Blockchain technology, which has been known by mostly small technological circles up until recently, is bursting throughout the globe, with a potential economic and social impact that could fundamentally alter traditional financial and social structures. Issuing cryptocurrencies on top of the Blockchain system by startups and private sector companies is becoming a ubiquitous phenomenon, inducing the trading of these crypto-coins among their holders using dedicated exchanges. Apart from being a trading ledger for tokens, Blockchain can also be observed as a social network. Analyzing and modeling the dynamics of the "social signals" of this network can contribute to our understanding of this ecosystem and the forces acting within in. This work is the first analysis of the network properties of the ERC20 protocol compliant crypto-coins' trading data. Considering all trading wallets as a network's nodes, and constructing its edges using buy--sell trades, we can analyze the network properties of the ERC20 network. Examining several periods of time, and several data aggregation variants, we demonstrate that the network displays strong power-law properties. These results coincide with current network theory expectations, however nonetheless, are the first scientific validation of it, for the ERC20 trading data. The data we examined is composed of over 30 million ERC20 tokens trades, performed by over 6.8 million unique wallets, lapsing over a two years period between February 2016 and February 2018.
Liam Bell, William J. Buchanan, Jonathan Cameron, Owen Lo
There are several areas of healthcare and well-being that could be enhanced using blockchain technologies. These include device tracking, clinical trials, pharmaceutical tracing, and health insurance. Within device tracking, hospitals can trace their asset within a blockchain infrastructure, including through the complete lifecycle of a device. The information gathered can then be used to improve patient safety and provide after-market analysis to improve efficiency savings. This paper outlines recent work within the areas of pharmaceutical traceability, data sharing, clinical trials, and device tracking. Keywords: Asset Tracking, Blockchain, Drug tracking, Ethereum, Healthcare, Internet of Things, IoT
Sergei Tikhomirov, Ekaterina Voskresenskaya, Ivan Ivanitskiy, Ramil Takhaviev · 6 authors
Ethereum is a major blockchain-based platform for smart contracts - Turing complete programs that are executed in a decentralized network and usually manipulate digital units of value. Solidity is the most mature high-level smart contract language. Ethereum is a hostile execution environment, where anonymous attackers exploit bugs for immediate financial gain. Developers have a very limited ability to patch deployed contracts. Hackers steal up to tens of millions of dollars from flawed contracts, a well-known example being "The DAO", broken in June 2016. Advice on secure Ethereum programming practices is spread out across blogs, papers, and tutorials. Many sources are outdated due to a rapid pace of development in this field. Automated vulnerability detection tools, which help detect potentially problematic language constructs, are still underdeveloped in this area.
Blockchain-based decentralized cryptocurrency platforms are currently one of the hottest topics in technology. Although most of the interest is generated by cryptocurrency related activities, it is becoming apparent that a much wider spectrum of applications can leverage the blockchain technology. The primary concepts enabling such general use of the blockchain are the so-called smart contracts, which are special programs that run on the blockchain. One of the most popular blockchain platforms that supports smart contracts is Ethereum. As smart contracts typically handle money, ensuring their low number of faults and vulnerabilities are essential. To aid smart contract developers and help to mature the technology, we need analysis tools and studies for smart contracts. As an initiative for this, we propose the adoption of some well-known OO metrics for Solidity smart contracts. Furthermore, we analyze more than 40 thousand Solidity source files with our prototype tool. The results suggest that smart contract programs are short, neither overly complex nor coupled too much, do not rely heavily on inheritance, and either quite well-commented or not commented at all. Moreover, smart contracts could benefit from an external library and dependency management mechanism, as more than 85% of the defined libraries in Solidity files code the same functionalities.
Santiago Bragagnolo, Henrique Rocha, Marcus Denker, Sté́phane Ducasse
Blockchains store a massive amount of heterogeneous data which will only grow in time. When searching for data on the Ethereum platform, one is required to either access the records (blocks) directly by using a unique identifier, or sequentially search several records to find the desired information. Therefore, we propose the Ethereum Query Language (EQL), a query language that allows users to retrieve information from the blockchain by writing SQL-like queries. The queries provide a rich syntax to specify data elements to search information scattered through several records. We claim that EQL makes it easier to search, acquire, format, and present information from the blockchain.
