Nota: Currently, the implementation of smart contracts is growing at impressive speeds, the \nnew blockchain technology and the proven accuracy of the data it offers means that more and \nmore private and public institutions adhere to this type of technology with the aim of take \nadvantage of all the benefits they offer. \nA specific problem that we face at the moment is the price variation in terms of the value of the \ncryptocurrencies used in the Smart Contracts, the so-called volatility, which directly affects the \nrate of adoption of the user who is accustomed to agree a value and receive the same agreed \nvalue, when cryptocurrencies are used to deploy intelligent contracts, the resulting values to \ncomply with them, is usually a different value from the agreed one. \nTo solve this problem, we propose the creation of a Token fixed to the anchored value of a \nstable currency, such as Dollar USD, Euro EUR, GBP Pound Sterling, etc., in this work a token \nwill be created with parity 1: 1 With the value of the dollar and how the network used for \ndevelopment is Ethereum, it has been named Ethereum-USA, USA, because it is the place \nwhere the American Dollar was originally used, and its symbol will be "E-USA”. \nThe Tokens have been created through intelligent contracts through Solidity and the TestNet \nRopsten test network has been used. \nThe present work presents a particular and novel tonic that justifies its creation, using the \nvarious cryptographic techniques that maintain the security of the network, the intelligent \ncontract that creates and uses the Tokens valued at $ 1 usd for the payment of services and \nsuppliers for the value of salaries quoted in Ecuador on the date of implementation. The same \nthat will be paid each end of the month. And for security and veracity, its support in the \nblockchain.
Micael Ferreira, Sven Rodrigues, Catarina I. Reis, Marisa Maximiano
Bitcoin continues to get more and more attention from the media, mainly because of the volatility of its value and insignificantly associated with the technological innovation. This cryptocurrency is supported by an immutable database and is distributed throughout a network of thousands of nodes, known as Blockchain. One way to ensure that all the concepts behind the Blockchain technology and infrastructure are seized is to conduct the development of one of the most popular context applications for it: a wallet for well-known cryptocurrencies. Yet Another Bitcoin Wallet (YABW) is a hybrid application available for both Android and iOS, which was developed with the Ionic and Angular frameworks. This application communicates with Bitcoin Blockchain to send, receive and store bitcoins; provides a set of features focused on security and user experience, and is available on the Play Store and Apple Store. A rather relevant issue that is becoming a major subject of current research is the application of the Blockchain infrastructure to other contexts that are neither directly connected to cryptocurrencies, nor are finance related. The implementation of a proof-of-concept application proposes the use of a blockchain for a specific case study: the exchange of meal vouchers of an institution amongst students. This is achieved using the decentralized platform Ethereum, which allows us to create a Smart Contract using the Solidity programming language to create a token that follows the Ethereum Request for Comment (ERC), the ERC-20 standard and represents the meal vouchers. This second application uses the architecture defined for YABW, reusing major components and custom developing specific modules to enhance the required features. There is still a lot of research to be done on the non-financial applicability of the Blockchain infrastructure and technology, but for the moment, we have left further evidence that it is possible and is a relative straight-forward process to accomplish from the technological perspective.
The rise of popular cryptocurrencies like Bitcoin and Ethereum has increased the popularity of blockchain technology, the framework these cryptocurrencies are built upon. The security and access control that blockchain technology has provided for cryptocurrencies has peaked the curiosity of other industries, realizing its potential value and future outlook. In this paper, we analyze two types of blockchains, permission-ed and permission-less, and introduce a two-tier blockchain concept utilizing both types for secure data sharing. We provide background on the consensus algorithms used for each blockchain type, Proof-of-Work and Proof-of-Authority. Testing on both Mac OS and Ubuntu Linux-based system environments, preliminary results show that by increasing the number of miners in a Proof-of-Work consensus, there is a correlating increase in the total block count in a permission-less blockchain, where the rate of increase is dependent on the system environment. In the Proof-of-Authority permission-ed blockchain, the block count observed little to no change across both environments.
