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, 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.
Robert Norvill, Beltrán Borja Fiz Pontiveros, Radu State, Andréa Cullen
In this work we present E-EVM, a tool that emulates and visualises the execution of smart contracts on the Ethereum Virtual Machine. By working with the readily available bytecode of smart contracts we are able to display the program's control flow graph, opcodes and stack for each step of contract execution. This tool is designed to aid the user's understanding of the Etheruem Virtual Machine as well as aid the analysis of any given smart contract. As such, it functions as both an analysis and a learning tool. It allows the user to view the code in each block of a smart contract and follow possible control flow branches. It is able to detect loops and suggest optimisation candidates. It is possible to step through a contract one opcode at a time. E-EVM achieved an average of 85.6% code coverage when tested.
Wazen M. Shbair, Mathis Steichen, Jérôme François, Radu State
Conducting experiments to evaluate blockchain applications is a challenging task for developers, because there is a range of configuration parameters that control blockchain environment. Many public testnets (e.g. Rinkeby Ethereum) can be used for testing, however, we cannot adjust their parameters (e.g. Gas limit, Mining difficulty) to further the understanding of the application in question and of the employed blockchain. This paper proposes an easy to use orchestration framework over the Grid'5000 platform. Grid'5000 is a highly reconfigurable and controllable large-scale testbed. We developed a tool that facilitates nodes reservation, deployment and blockchain configuration over the Grid'5000 platform. In addition, our tool can fine-tune blockchain and network parameters before and between experiments. The proposed framework offers insights for private and consortium blockchain developers to identify performance bottlenecks and to assess the behavior of their applications in different circumstances.
The Blockchain paradigm provides a popular mechanism for establishing trust and consensus in distributed environments. While Blockchain technology is currently primarily deployed in crypto-currency systems like Bitcoin, the concept is also expected to emerge as a key component of the Internet-of-Things (IoT), enabling novel applications in digital health, smart energy, asset tracking and smart transportation. As Blockchain networks evolve to industrial deployments with large numbers of geographically distributed nodes, the block transfer and processing delays arise as a critical issue which may create greater potential for forks and vulnerability to adversarial attacks. Motivated by these issues, we develop stochastic network models to capture the Blockchain evolution and dynamics and analyze the impact of the block dissemination delay and hashing power of the member nodes on Blockchain performance in terms of the overall block generation rate and required computational power for launching a successful attack. The results provide useful insight in crucial design issues, e.g., how to adjust the `difficulty-of-work' in the presence of delay so as to achieve a target block generation rate or appropriate level of immunity from adversarial attacks. We employ a combination of analytical calculations and simulation experiments to investigate both stationary and transient performance features, and demonstrate close agreement with measurements on a wide-area network testbed running the Ethereum protocol.
With the success of Bitcoin, the technique behind it, Blockchain, is catching massive attention recently. Blockchain is a collection of several techniques like cryptology, P2P and distributed consensus protocol. The main idea of Blockchain is that nodes in the network keep the same distributed ledger. Because of this immutable ledger, a trusted bridge is built among parties without fully trust. Blockchain can be used in variety of areas, especially in financial fields, like supply chain management, cross-border payment and global bank settlement. Meanwhile, we can observe that mobile network is growing rapidly and nibbling the PC market. However, the current public Blockchain applications like Bitcoin or Ethereum require the nodes to store the whole ledger which exceeds the capacity of the mobile devices. Thus, we need to develop a blockchain platform to support mobile devices. In this demo, we introduce Jupiter, a mobile-based Blockchain platform which provides a novel concept called consensus unit (CU) to alleviate the storage problem of mobile. We present the system architecture and demonstrate several CU scenarios via Jupiter.
Eung Seon Kang, Seung Jae Pee, Jae Song, Ju Wook Jang
The MicroGrid., as the need for renewable energy emerges, are becoming essential, renewable energy trading platforms are being developed and established in the microgrid. With the proliferation of technologies such as Smart home based of Internet of Things, interconnected networks, and Blockchain, microgrid has introduced a variety of applications and innovative solutions for efficient system maintenance. This paper, in a blockchain-based smart home, it is impossible to forge data called transaction generated by using blockchain. With this unforgeable transactions, home miner that centrally processes all the transactions generated in smart home know information about energy. Based on this information, we proposes renewable energy trading platform using ethereum's smart contract to ensure secure energy trading run automatically without the third party intervention in a microgrid.
