Ethereum is a digital asset whose transactions are kept on a decentralized, globally accessible ledger. An Ethereum Blockchain owner's real identity is concealed behind a pseudonym termed an address. ...Because of this, Ethereum is frequently used in illegal activities like gambling and ransomware attacks because it is popularly believed to offer the highest level of anonymity. As a result, it is necessary to categorize the various malicious cybercriminal users' activities and addresses in the Ethereum Blockchain. The Blockchain's public data enables an in-depth analysis. Using supervised machine learning models including linear, non-linear, and ensemble learning models based on malicious and non-malicious activities, the classification of Ethereum Blockchain addresses is carried out in this paper. In this research work, cross-validation accuracy, recall, precision, and f1-score have been employed for the assessment. Findings indicate that linear and non-linear machine learning approaches are superior to ensemble learning for classifying Ethereum Blockchain addresses. The results also show that it is possible to discover the Ethereum Blockchain addresses of malicious users.
An increasing number of investors are active on Ethereum, resulting in numerous transactions. These historical transactions can be applied to complete contract testing. For example, it can be used ...for gas optimization or contract repair to verify that improved contracts meet expectations. Most existing methods deploy private chains to use non-real transactions for contract verification instead of actual historical transactions on the Ethereum mainnet. The challenge of using actual historical transactions for verification is that Ethereum only records the latest state of the account and cannot restore the execution of historical transactions. Due to contract code changes in contract gas optimization, contract defect repair, and other scenarios, we need to test the execution of the contract code before and after the change. However, existing tools cannot customize and modify historical transactions for testing purposes. Therefore, we propose an efficient transaction replay platform, EthReplayer , which can not only replay the historical transactions of Ethereum quickly and faithfully but also realize the modification of transactions to achieve the purpose of testing with actual transactions. Experimental results show that our replay speed is 1.5 times the fastest available, and it only takes 29,594 seconds to replay 1,200 million blocks. In addition, it is applied to contract repair verification, gas optimization verification, and gas estimation, and the results prove the effectiveness of EthReplayer .
An integrated identity is a centralized identifier that makes it possible for customers to get access to a variety of business services from a single network. The risks and assaults include identity ...leaks, centralized management, auditing restrictions, and lengthy breach investigation procedures. The article presents a technique for creating a blockchain-based, integrated identification system in a marketplace by automating and decentralizing the creation and auditing of strong and secure attributes. When individuals engage in market transactions, they act as nodes in a distributed blockchain network, contributing to the development of federated identities. Using a single federated identity, members of this network are able to use any of the participating companies' services. In this, IoT sensors and wearables can automatically log real-time data for you while identifying patterns and flagging problems. The total transparency of all blockchain transactions provides participants the ability to see which services they're using and their users the ability to track the usage of their identities. To test the proposed architecture, implementation done on a public blockchain and a permissioned blockchain (Ethereum and Hyperledger Fabric).
Data leakage in electronic health records (EHRs) could result in the compromise of patient privacy (e.g. medical conditions). Generally most data in EHRs remain unchanged once they are uploaded to ...the system; thus, blockchain can be potentially used to facilitate the sharing of such data. Different participating medical organizations and individuals (e.g. medical practitioners, hospitals, medical labs and insurance companies) can then access EHRs stored on the blockchain with a higher level of confidence. In this paper, a blockchain based searchable encryption scheme for EHRs is proposed. The index for EHRs is constructed through complex logic expressions and stored in the blockchain, so that a data user can utilize the expressions to search the index. As only the index is migrated to the blockchain to facilitate propagation, the data owners have full control over who can see their EHRs data. The use of blockchain technology ensures the integrity, anti-tampering, and traceability of EHRs’ index. Finally, the performance of the proposed scheme is evaluated from two aspects, namely in terms of the overhead for extracting the document IDs from EHRs and the overhead associated with conducting transactions on smart contract in Ethereum.
•Blockchain based searchable encryption for electronic health record sharing.•File encryption, index construction, transaction generation and searching.•Designated smart contract in blockchain to facilitate monetary rewarding.