Pilar Grau Carles, Diego Jaureguizar Arellano, Carlos Jaureguizar Francés
In this paper we examine the characteristics of the daily price series of 16 different cryptocurrencies between July 2017 and February 2018. The methodologies used for the analysis are the so-called Minimum Spanning Tree (MST) and hierarchical analysis by dendrogram, both obtained Pearson correlations between daily returns. This methodology visualizes the market relationships between the assets analyzed, identifying a high correlation between price movements for all the currencies. In addition, it has been possible to identify Ethereum’s position as a benchmark currency in the cryptocurrency market, rather than Bitcoin, as one might expect, due to its popularity and trading volume.
Block Chain (BC), the technology behind the Bitcoin crypto-currency system. Blockchain helps Build Trusted, Powerful and Transparent Process with the potential to disrupt Intermediaries, Third parties & Expensive processes. Proof-of-Work (PoW), Proof of Stake (PoS), Proof of Authority (PoA), consensus algorithm plays a vital role in ensuring BC security by maintaining a digital ledger of transactions, which is considered to be incorruptible. Firstly, we explore top crypto currencies after that we will explore blockchain and mining concept. In further we will be exploring Ethereum blockchain solidity programming more and make DAPPs on Ethereum blockchain network.
Blockchain is a decentralized technology. It has extensive power to solve business problems. Cryptography secures the records in a blockchain transaction and each transaction is tied to previous transactions or records. Blockchain transactions are validated by algorithms on the nodes. A single entity cannot create a transaction. Finally, blockchains provide transparency, giving each participant the ability to monitor the transactions at any time. Smart contract make secure transaction which helps to avoid third party disruption. Ethereum is a decentralized platform that runs smart contracts. This enables developers to create markets move funds in accordance with instructions given long in the past. The main features of blockchain are Decentralization, Immutability Faster dealings, Transaction and validation happens in seconds etc..
Smart contracts are a new paradigm that emerged with the rise of the blockchain technology. They allow untrusting parties to arrange agreements. These agreements are encoded as a programming language code and deployed on a blockchain platform, where all participants execute them and maintain their state. Smart contracts are promising since they are automated and decentralized, thus limiting the involvement of third trusted parties, and can contain monetary transfers. Due to these features, many people believe that smart contracts will revolutionize the way we think of distributed applications, information sharing, financial services, and infrastructures. To release the potential of smart contracts, it is necessary to connect the contracts with the outside world, such that they can understand and use information from other infrastructures. For instance, smart contracts would greatly benefit when they have access to web content. However, there are many challenges associated with realizing such a system, and despite the existence of many proposals, no solution is secure, provides easily-parsable data, introduces small overheads, and is easy to deploy. In this paper we propose PDFS, a practical system for data feeds that combines the advantages of the previous schemes and introduces new functionalities. PDFS extends content providers by including new features for data transparency and consistency validations. This combination provides multiple benefits like content which is easy to parse and efficient authenticity verification without breaking natural trust chains. PDFS keeps content providers auditable, mitigates their malicious activities (like data modification or censorship), and allows them to create a new business model. We show how PDFS is integrated with existing web services, report on a PDFS implementation and present results from conducted case studies and experiments.
Cryptocurrency is a well-developed blockchain technology application that is currently a heated topic throughout the world. The public availability of transaction histories offers an opportunity to analyze and compare different cryptocurrencies. In this paper, we present a dynamic network analysis of three representative blockchain-based cryptocurrencies: Bitcoin, Ethereum, and Namecoin. By analyzing the accumulated network growth, we find that, unlike most other networks, these cryptocurrency networks do not always densify over time, and they are changing all the time with relatively low node and edge repetition ratios. Therefore, we then construct separate networks on a monthly basis, trace the changes of typical network characteristics (including degree distribution, degree assortativity, clustering coefficient, and the largest connected component) over time, and compare the three. We find that the degree distribution of these monthly transaction networks cannot be well fitted by the famous power-law distribution, at the same time, different currency still has different network properties, e.g., both Bitcoin and Ethereum networks are heavy-tailed with disassortative mixing, however, only the former can be treated as a small world. These network properties reflect the evolutionary characteristics and competitive power of these three cryptocurrencies and provide a foundation for future research.