Grigory O. Krylov, A. Yu. Lisitsyn, Leonid I. Polyakov
The article provides a comparative analysis of the volatility of the leading national fiat currencies and their transnational anonymous analogues, which received the slang name “cryptocurrency”.Volatility is the most important financial indicator in the management of financial flows, as a measure of the risk of using a financial instrument at a specified period of time. Cryptocurrency mining technology is available to the general public and has become an innovative phenomenon. The latest fi phenomena need to be investigated, so it is necessary to conduct a multilateral scientific analysis, identification and comparison of cryptocurrency with fi currency. The aim of this study is to obtain new estimates of cryptocurrency based on the use of tools such as GARCH-model, simple historical volatility (SHV) and developed by the author’s toolkit, which is based on the Chaikin method. The methodological basis of the research is logical, econometric, economic and statistical methods of analysis, technical and fundamental analysis, and method of scientific visualization. The calculated volatility estimates are based on the Central Bank’s data on currency rates and investigated using named three models. The article for the first time presents the results of comparison of volatility of the leading fiat currencies (uS dollar, euro, Chinese yuan and Japanese yen) and the most popular today so-called cryptocurrencies (bicoin, litecoin, ethereum, and monero). Estimation of volatility showed that the volatility of bitcoin is significantly higher than fiat money. In this regard, it is concluded that the recognition of cryptocurrency, in particular bitcoin, as a real money is premature, not only due to the lack of regulations of a certain cryptocurrency as a legal tender, but also on the grounds of violation of essential requirements for the properties of the currency, such as a low level of volatility.
The efficiency of decentralized book systems like Bitcoin and Ethereum has always been a challenge. It is usually measured by three major factors: scalability, throughput, and latency. Scalability refers to how the system capacity is increased by adding more physical resources. Throughput measures the volume of transactions for a given period of time, where most current solutions attempt to improve such as NEO, EOS, etc. Latency measures the processing time of any single transaction. In current blockchain based systems, the block generation rate is the main latency bottleneck. Off-chain processes such as state channels are the most recent work that can integrate partial inbound transactions, reducing latency. Unfortunately, the state channel introduces more issues at the same time, such as cross-channel synchronization, which makes the state channel unavailable for full adoption of current blockchain solutions. In order to solve the efficiency problem, we proposed an end-to-end solution called ALZA, which links the dedicated high-throughput blockchain with self-organizing payment fields. This mechanism allows arbitrary set of users to create payment fields that process extremely low latency transactions within each field. Therefore, users can make transactions almost immediately. Since all transactions are conducted within fields, transaction costs will be reduced by several orders of magnitude. In addition, ALZA distributes main ledger to each client through an innovative replication mechanism. Therefore, the system will be significantly more robust to blockchain system failures. In theory, ALZA can complete millions of transactions in one second, which naturally supports high-frequency trading.
This paper describes the proof of concept of a blockchain based organization of a local low voltage energy community. The focus of the concept is efficient use of shared resources to minimize external dependence, and not energy trading. A previously proposed control algorithm, which exploits the power dependency of the efficiency of electrical energy storages, is implemented as a smart contract on a private instance of an Ethereum blockchain to coordinate the operation. It is implemented using four connected Raspberry Pis representing the participating households with pre-given electrical load and photovoltaic conversion as well as a battery. Each household runs an Ethereum full node and an interfacing software. Only the energy technology components are simulated, while the blockchain is actually running on the Raspberry Pis in order to mind the full complexity of the technology. The practicability is proved in a test run and positive effects on the efficiency and the self-sufficiency within the community are observed. A first cost-benefit estimate is given and a further research agenda is presented.
Starting with BitTorrent and then Bitcoin, decentralized technologies have been on the rise over the last 15+ years, gaining significant momentum in the last 2+ years with the advent of platform ecosystems such as the Blockchain platform Ethereum. New projects have evolved from decentralized games to marketplaces to open funding models to decentralized autonomous organizations. The hype around cryptocurrency and the valuation of innovative projects drove the market cap of cryptocurrencies to over a trillion dollars at one point in 2017. These high valued technologies are now enabling something new: globally scaled and decentralized business models. Despite their valuation and the hype, these new business ecosystems are frail. This is not only because the underlying technology is rapidly evolving, but also because competitive markets see a profit opportunity in exponential cryptocurrency returns. This extracts value from these ecosystems, which could lead to their collapse, if unchecked. In this paper, we explore novel ways for decentralized economies to protect themselves from, and coexist with, competitive markets at a global scale utilizing decentralized technologies such as Blockchain.
