Marten Sigwart, Michael Borkowski, Marco Peise, Stefan Schulte · 5 authors
As more and more applications and services depend on data collected and provided by Internet of Things (IoT) devices, it is of importance that such data can be trusted. Data provenance solutions together with blockchain technology are one way to make data more trustworthy. However, current solutions do not address the heterogeneous nature of IoT applications and their data. In this work, we identify functional and non-functional requirements for a generic IoT data provenance framework, and conceptualise the framework as a layered architecture. Using a proof-of-concept implementation based on Ethereum smart contracts, data provenance can be realised for a wide range of IoT use cases. Benefits of a generic framework include simplified adoption and a more rapid implementation of data provenance for the IoT.
Recently, graph embedding techniques have been widely used in the analysis of various networks, but most of the existing embedding methods omit the network dynamics and the multiplicity of edges, so it is difficult to accurately describe the detailed characteristics of the transaction networks. Ethereum is a blockchain-based platform supporting smart contracts. The open nature of blockchain makes the transaction data on Ethereum completely public, and also brings unprecedented opportunities for the transaction network analysis. By taking the realistic rules and features of transaction networks into consideration, we first model the Ethereum transaction network as a Temporal Weighted Multidigraph (TWMDG), where each node is a unique Ethereum account and each edge represents a transaction weighted by amount and assigned with timestamp. Then we define the problem of Temporal Weighted Multidigraph Embedding (T-EDGE) by incorporating both temporal and weighted information of the edges, the purpose being to capture more comprehensive properties of dynamic transaction networks. To evaluate the effectiveness of the proposed embedding method, we conduct experiments of node classification on real-world transaction data collected from Ethereum. Experimental results demonstrate that T-EDGE outperforms baseline embedding methods, indicating that time-dependent walks and multiplicity characteristic of edges are informative and essential for time-sensitive transaction networks.
Since the inception of Bitcoin in 2008, cryptocurrencies have played an increasing role in the world of e-commerce, but the recent turbulence in the cryptocurrency market in 2018 has raised some concerns about their stability and associated risks. For investors, it is crucial to uncover the dependence relationships between cryptocurrencies for a more resilient portfolio diversification. Moreover, the stochastic behavior in both tails is important, as long positions are sensitive to a decrease in prices (lower tail), while short positions are sensitive to an increase in prices (upper tail). In order to assess both risk types, we develop in this paper a flexible copula model which is able to distinctively capture asymptotic dependence or independence in its lower and upper tails simultaneously. Our proposed model is parsimonious and smoothly bridges (in each tail) both extremal dependence classes in the interior of the parameter space. Inference is performed using a full or censored likelihood approach, and we investigate by simulation the estimators' efficiency under three different censoring schemes which reduce the impact of non-extreme observations. We also develop a local likelihood approach to capture the temporal dynamics of extremal dependence among two leading cryptocurrencies. We here apply our model to historical closing prices of five leading cryotocurrencies, which share most of the cryptocurrency market capitalizations. The results show that our proposed copula model outperforms alternative copula models and that the lower tail dependence level between most pairs of leading cryptocurrencies -- and in particular Bitcoin and Ethereum -- has become stronger over time, smoothly transitioning from an asymptotic independence regime to an asymptotic dependence regime in recent years, whilst the upper tail has been relatively more stable overall at a weaker dependence level.
Ethereum is an open-source, public, blockchain-based distributed computing platform and operating system featuring smart contract functionality. In this paper, we proposed an Ethereum based eletronic voting (e-voting) protocol, Ques-Chain, which can ensure the authentication can be done without hurting confidentiality and the anonymity can be protected without problems of scams at the same time. Furthermore, the authors considered the wider usages Ques-Chain can be applied on, pointing out that it is able to process all kinds of messages and can be used in all fields with similar needs.