David M. Maslove, Jacob Klein, M. Kathryn Brohman, Patrick Martin
<sec> <title>BACKGROUND</title> Blockchain technology is emerging as an innovative tool in data and software security. </sec> <sec> <title>OBJECTIVE</title> This study aims to explore the role of blockchain in supporting clinical trials data management and develop a proof-of-concept implementation of a patient-facing and researcher-facing system. </sec> <sec> <title>METHODS</title> Blockchain-based Smart Contracts were built using the Ethereum platform. </sec> <sec> <title>RESULTS</title> We described BlockTrial, a system that uses a Web-based interface to allow users to run trials-related Smart Contracts on an Ethereum network. Functions allow patients to grant researchers access to their data and allow researchers to submit queries for data that are stored off chain. As a type of distributed ledger, the system generates a durable and transparent log of these and other transactions. BlockTrial could be used to increase the trustworthiness of data collected during clinical research with benefits to researchers, regulators, and drug companies alike. In addition, the system could empower patients to become more active and fully informed partners in research. </sec> <sec> <title>CONCLUSIONS</title> Blockchain technology presents an opportunity to address some of the common threats to the integrity of data collected in clinical trials and ensure that the analysis of these data comply with prespecified plans. Further technical work is needed to add additional functions. Policies must be developed to determine the optimal models for participation in the system by its various stakeholders. </sec>
Open access
Blockchain Technology Applications and Security
Ethics in Clinical Research
Artificial Intelligence in Healthcare and Education
This thesis focuses on aspects related to the functioning of the gossip\nnetworks underlying three relatively popular cryptocurrencies: Ethereum, Nano\nand IOTA.\n We look at topics such as automatic discovery of peers when a new node joins\nthe network, bandwidth usage of a node, message passing protocols and storage\nschemas and optimizations for the shared ledger. We believe this is a topic\nthat is often overlooked in works about blockchains and cryptocurrencies.\nVulnerabilities and inefficiencies attain a higher significance than ones in a\nregular open source project because of the rather direct financial implications\nof these projects. Barring Bitcoin, a network that has been around for nearly\n10 years, no other project has substantial documentation for its operational\ndetails other than scattered and sparse pages in the source code repositories.\nAlmost all of the content described here has been extracted by studying the\nsource code of the reference implementations of these projects.\n We evaluate the use of Invertible Bloom Lookup Tables and the Graphene\nprotocol to decrease block propagation times and bandwidth usage of certain\nmessages. We perform realistic simulations that show significant improvements.\nWe provide a complete implementation of Graphene in Geth, Ethereum's main node\nsoftware and test this implementation against the main Ethereum blockchain.\n We also crawled the chosen cryptocurrency networks for publicly visible nodes\nand provide an Autonomous System-level breakdown of these nodes with the end\ngoal of estimating the ease of performing attacks such as BGP hijacks and their\nimpact.\n Code written for implementing Graphene in Geth, performing various\nsimulations and for other miscellaneous tasks has been uploaded to Github at\nhttps://github.com/sunfinite/masters-thesis.\n
Envisioned 5G use cases arise challenges around the realization of inter-domain relationships beyond traditional Border Gateway Protocol (BGP) peering, e.g. end-to-end service deployments tailored to specific business needs (a.k.a. slices). Blockchain technologies bring consensus among decentralized non-trusting counterparts as a shared ledger, offering potential approaches for multi-administrative domain networking seeking agile, transparent end-to-end sliceable Service Level Agreements (SLAs). This demo showcases an experimental prototype based on best of breed open source components (e.g., Ethereum, OVS, Neo4j, Ryu/OpenFlowv1.3, ARIA/TOSCA) illustrating blockchain Decentralized Application (DApp) functionalities for life cycle management of multi-administrative domain network services.
