. Consequently, separated DLT designs emerged, each specialized to suite dedicated application requirements. To enable the development of more powerful applications on DLT, such DLT islands must be bridged. However, knowledge on cross-chain technology (CCT) is scattered across scientific and practical sources. Therefore, we examine this diverse body of knowledge and provide comprehensive insights into CCT by synthesizing underlying characteristics, evolving patterns, and use cases. Our findings resolve existing contradictions in the literature and provide avenues for future research in an emerging scientific field.

Eman M. Abou-Nassar, Abdullah M. Iliyasu, Passent Elkafrawy, Oh-Young Song · 6 authors

Today, internet and device ubiquity are paramount in individual, formal and societal considerations. Next generation communication technologies, such as Blockchains (BC), Internet of Things (IoT), cloud computing, etc. offer limitless capabilities for different applications and scenarios including industries, cities, healthcare systems, etc. Sustainable integration of healthcare nodes (i.e. devices, users, providers, etc.) resulting in healthcare IoT (or simply IoHT) provides a platform for efficient service delivery for the benefit of care givers (doctors, nurses, etc.) and patients. Whereas confidentiality, accessibility and reliability of medical data are accorded high premium in IoHT, semantic gaps and lack of appropriate assets or properties remain impediments to reliable information exchange in federated trust management frameworks. Consequently, We propose a Blockchain Decentralised Interoperable Trust framework (DIT) for IoT zones where a smart contract guarantees authentication of budgets and Indirect Trust Inference System (ITIS) reduces semantic gaps and enhances trustworthy factor (TF) estimation via the network nodes and edges. Our DIT IoHT makes use of a private Blockchain ripple chain to establish trustworthy communication by validating nodes based on their inter-operable structure so that controlled communication required to solve fusion and integration issues are facilitated via different zones of the IoHT infrastructure. Further, C# implementation using Ethereum and ripple Blockchain are introduced as frameworks to associate and aggregate requests over trusted zones.

Affaf Shahid, Ahmad Almogren, Nadeem Javaid, Fahad Ahmed Al-Zahrani · 6 authors

Supply chains are evolving into automated and highly complex networks and are becoming an important source of potential benefits in the modern world. At the same time, consumers are now more interested in food product quality. However, it is challenging to track the provenance of data and maintain its traceability throughout the supply chain network. The traditional supply chains are centralized and they depend on a third party for trading. These centralized systems lack transparency, accountability and auditability. In our proposed solution, we have presented a complete solution for blockchain-based Agriculture and Food (Agri-Food) supply chain. It leverages the key features of blockchain and smart contracts, deployed over ethereum blockchain network. Although blockchain provides immutability of data and records in the network, it still fails to solve some major problems in supply chain management like credibility of the involved entities, accountability of the trading process and traceability of the products. Therefore, there is a need of a reliable system that ensures traceability, trust and delivery mechanism in Agri-Food supply chain. In the proposed system, all transactions are written to blockchain which ultimately uploads the data to Interplanetary File Storage System (IPFS). The storage system returns a hash of the data which is stored on blockchain and ensures efficient, secure and reliable solution. Our system provides smart contracts along with their algorithms to show interaction of entities in the system. Furthermore, simulations and evaluation of smart contracts along with the security and vulnerability analyses are also presented in this work.