The benefits of blockchain technology are evident in the banking industry as the underlying technology for cryptocurrencies. Recently, research has been focused on novel, non-cryptocurrency uses of blockchain for other industries such as national defense. Application of these technologies in military use cases requires special consideration of the limitations inherent to tactical military operations, namely the network communication technologies. In this work we explore the performance of blockchain technologies on network environments representative of those available in Department of Defense (DoD) tactical operations. Our experimentation with the Ethereum blockchain on a mobile network emulation reveals a series of verbose blockchain network communication protocols as well as a heavy reliance on Transmission Control Protocol (TCP) for block transfer and synchronization that may limit the effectiveness of blockchain on current DoD mobile ad hoc networks.
This study has been undertaken to all the segments and functioning of BlockChain and Cryptocurrency. They have become one of the hottest topics in the tech and finance world. This technology directly affects the financial world. It is safe, secure, and fast and expanding with a predicted rate of 42.8% by 2020. The immense potential this technology holds for future growth gives rise to the concept of BitCoin, Ethereum, etc. There are more than 2000 startups based on BlockChain Technology with a high market inclination.
Νικόλαος Αλεξόπουλος, Emmanouil Vasilomanolakis, Stéphane Le Roux, Steven Rowe · 5 authors
Sophisticated mass attacks, especially when exploiting zero-day vulnerabilities, have the potential to cause destructive damage to organizations and critical infrastructure. To timely detect and contain such attacks, collaboration among the defenders is critical. By correlating real-time detection information (alerts) from multiple sources (collaborative intrusion detection), defenders can detect attacks and take the appropriate defensive measures in time. However, although the technical tools to facilitate collaboration exist, real-world adoption of such collaborative security mechanisms is still underwhelming. This is largely due to a lack of trust and participation incentives for companies and organizations. This paper proposes TRIDEnT, a novel collaborative platform that aims to enable and incentivize parties to exchange network alert data, thus increasing their overall detection capabilities. TRIDEnT allows parties that may be in a competitive relationship, to selectively advertise, sell and acquire security alerts in the form of (near) real-time peer-to-peer streams. To validate the basic principles behind TRIDEnT, we present an intuitive game-theoretic model of alert sharing, that is of independent interest, and show that collaboration is bound to take place infinitely often. Furthermore, to demonstrate the feasibility of our approach, we instantiate our design in a decentralized manner using Ethereum smart contracts and provide a fully functional prototype.
Digitalization revolutionizes all legal areas, including corporate law. The article deals with different impacts of digitalization on communication schemes in corporations, such as virtual general assemblies or communication patterns in board of directors, also encompassing communication with third parties, namely investors. The legal framework for these communication patterns refer not only to corporate but also to media regulations, data protections, as well as capital market law. Digitalization also has an impact on liability of directors: As Big Data and new algorithms improve the information base for decision making of directors they are at the same time obliged to make use of it. On the other hand, IT-security has become one of the main tasks for directors as digitalization of all work flows in enterprises requires necessary IT-security standards in order to avoid existential risks in case of attacks. Furthermore, Blockchain as a new technology enables the secure identification of all kind of transactions, including automatized contracts (so-called smart contracts) which could enhance procedures in corporations. New problems arise concerning the use of Blockchain as an investment form such as DAO Ethereum. Finally, the phenomenon of close cooperation between different partners by using digital work flows and semi-intelligent agents (so-called industry 4.0) is discussed.