Yandamuri, Sravya, Abraham, Ittai, Nayak, Kartik, Reiter, Michael K.
A smart contract on a blockchain cannot keep a secret because its data is replicated on all nodes in a network. To remedy this problem, it has been suggested to combine blockchains with trusted execution environments (TEEs), such as Intel SGX, for executing applications that demand privacy. Untrusted blockchain nodes cannot get access to the data and computations inside the TEE. This paper first explores some pitfalls that arise from the combination of TEEs with blockchains. Since TEEs are, in principle, stateless they are susceptible to rollback attacks, which should be prevented to maintain privacy for the application. However, in blockchains with non-final consensus protocols, such as the proof-of-work in Ethereum and others, the contract execution must handle rollbacks by design. This implies that TEEs for securing blockchain execution cannot be directly used for such blockchains; this approach works only when the consensus decisions are final. Second, this work introduces an architecture and a prototype for smart-contract execution within Intel SGX technology for Hyperledger Fabric, a prominent platform for enterprise blockchain applications. Our system resolves difficulties posed by the execute-order-validate architecture of Fabric and prevents rollback attacks on TEE-based execution as far as possible. For increasing security, our design encapsulates each application on the blockchain within its own enclave that shields it from the host system. An evaluation shows that the overhead moving execution into SGX is within 10%-20% for a sealed-bid auction application.
Yackolley Amoussou-Guenou, Antonella Del Pozzo, Maria Potop-Butucaru, Sara Tucci-Piergiovanni
Tendermint-core blockchains (e.g. Cosmos) are considered today one of the most viable alternatives for the highly energy consuming proof-of-work blockchains such as Bitcoin and Ethereum. Their particularity is that they aim at offering strong consistency (no forks) in an open system combining two ingredients (i) a set of validators that generate blocks via a variant of Practical Byzantine Fault Tolerant (PBFT) consensus protocol and (ii) a selection strategy that dynamically selects nodes to be validators for the next block via a proof-of-stake mechanism. However,the exact assumptions on the system model under which Tendermint underlying algorithms are correct and the exact properties Tendermint verifies have never been formally analyzed. The contribution of this paper is two-fold. First, while formalizing Tendermint algorithms we precisely characterize the system model and the exact problem solved by Tendermint. We prove that in eventual synchronous systems a modified version of Tendermint solves (i) under additional assumptions, a variant of one-shot consensus for the validation of one single block and (ii) a variant of the repeated consensus problem for multiple blocks. These results hold even if the set of validators is hit by Byzantine failures, provided that for each one-shot consensus instance less than one third of the validators is Byzantine. Our second contribution relates to the fairness of the rewarding mechanism. It is common knowledge that in permisionless blockchain systems the main threat is the tragedy of commons that may yield the system to collapse if the rewarding mechanism is not adequate. Ad minimum the rewarding mechanism must be fair, i.e.distributing the rewards in proportion to the merit of participants. We prove, for the first time in blockchain systems, that in repeated-consensus based blockchains there exists an (eventual) fair rewarding mechanism if and only if the system is (eventual) synchronous. We also show that the original Tendermint rewarding is not fair, however, a modification of the original protocol makes it eventually fair.
This article presents a new method for managing digital reuse rights of research data, which leverages technologies such as the blockchain and smart contracts. This allows, on one hand, the creation of a permanent record on the agreements between the authors of the data and the reusers, with the possibility of verifying compliance at any time, and on the other hand, a higher level of granularity on defining the conditions of reuse. A practical implementation of such a workflow using the Solidity smart contract language is included, along with a brief analysis over the Ethereum blockchain network.