Jialiang Chang, Bo Gao, Hao Xiao, Jun Sun · 6 authors
Ethereum smart contracts are an innovation built on top of the blockchain technology, which provides a platform for automatically executing contracts in an anonymous, distributed, and trusted way. The problem is magnified by the fact that smart contracts, unlike ordinary programs, cannot be patched easily once deployed. It is important for smart contracts to be checked against potential vulnerabilities. In this work, we propose an alternative approach to automatically identify critical program paths (with multiple function calls including inter-contract function calls) in a smart contract, rank the paths according to their criticalness, discard them if they are infeasible or otherwise present them with user friendly warnings for user inspection. We identify paths which involve monetary transaction as critical paths, and prioritize those which potentially violate important properties. For scalability, symbolic execution techniques are only applied to top ranked critical paths. Our approach has been implemented in a tool called sCompile, which has been applied to 36,099 smart contracts. The experiment results show that sCompile is efficient, i.e., 5 seconds on average for one smart contract. Furthermore, we show that many known vulnerabilities can be captured if user inspects as few as 10 program paths generated by sCompile. Lastly, sCompile discovered 224 unknown vulnerabilities with a false positive rate of 15.4% before user inspection.
Innerhalb der letzten Jahre wurden Blockchain-Technologien in vielen traditionellen Sektoren (z.B. im Finanzbereich) adaptiert. Dadurch wurden existierende Systeme neu überdacht und ganzheitlich neuartige Systeme erfunden. Allerdings blieb während dieser Zeit des raschen Fortschritts der Fokus stets auf der schnellen Produktentwicklung, was zu vielen Sicherheitsproblemen geführt hat durch die mehrere hundert Millionen von USD gestohlen oder verloren wurden. Nahezu alle derzeitig öffentlichen Blockchains bieten keine formale Semantik oder formales Framework zur Verifizierung von Smart-Contract-Code. Diese Arbeit präsentiert eine neuartige Semantik für Smart-Contract-Interaktionen und eine state-of-the-art Implementierung eines smart-contract-basierenden Investmentfonds für die Ethereum Blockchain. Der Fokus liegt darauf, eine formale Semantik für Smart Contracts mit dem tatsächlichen, wirtschaftlichen Anwendungsfall eines Investmentfonds zu verbinden. Genauer gesagt, die eingeführte Semantik bietet einen neuartigen Denkansatz dadurch, dass sie Smart Contract Interaktionen und nicht einzelne Smart-Contract-Ausführungen in den Mittelpunkt stellt. Die Blockchain wird durch einen Global State repräsentiert, auf welchem komplexe Transaktionen durch eine Big-Step-Semantik modelliert werden können. Der im Laufe dieser Arbeit entwickelte Investmentfonds ERCFund macht es möglich, in ein aktiv verwaltetes Portfolio von ERC20-Tokens und Ether zu investieren. Dies wird realisiert durch Tokens, welche als Anteil des Investmentfonds genutzt werden und je nach Bedarf gemünzt und vernichtet werden können. Außerdem unterstützt die Software mehrere fortgeschrittene Funktionen, wie z.B. Cold-Wallet-Support und Multi-Signature-Schutz durch Off-Chain-Signaturen. Wir zeigen, dass die eingeführte Semantik in einer realen, geschäftlichen Situation anwendbar ist, indem wir eine wesentliche Sicherheitsfunktion des Investmentfonds adaptieren und formal beweisen.
Jonathan Coignard, Eric Munsing, Jason MacDonald, Jonathan Mather
The increased penetration of Distributed Energy Resources (DERs) on the distribution network creates local challenges in balancing consumption and generation. To coordinate the roll-out and the operation of DERs, distribution-level energy markets have been proposed, but there are currently few tools for simulating the operation of DERs in these proposed markets. We present a framework which utilizes a grid co- simulation platform (Mosaik) to simulation DER operation, while simulating market clearing operations with a blockchain network (Ethereum). The use of blockchains, an emerging technology for decentralized computing and data storage, allows us to model secure decentralized execution of market clearing functions and payment processes. By unifying simulation of market clearing rules and the physical grid, we are able to ensure that economic incentives are aligned with physical constraints, helping facilitate the development of more effective distributed energy markets. We demonstrate the use of this new simulation platform on a small feeder, for which a market mechanism to incentivize DER integration is explored.