We present models that utilize smart contracts and interledger mechanisms to\nprovide decentralized authorization for constrained IoT devices. The models\ninvolve different tradeoffs in terms of cost, delay, complexity, and privacy,\nwhile exploiting key advantages of smart contracts and multiple blockchains\nthat communicate with interledger mechanisms. These include immutably recording\nhashes of authorization information and policies in smart contracts, resilience\nthrough the execution of smart contract code on all blockchain nodes, and\ncryptographically linking transactions and IoT events recorded on different\nblockchains using hash and time-lock mechanisms. The proposed models are\nevaluated on the public Ethereum testnets Rinkeby and Ropsten, in terms of\nexecution cost (gas), delay, and reduction of data that needs to be sent to the\nconstrained IoT devices.\n
The effect of counterfeiting on smart phone sales worldwide is estimated at 184 million units, valued at 45.3 billion EUR or 12.9 % of total sales. The mobile phone counterfeiting, in addition to its economic impact, has serious security, privacy, and even general safety concerns. The proliferation of Smart Phones devices is on the rise, where the number of smart phone devices shipped in 2017 has surpassed 1.5 billion devices and it is has reached around 1.2 billion devices by end of Q3 2018. Most of those devices are attached to different mobile networks operated around the globe, and the challenges arising is how those devices' identities are maintained and verified in addition to how the supply chain actors in smart phones industry can ensure the access to device identity throughout the device life cycle with less control from third parties. Blockchain as a distributed ledger technology positions itself as a suitable candidate to address this challenge. That is mainly attributed to Blockchain's use of cryptographic identifiers, records immutability, and provenance. These features, together, provide a platform to implement the functions of smart phone identity management functions in a global and decentralized environment. This paper presents a the use of a decentralized identity management framework to implement a system for Smart Phone Anti-Counterfeiting that eliminates the need for a central authority and provides the features of identity creation and transfer of ownership, along with the capability of fast and secure reporting of stolen and lost devices that takes effect in the shortest time. The work is implemented using a set of solidity of smart contracts deployed on a private Ethereum Blockchain.
Solidity is an object-oriented and high-level language for writing smart contracts that are used to execute, verify and enforce credible transactions on permissionless blockchains. In the last few years, analysis of smart contracts has raised considerable interest and numerous techniques have been proposed to check the presence of vulnerabilities in them. Current techniques lack traceability in source code and have widely differing work flows. There is no single unifying framework for analysis, instrumentation, optimisation and code generation of Solidity contracts. In this paper, we present SIF, a comprehensive framework for Solidity contract analysis, query, instrumentation, and code generation. SIF provides support for Solidity contract developers and testers to build source level techniques for analysis, understanding, diagnostics, optimisations and code generation. We show feasibility and applicability of the framework by building practical tools on top of it and running them on 1838 real smart contracts deployed on the Ethereum network.
Jiachi Chen, Xin Xia, David Lo, John Grundy · 6 authors
Smart contracts are programs running on a blockchain. They are immutable to change, and hence can not be patched for bugs once deployed. Thus it is critical to ensure they are bug-free and well-designed before deployment. A Contract defect is an error, flaw or fault in a smart contract that causes it to produce an incorrect or unexpected result, or to behave in unintended ways. The detection of contract defects is a method to avoid potential bugs and improve the design of existing code. Since smart contracts contain numerous distinctive features, such as the gas system. decentralized, it is important to find smart contract specified defects. To fill this gap, we collected smart-contract-related posts from Ethereum StackExchange, as well as real-world smart contracts. We manually analyzed these posts and contracts; using them to define 20 kinds of contract defects. We categorized them into indicating potential security, availability, performance, maintainability and reusability problems. To validate if practitioners consider these contract as harmful, we created an online survey and received 138 responses from 32 different countries. Feedback showed these contract defects are harmful and removing them would improve the quality and robustness of smart contracts. We manually identified our defined contract defects in 587 real world smart contract and publicly released our dataset. Finally, we summarized 5 impacts caused by contract defects. These help developers better understand the symptoms of the defects and removal priority.
Renlord Yang, Toby Murray, Paul Rimba, Udaya Parampalli
Ethereum's Gas mechanism attempts to set transaction fees in accordance with the computational cost of transaction execution: a cost borne by default by every node on the network to ensure correct smart contract execution. Gas encourages users to author transactions that are efficient to execute and in so doing encourages node diversity, allowing modestly resourced nodes to join and contribute to the security of the network. However, the effectiveness of this scheme relies on Gas costs being correctly aligned with observed computational costs in reality. In this work, we performed the first large scale empirical study to understand to what degree this alignment exists in practice, by collecting and analyzing Tera-bytes worth of nanosecond-precision transaction execution traces. Besides confirming potential denial-of-service vectors, our results also shed light on the role of I/O in transaction costs which remains poorly captured by the current Gas cost model. Finally, our results suggest that under the current Gas cost model, nodes with modest computational resources are disadvantaged compared to their better resourced peers, which we identify as an ongoing threat to node diversity and network decentralization.