•A novel scheme is proposed for IoT-based healthcare systems to generate and maintain medical certificates.•The proposed blockchain system ensures the security of medical certificates.•In the ...proposed scheme, the Merkle root hash of the medical certificate is maintained with a unique transaction identity.•Experimental results prove the efficiency of the proposed scheme over the existing schemes.
Nowadays, blockchain technology is one of the advanced technologies to ensure the security of users’ sensitive or confidential data. Blockchain technology plays a vital role in various applications like artificial intelligence, supply chain, cloud computing, the healthcare sector, and many more. It helps the healthcare domain to get benefitted from its many advanced features, such as confidentiality, decentralization, security, and privacy. Also, the Internet of Things (IoT) devices connect with the healthcare systems, and the healthcare sector application software further communicates with the IT industry. The blockchain-based IoT systems have significantly impacted the healthcare sector by enhancing security, privacy, transparency, and efficiency, providing better business opportunities. Moreover, traditional healthcare systems face severe security and privacy problems, such as phishing, masquerades, identity theft, and many others. Thus, a secure blockchain-based Proposed Application (PA) is designed to generate, maintain, and validate healthcare certificates. The PA acts as a communication medium between the backend blockchain network and application entities like hospitals, patients, doctors, and IoT devices to create and verify medical certificates. It also ensures various security features, namely confidentiality, authentication, and access control, using the concept of smart contracts. The comparative and performance analysis of the proposed work shows that it provides a more effective solution than the existing schemes.
•We utilize the COVID-19 pandemic announcement as the setting to test the safe-haven properties of Bitcoin and Ethereum.•Bitcoin and Ethereum exhibit short-term safe-haven properties.•Ethereum is ...potentially a better safe-haven than Bitcoin.•However, both cryptocurrencies exhibit high volatilities.
Utilizing the WHO COVID-19 pandemic statement, we test Bitcoin and Ethereum as safe-havens for stocks. We find that the two largest cryptocurrencies are suitable as short-term safe-havens. The DCC and cDCC results show that their daily returns tend to correlate with S&P500 return negatively during the pandemic. The regression results also robustly support the safe-haven features and uncover that Ethereum is possibly a better safe-haven than Bitcoin. However, we note that both coins exhibit high volatilities. Before (during) the pandemic daily volatilities of Bitcoin, Ethereum, gold, and the S&P500 are 3.44% (9.11%), 4.34% (10.96%), 0.89% (2.19%), and 1.27% (6.07%), respectively.
The increasing complexity of cloud computing has prompted a greater emphasis on protecting the privacy, integrity, and security of data stored and processed in the cloud. Data privacy is safeguarded ...through access control, but existing models such as Role Based Access Control (RBAC) and Attribute Based Access Control (ABAC) rely on a centralized server. If this server is compromised, it poses significant risks to data security. To address this issue, there is a need for Distributed ABAC (DABAC) system for OpenStack services based on blockchain. The unique features of blockchain enables access control systems which ensures data integrity and privacy. Additionally, blockchain offers a level of transparency for both the resource owner and a user. In this work, we propose a smart contract based ABAC system. We implemented the proposed work using an Ethereum blockchain and OpenStack cloud. Furthermore, we evaluated two consensus algorithms for scalability analysis of DABC mechanism. The results demonstrate that DABAC performs better than ABAC in ensuring fine-grade access control with proof of stake consensus algorithm providing better scalability.