Νικόλαος Αλεξόπουλος, Sheikh Mahbub Habib, Max Mühlhäuser
Authorization, and more generally Trust Management (TM), is an indispensable part of the correct operation of most IT systems. The advent of the Internet of Things (IoT), with its cyber-physical and distributed nature, creates new challenges, that existing TM systems cannot adequately address, such as for example the need for non-interactive exclusive access enforcement. In the meantime, a line of thought in the research community is that Distributed Ledgers (DLs), like the one implemented by the Ethereum blockchain, can provide strong security guarantees for distributed access control. However, this approach has not yet been examined in a scientific, systematic manner, and has many pitfalls, with arguably the most important one being scalability.
Cryptocurrencies like Bitcoin not only provide a decentralized currency, but also provide a programmatic way to process transactions. Ethereum, the second largest cryptocurrency next to Bitcoin, is the first to provide a Turing-complete language to specify transaction processing, thereby enabling so-called smart contracts. This provides an opportune setting for attackers, as security vulnerabilities are tightly intertwined with financial gain. In this paper, we consider the problem of automatic vulnerability identification and exploit generation for smart contracts. We develop a generic definition of vulnerable contracts and use this to build TEE THER, a tool that allows creating an exploit for a contract given only its binary bytecode. We perform a large-scale analysis of all 38,757 unique Ethereum contracts, 815 out of which our tool finds working exploits for—completely automated.
Carlos Molina-Jiménez, Ioannis Sfyrakis, Ellis Solaiman, Irene C. L. Ng · 7 authors
Decentralised (on-blockchain) and centralised (off–blockchain) platforms are available for the implementation of smart contracts. However, none of the two alternatives can individually provide the services and quality of services (QoS) imposed on smart contracts involved in a large class of applications. The reason is that blockchain platforms suffer from scalability, performance, transaction costs and other limitations. Likewise, off–blockchain platforms are afflicted by drawbacks emerging from their dependence on single trusted third parties. We argue that in several applications, hybrid platforms composed from the integration of on and off–blockchain platforms are more adequate. Developers that informatively choose between the three alternatives are likely to implement smart contracts that deliver the expected QoS. Hybrid architectures are largely unexplored. To help cover the gap and as a proof of concept, in this paper we discuss the implementation of smart contracts on hybrid architectures. We show how a smart contract can be split and executed partially on an off–blockchain contract compliance checker and partially on the rinkeby ethereum network. To test the solution, we expose it to sequences of contractual operations generated mechanically by a contract validator tool.
We propose Parsec, a web-scale State channel for the Internet of Value to exterminate the consensus bottleneck in Blockchain by leveraging a network of state channels which enable to robustly transfer value off-chain. It acts as an infrastructure layer developed on top of Ethereum Blockchain, as a network protocol which allows coherent routing and interlocking channel transfers for trade-off between parties. A web-scale solution for state channels is implemented to enable a layer of value transfer to the internet. Existing network protocol on State Channels include Raiden for Ethereum and Lightning Network for Bitcoin. However, we intend to leverage existing web-scale technologies used by large Internet companies such as Uber, LinkedIn or Netflix. We use Apache Kafka to scale the global payment operation to trillions of operations per day enabling near-instant, low-fee, scalable, and privacy-sustainable payments. Our architecture follows Event Sourcing pattern which solves current issues of payment solutions such as scaling, transfer, interoperability, low-fees, micropayments and to name a few. To the best of knowledge, our proposed model achieve better performance than state-of-the-art lightning network on the Ethereum based (fork) cryptocoins.
In the era of the Internet of Things (IoT), smart connected devices have the ability to generate data that could be of interest to the public. This paves the way for an emerging market for monetized data exchanges, where IoT device owners can sell access to live data generated by their connected devices to interested users. Implementing a trusted, cost‐efficient, automatic monetization solution of IoT data can be a challenging problem and usually involves intermediaries and centralised governance and management. Blockchain and smart contracts introduce a secure and trusted platform to carry out transactions in a highly trusted, secure, decentralised manner. In this study, they present a blockchain‐solution and implementation using Ethereum smart contracts for monetizing IoT data with automated payment involving no intermediary. The authors discuss key aspects related to architectural design, entity relations, interactions among participants, logic flow, implementation and testing of the overall system functionality.