This paper introduces FileTribe, a secure decentralized application for sharing files in closed groups. It employs IPFS, a distributed file system, as its data storage layer, avoiding the pitfalls of centralized storage solutions. Changes to files and group membership are recorded separately on a blockchain, making them irrefutable. A Decentralized Application (Dapp) on top of Ethereum is responsible for user authentication and reaching consensus among group members regarding the state of the group and shared files. File access control is supervised by the members themselves. These features combine to make FileTribe unique in its ability to serve a wide range of safetycritical scenarios, including ones where cloud-based or pure peerto- peer solutions fall short.
With the frantic development of smart contracts on the Ethereum platform, its market value has also climbed. In 2016, people were shocked by the loss of nearly $50 million in cryptocurrencies from the DAO reentrancy attack. Due to the tremendous amount of money flowing in smart contracts, its security has attracted much attention of researchers. In this paper, we investigated several common smart contract vulnerabilities and analyzed their possible scenarios and how they may be exploited. Furthermore, we survey the smart contract vulnerability detection tools for the Ethereum platform in recent years. We found that these tools have similar prototypes in software vulnerability detection technology. Moreover, for the features of public distribution systems such as Ethereum, we present the new challenges that these software vulnerability detection technologies face.
Current swarm robotics systems are not utilized as frequently in surveillance missions due to the limitations of the existing distributed systems' designs. The main limitation of swarm robotics is the absence of a framework for robots to be self-governing, secure, and scalable. As of today, a swarm of robots is not able to communicate and perform tasks in transparent and autonomous ways. Many believe blockchain is the imminent future of distributed autonomous systems. A blockchain is a system of computers that stores and distributes data among all participants. Every single participant is a validator and protector of the data in the blockchain system. The data cannot be modified since all participants are storing and watching the same records. In this thesis, we will focus on blockchain applications in swarm robotics using Ethereum smart contracts because blockchain can make a swarm globally connected and secure. A decentralized application (DApp) is used to deploy surveillance missions. After mission deployment, the swarm uses blockchain to communicate and make decisions on appropriate tasks within Ethereum private networks. We set a test swarm robotics system and evaluate the blockchain for its performance, scalability, recoverability, and responsiveness. We conclude that, although blockchain enables a swarm to be globally connected and secure, there are performance limitations that can become a critical issue.
The censorship attack is ubiquitous in prevailing blockchains, such as Bitcoin and Ethereum, yet has not been resolved well so far. According to known vulnerabilities of different consensus algorithms, censorship attacks can always achieve great benefits at low costs by various means. In this paper, we propose improvements to existing POS and POW algorithms to resolve censorship attacks in two methods. The first method improves the Tendermint consensus mechanism by introducing three new types of messages and an auxiliary role of network nodes. The method can automatically defend against censorship attacks and organize an honest chain. The second method is based on the CasperFFG consensus mechanism and can accurately identify the attackers by evaluating the suspicious scores of all validators. However, an honest validator has to manually choose the honest chain. Theoretical analyses show their effectiveness.
We propose a blockchain-based reseller system that ensures the ownership of the products, prevents multiple selling, and guarantees the transfer of the ownership. The system employs mutual collateral method to prevent any dishonest behavior by both seller and buyer. This system is built on Ethereum blockchain to maintain the public record of transactions and uses ERC-721 tokens to define the traded goods. Sellers must confirm their identity with a valid MetaMask account and pay a first-time registration fee. The smart contract utilizes the OpenZeppelin library's Ownable. sol contract to implement the transfer of ownership securely. Users interact with the blockchain through a web interface that holds a MySQL database. In this paper, we present the system architecture, database schemas, operating sequence, sample code segments, and testing methods with an example of event ticket reselling. This system can create a secure, transparent, and trusted reselling service.