Freya Sheer Hardwick, Raja Naeem Akram, Konstantinos Markantonakis
At a time when society is in constant transition to keep up with technological advancement, we are seeing traditional paradigms being increasingly challenged. The fundamentals of governance are one such paradigm. As society's values have shifted, so have expectations of government shifted from the traditional model to something commonly referred to as `open governance'. Though a disputed term, we take open governance to mean a concept, which encourages and facilitates openness, accountability, and responsiveness to citizens. For the success of open governance initiatives, there are some technologies, such as the internet, that are crucial. These technologies enable access to both the data and to engagement activities between citizens and government. There are also other technologies, like blockchain and smart contacts, which could be utilised to assist open governance. A sound starting point would be moving from a system where information is tediously released by a government, on an `as they please' basis, to an infrastructure where critical actions are captured with strong integrity, non-repudiation and evidential guarantees. With an added dimension that facilitates these actions record be accessible to public scrutiny in near real-time. One candidate technology for capturing such actions is blockchain. Initially, blockchains were mainly used to facilitate cryptocurrencies as a record of transactions. The notable example being bitcoin. However, in recent years, blockchains utility is being recognised through smart contracts - potentially a vital building block to realising open and transparent government activities. In this paper, we employ the concept of smart contracts to government tendering activities. The proposed scheme is based on smart contracts, enabling a fair, transparent and independently verifiable (auditable) government tendering scheme. The scheme is then implemented on the Ethereum platform to evaluate the performance and financial cost implications, along with an evaluation of the potential security and auditability challenges.
Parinya Ekparinya, Vincent Gramoli, Guillaume Jourjon
Recently, several works conjectured the vulnerabilities of mainstream blockchains under several network attacks. All these attacks translate into showing that the assumptions of these blockchains can be violated in theory or under simulation at best. Unfortunately, previous results typically omit both the nature of the network under which the blockchain code runs and whether blockchains are private, consortium or public. In this paper, we study the public Ethereum blockchain as well as a consortium and private blockchains and quantify the feasibility of man-in-the-middle and double spending attacks against them. To this end, we list important properties of the Ethereum public blockchain topology, we deploy VMs with constrained CPU quantum to mimic the top-10 mining pools of Ethereum and we develop full-fledged attacks, that first partition the network through BGP hijacking or ARP spoofing before issuing a Balance Attack to steal coins. Our results demonstrate that attacking Ethereum is remarkably devastating in a consortium or private context as the adversary can multiply her digital assets by 200, 000x in 10 hours through BGP hijacking whereas it would be almost impossible in a public context.
OpenLitterMap rewards users with Littercoin for producing open data on litter. Open data on the geospatial characteristics of litter provide means of invoking and evaluating responses to plastic pollution. OpenLitterMap currently works as a web app on all devices with native mobile apps in development. The stack includes the integration of the Laravel PHP Framework on the backend; Vue for frontend reactivity; NativeScript-Vue for mobile apps; Bulma for CSS; Leaflet for web-mapping; Turf.js for geospatial analysis; the Ethereum Blockchain for tokenization; Stripe; ChartJS; AWS; and more. Anywhere from a single cigarette butt to the contents of an entire beach or street clean can be logged in a single geotagged photo. Alternatively, a simple index may be used if litter is incalculable. The open data includes an increasing 100+ pre-defined types of litter; 20+ corporate brands; verification status; coordinates; timestamp; phone model; the latest OpenStreetMap address at each location; and the litter presence as a Boolean. To date, 100% of all submitted data (~ 8200 photos, ~ 28,000 litter from over 150 contributors) has been manually verified which is being used to develop machine learning algorithms.
Die Autoren gehen der Frage nach, ob Kryptowährungen als Sachen im Sinne des ZGB aufgefasst und daran namentlich Eigentumsrechte begründet werden können. Dabei werden zunächst technische Grundlagen der sog. Blockchain-Technologie und der drei nach Markkapitalisierung grössten Kryptowährungen Bitcoin (BTC), Ethereum (Ether, ETH) und Ripple (XRP) dargestellt. Sodann wird untersucht, ob diese Kryptowährungen die Eigenschaften erfüllen, welche für die Qualifikation eines Objektes als Sache im Sinne des ZGB vorliegen müssen, und welches die Folgen einer solchen Qualifikation sind. Im Sinne einer modernen Auslegung des Sachbegriffs schliessen sich die Autoren der Auffassung an, wonach Kryptowährungen grundsätzlich als Sache und damit als Gegenstand des Eigentums zu behandeln sind.