Stefano Angieri, Alberto García-Martínez, Bingyang Liu, Zhiwei Yan · 6 authors
The current system to manage the global pool of IP addresses is centralized\nin five transnational organizations, the Regional Internet Registries (RIRs).\nEach of these RIRs manage the address pool for a large number of countries.\nBecause the RIRs are private organizations, they are subject to the legal\nframework of the country where they are based. This configuration results in a\njurisdictional overflow from the legal framework of the countries where the RIR\nis based to all the countries that the RIRs are serving (the countries served\nby the RIRs de facto become subjects of the legal system of the country where\nthe RIR is hosted). The situation is aggravated by the deployment of new\nsecurity techniques such as the RPKI and BGPsec, that enable enforcement of\nallocations by the RIRs. In this paper we present InBlock, a blockchain-based\ndistributed governance body aimed to provide de-centralized management of IP\naddresses. InBlock also aims to fulfil the same objectives as the current IP\naddress allocation system, namely, uniqueness, fairness, conservation,\naggregation, registration and minimized overhead. InBlock is implemented as a\nDecentralized Autonomous Organization, i.e., as a set of blockchain's smart\ncontracts in Ethereum. Any entity may request an allocation of addresses to the\nInBlock registry by solely performing a (crypto)currency transfer to the\nInBlock. The fee required, along with the annual renewal fee, serves as a\nmechanism to deter stockpiling and other wasteful practices. As with any novel\ntechnology, there are many open questions about the usage of blockchains to\nbuild an IP address registry. For this reason, we believe that practical\nexperimentation is required in order to have hands-on experiences about such a\nsystem. We propose to conduct an experiment on distributed address management\nusing InBlock as a starting point to inform future directions in this area.\n
Introduction:. OPMEs have been singled out as items that increasingly compromise health care costs and are sometimes among the most expensive materials. Through supply chain management is known the cost containment, and because its unique features and because its homogeneous, decentralized and interconnected platform characteristics offered, Blockchain emerges as a natural solution for supply chain management. Objective: Develop a label based on the Blockchain Ethereum protocol for OPME. Methods: An antecedent search was performed in the databases: (LILACS, Medline, SciELO, Teses USP, Google and Google Scholar). For the development of the system, the methodology was used Design Thinking, which is divided into four phases: Discover, Define, Develop and Deliver. In the Discover phase, interviews were conducted and the Desk survey was produced; in the Define phase, the main functionalities of the system were determined; in the Developing phase, brainstorming sessions were held; and in the Deliver phase, the prototype and the final version of the service were produced. Results: From the Desk survey in the databases, articles for this research were found describing traceability services in supply chain management and articles reporting on Blockchain and Ethereum . No studies were found demonstrating its application. From the interviews and research Desk of the Discover phase, the functionalities and characteristics of the system were defined. The key is the need for an online service using Blockchain Ethereum technology to provide confidence to the relevant information in the OPME value chain. The prototype was developed and improved. The final system features all the functionality defined through Design Thinking Conclusion:. The label based on the Blockchain Ethereum protocol for OPME was designed.
One of the main issues in digital forensics is the management of evidences. From the time of evidence collection until the time of their exploitation in a legal court, evidences may be accessed by multiple parties involved in the investigation that take temporary their ownership. This process, called Chain of Custody (CoC), must ensure that evidences are not altered during the investigation, despite multiple entities owned them, in order to be admissible in a legal court. Currently digital evidences CoC is managed entirely manually with entities involved in the chain required to fill in documents accompanying the evidence. In this paper, we propose a Blockchain-based Chain of Custody (B-CoC) to dematerialize the CoC process guaranteeing auditable integrity of the collected evidences and traceability of owners. We developed a prototype of B-CoC based on Ethereum and we evaluated its performance.