IoTs are integrated, interconnected concepts of things or objects in our surroundings, with an essence of virtualization. The interconnectivity of the business world, health environments, smart home ...devices, and daily use gadgets takes place through the networks based on cloud infrastructure which is not restricted to jurisdictional, geographic, and national boundaries. However, the light-weight IoT devices come with a limited storage and processing capacity. Due to this limitation, the need for separate data storage arises so that data can be utilized in the future. These third-party storage services are provided at the cost of a user’s privacy. Furthermore, the storage relies on a centralized database which is more open to attack due to its single point security breach chances. Furthermore, present IoT data is not trustworthy in the external environment, as data manipulation is lacking when data is shared with other parties. To overcome the above-mentioned limitations of IoT, the emerging secure decentralized storage technology; Blockchain, have begun to abandon the significant impact in the IoT with the enhancement of security and incorporating a large number of devices in the today’s ecosystems. In this paper, we have performed a comprehensive literature review to show how well blockchain has transformed the smart environments connected with IoT sensors and the underlying issues for its adaptation. Further, a well-organized taxonomy is presented by highlighting the strengths, weaknesses, opportunities, and threats (SWOT) of blockchain based IoT environment. In addition to that, we have clearly presented the verities of blockchain applications such as bitcoin (earlier cryptocurrency used in blockchain) or ethereum (establish smart contracts) based works and pinpoint the necessities and security challenges. Moreover, we have highlighted the essential implementation requirements of blockchain in the IoTs. This paper is also equipped with a state-of-the-art framework of IoT while adopting security features and decentralized storage requirements of the blockchain. In the end, we have presented insightful challenges need to be addressed to obtain efficient, secure, and effective communication goals and to provide private and secure services for users as per their requirements.
•In this paper, we have performed a comprehensive literature review to show how well blockchain has transformed the smart environments connected with IoT sensors and the underlying security issues for its adaptation.•A well-organized taxonomy is presented by highlighting the strengths, weaknesses, opportunities, and threats (SWOT) of blockchain based IoT environment.•We have compared existing blockchain applications such as bitcoin (earlier cryptocurrency used in blockchain) or ethereum (establish smart contracts) based works and pinpoint the necessities and security challenges for IoTs.•We have highlighted the essential implementation requirements of blockchain in the IoTs.•A state-of-the-art framework of IoT while adopting security features and decentralized storage requirements of the blockchain is presented.•Last but not least, we have presented insightful security challenges need to be addressed in adaptation of blockchains in IoTs.
A developing field of interest for the distributed systems and applied cryptography communities is that of smart contracts: self-executing financial instruments that synchronize their state, often ...through a blockchain. One such smart contract system that has seen widespread practical adoption is Ethereum, which has grown to a market capacity of 100 billion USD and clears an excess of 500,000 daily transactions. Unfortunately, the rise of these technologies has been marred by a series of costly bugs and exploits. Increasingly, the Ethereum community has turned to formal methods and rigorous program analysis tools. This trend holds great promise due to the relative simplicity of smart contracts and bounded-time deterministic execution inherent to the Ethereum Virtual Machine (EVM). Here we present KEVM, an executable formal specification of the EVM's bytecode stack-based language built with the K Framework, designed to serve as a solid foundation for further formal analyses. We empirically evaluate the correctness and performance of KEVM using the official Ethereum test suite. To demonstrate the usability, several extensions of the semantics are presented. and two different-language implementations of the ERC20 Standard Token are verified against the ERC20 specification. These results are encouraging for the executable semantics approach to language prototyping and specification.
Bubbles and spikes in cryptocurrency prices increase considerably the risk on investments in these assets. In the traditional time series literature bubbles are viewed as nonstationary and ...non-estimable components of a process. In this paper, we adopt a different approach and consider the bubbles as inherent features of a strictly stationary causal-noncausal (mixed) Vector Autoregressive (VAR) process. This approach allows us to model and estimate the common bubbles and spikes in cryptocurrency prices. It also provides us linear combinations of cryptocurrencies that eliminate common bubbles analogously to the cointegrating vectors eliminating common trends in unit root processes. They are used to build cryptocurrency portfolios immune to the risk of common bubbles that ensure stable investment strategies. The mixed VAR model is estimated from the US Dollar prices of Bitcoin, Ethereum, Ripple, and Stellar over the period 2017–2019. We document the common bubbles and illustrate the behaviour of bubble-free portfolios.
•We examine the US Dollar prices of four large cap cryptocurrencies.•Bitcoin, Ether, Ripple and Stellar have common bubbles and spikes between 2017 and 2019.•Cryptocurrency prices follow a causal-noncausal (mixed) Vector Autoregressive model.•We reveal linear combinations of cryptocurrency that eliminate common bubbles and spikes.•The bubble-free combinations of cryptocurrency provide portfolios of stable investments.
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