Eric Zhang, C Hendrik, Yang Liu, Archit Sharma · 5 authors
In this paper we present the initial design of Minerva consensus protocol for Truechain and other technical details. Currently, it is widely believed in the blockchain community that a public chain cannot simultaneously achieve high performance, decentralization and security. This is true in the case of a Nakamoto chain (low performance) or a delegated proof of stake chain (partially centralized), which are the most popular block chain solutions at time of writing. Our consensus design enjoys the same consistency, liveness, transaction finality and security guarantee, a de-facto with the Hybrid Consensus. We go on to propose the idea of a new virtual machine on top of Ethereum which adds permissioned-chain based transaction processing capabilities in a permissionless setting. We also use the idea of data sharding and speculative transactions, and evaluation of smart contracts in a sharding friendly virtual machine. Finally, we will briefly discuss our fundamentally ASIC resistant mining algorithm, Truehash.
Maxim Ya. Afanasev, Anastasiya A. Krylova, Sergey A. Shorokhov, Yuri V. Fedosov · 5 authors
The concept of cyber-physical production systems is highly discussed amongst researchers and industry experts, however, the implementation options for these systems rely mainly on obsolete technologies. Despite the fact that the blockchain is most often associated with cryptocurrency, it is fundamentally wrong to deny the universality of this technology and the prospects for its application in other industries. For example, in the insurance sector or in a number of identity verification services. This article discusses the deployment of the CPPS backbone network based on the Ethereum private blockchain system. The structure of the network is described as well as its interaction with the help of smart contracts, based on the consumption of cryptocurrency for various operations.
Motivated by the great success and adoption of Bitcoin, a number of cryptocurrencies such as Litecoin, Dogecoin, and Ethereum are becoming increasingly popular. Although existing blockchain-based cryptocurrency schemes can ensure reasonable security for transactions, they do not consider any notion of fairness. Fair exchange allows two players to exchange digital “items,” such as digital signatures, over insecure networks fairly, so that either each player gets the other's item, or neither player does. Given that blockchain participants typically do not trust each other, enabling fairness in existing cryptocurrencies is an essential but insufficiently explored problem. In this article, we explore the solution space for enabling the fair exchange of a cryptocurrency payment for a receipt. We identify the timeliness of an exchange as an important property especially when one of the parties involved in the exchange is resource-constrained. We introduce the notion of strong timeliness for a fair exchange protocol and propose two fair payment-for-receipt protocol instantiations that leverage functionality of the blockchain to achieve strong timeliness. We implement both and compare their security and efficiency.
Tourism destinations are always seeking new and innovative ways to better market tourism offerings and increase tourism revenues. This paper seeks to highlight a future tourism marketing trend through the use of virtual environments (VE) backed by Distributed Ledger Technologies (DLT’s) such as Blockchain. VE is the umbrella term referring to virtual reality (VR), augmented reality (AR) and mixed reality (MR), also known as merged reality. The virtual reality market is said to be the next frontier in digital marketing and in recent years the tourism industry has slowly taken advantage of developments in the virtual space. On the other hand, DLT’s such as Blockchain technology is bound to revolutionize and disrupt various business sectors such as the financial and supply chain management sectors, among many. An indicator of this is the number of Fortune 500 companies that are members of the Enterprise Ethereum Alliance – an alliance that is seeking to build enterprise-grade software on the Ethereum Blockchain. The analysis suggest that VR based tourism utilizing DLT’s can positively impact the tourism industry and provide a means for additional revenue.
The use of technology has become important at this point in helping to meet human needs.Due to the increasing use of technology, new challenges are brought in the process of democracy as most people today don’t trust their governments, making elections is very important in modern democracy . Elections have a great importance in determining who will rule a nation or an organization or it can be said as it is an event that decides the fate of any nation. In modern democracy, elections are very important but large sections of society around the world do not trust their election system which is a major concern for democracy. Even the world’s largest democracies like India, United States, still suffer from a flawed electoral system. Vote rigging, hacking of EVM (Electronic voting machine), election manipulation, and polling booth capturing are the major issues in the current voting system The blockchain is said as emerging, decentralized, and distributed technology that promises to enhance different aspects of many industries. Expanding e-voting into blockchain technology could be the solution to eliminate the present concerns in e-voting system There is no doubt that the ever changing concept of the blockchain, which is the backbone of the famous cryptocurrency Bitcoin has triggered the start of a new era in the Internet and the online services. While most people focus only on bitcoin and other cryptocurrencies; there are in fact, many operations, both administrative and fintech that can only be done online/offline can now safely be moved to the Internet as online services because of immutability of blockchain. What makes blockchain a powerful tool is its smarts contracts and many features which overcomes traditional systems. Smart contracts are meaningful pieces of codes, to be integrated in the blockchain and executed as scheduled in every step of blockchain updates. E-votin, is another trending, yet critical, topic related to the online services. The blockchain with the smart contracts, emerges as a good candidate to use in developments of safer, cheaper, more secure, more transparent, and easier-to-use e-voting systems.Due to its consistency, widespread use, and provision of smart contracts logic, Ethereum and its network is one of the most suitable ones. An e-voting system must be secure, as it should not allow duplicated votes and be fully transparent, while protecting the privacy of the attendees. In this project, we have implemented and tested an e-voting application as a smart contract for the Ethereum network using the Ethereum and the Solidity language.
Miguel Pincheira, Muhammad Salek Ali, Massimo Vecchio, Raffaele Giaffreda
The recent, exponential rise in adoption of the most disparate Internet of Things (IoT) devices and technologies has reached also Agriculture and Food (Agri-Food) supply chains, drumming up substantial research and innovation interest towards developing reliable, auditable and transparent traceability systems. Current IoT-based traceability and provenance systems for Agri-Food supply chains are built on top of centralized infrastructures and this leaves room for unsolved issues and major concerns, including data integrity, tampering and single points of failure. Blockchains, the distributed ledger technology underpinning cryptocurrencies such as Bitcoin, represent a new and innovative technological approach to realizing decentralized trustless systems. Indeed, the inherent properties of this digital technology provide fault-tolerance, immutability, transparency and full traceability of the stored transaction records, as well as coherent digital representations of physical assets and autonomous transaction executions. This paper presents AgriBlockIoT, a fully decentralized, blockchain-based traceability solution for Agri-Food supply chain management, able to seamless integrate IoT devices producing and consuming digital data along the chain. To effectively assess AgriBlockIoT, first, we defined a classical use-case within the given vertical domain, namely from-farm-to-fork. Then, we developed and deployed such use-case, achieving traceability using two different blockchain implementations, namely Ethereum and Hyperledger Sawtooth. Finally, we evaluated and compared the performance of both the deployments, in terms of latency, CPU, and network usage, also highlighting their main pros and cons.
With the tremendous development of internet, we can share any media from anywhere in the world. This paved the way for data sharing illegally versions of data shared among persons. In our proposed system, the original data (use case taken Song) will be embedded with a hash value and then deployed to Inter Planetary File System (IPFS) and shared through Ethereum Blockchain, enabling deployed data unaltered. The IPFS returns a 46-bit length hash for each of the file being upload. Usage of Ethereum blockchain ensures each every transaction cryptographically hashed and logged. Also, the data deployed on IPFS sharable but with hidden hash identity for each of it, which is not known by the person who gets that data. The owner of the original data thus shares the data and w having the log maintaining hash identity for each of the person to whom the data owner shares. The IPFS storage enables Peer to Peer (P2P) data transfer through decentralized network. The person will be given the IPFS hash to download the data. When data if pirated is known to the owner, he computes the hash value from the pirated version and identifies the person pirated that data and avoids sharing data to that person next time
Nowadays, blockchain is becoming a synonym for distributed ledger technology. However, blockchain is only one of the specializations in the field and is currently well-covered in existing literature, but mostly from a cryptographic point of view. Besides blockchain technology, a new paradigm is gaining momentum: directed acyclic graphs. The contribution presented in this paper is twofold. Firstly, the paper analyzes distributed ledger technology with an emphasis on the features relevant to distributed systems. Secondly, the paper analyses the usage of directed acyclic graph paradigm in the context of distributed ledgers, and compares it with the blockchain-based solutions. The two paradigms are compared using representative implementations: Bitcoin, Ethereum and Nano. We examine representative solutions in terms of the applied data structures for maintaining the ledger, consensus mechanisms, transaction confirmation confidence, ledger size, and scalability.