Sina Rafati Niya, Florian Shupfer, Thomas Bocek, Burkhard Stiller
Smart Contracts (SC) extend the applicability of Blockchains (BC) in various decentralized use cases. This work demonstrates the design and implementation of a trading application which, employs SC and Ethereum BC. This Decentralized Application (Dapp) provides flexibility in requesting user Identity (ID) directly by seller/hirer and buyers/renter. To provide trust, deposits are paid by two sides while setting up contracts. WiFi- Direct is the chosen Device to Device (D2D) communication protocol which provides high data rates and secure data transmission. Light-Weight SC are introduced in this work which, use D2D communications for sending sold or rented object's or each party's images, and ID data directly to other party instead of storing them in the public BC to reduce the costs. Evaluations in terms of D2D deployment, transaction costs, and privacy, indicate that this system is time-efficient and manages the process in a cost-efficient fashion without the need to store and publish all of the user's ID information in BC.
Nida Khan, Abdelkader Lahmadi, Jérôme François, Radu State
Blockchain is an emerging foundational technology with the potential to create a novel economic and social system. The complexity of the technology poses many challenges and foremost amongst these are monitoring and management of blockchain-based decentralized applications. In this paper, we design, implement and evaluate a novel system to enable management operations in smart contracts. A key aspect of our system is that it facilitates the integration of these operations through dedicated 'managing' smart contracts to provide data filtering as per the role of the smart contract-based application user. We evaluate the overhead costs of such data filtering operations after post-deployment analyses of five categories of smart contracts on the Ethereum public testnet, Rinkeby. We also build a monitoring tool to display public blockchain data using a dashboard coupled with a notification mechanism of any changes in private data to the administrator of the monitored decentralized application.
Mohamed Tahar Hammi, Patrick Bellot, Ahmed Serhrouchni
Internet of Things becomes a major part of our lives, billions of autonomous devices are connected and communicate with each other. This revolutionary paradigm creates a new dimension that removes the boundaries between the real and the virtual worlds. The Wireless Sensor Networks are a masterpiece of the success of this technology, using limited capacity sensors and actuators, industrial, medical, agricultural and many other environments can be covered and managed automatically. This autonomous interacting things should authenticate each other, and communicate securely. Otherwise malicious users can cause serious damages on such systems. In this paper we propose a robust, transparent, flexible and energy efficient blockchain-based authentication mechanism called BCTrust, which is designed especially for devices with computational, storage and energy consumption constraints. In order to evaluate our approach, we realized a real implementation with C programming language, and Ethereum Blockchain.
Blockchain Technology Applications and Security
Cryptography and Data Security
Physical Unclonable Functions (PUFs) and Hardware Security
The blockchain technology witnessed a wide adoption and a swift growth in recent years. This ingenious distributed peer-to-peer design attracted several businesses and solicited several communities beyond the financial market. There are also multiple use cases built around its ecosystem. However, this backbone introduced a lot of speculation and has been criticized by several researchers. Moreover, the lack of legislations perceived a lot of attention. In this paper, we are concerned in analyzing blockchain networks and their development, focusing on their security challenges. We took a holistic approach to cover the involved mechanisms and the limitations of Bitcoin, Ethereum and Hyperledger networks. We expose also numerous possible attacks and assess some countermeasures to dissuade vulnerabilities on the network. For occasion, we simulated the majority and the re-entrancy attacks. The purpose of this paper is to evaluate Blockchain security summarizing its current state. Thoroughly showing threatening flaws, we are not concerned with favoring any particular blockchain network.
Sina Rafati Niya, Sanjiv S. Jha, Thomas Bocek, Burkhard Stiller
This work proposes an IoT- and Blockchain-based, distributed system, for automated measuring, storing, and monitoring of water and air quality in environments such as lakes, mountains, urban areas, or factories. Comparable state-of-the-art solutions, require human interaction to access the data or require high power consumption or space requirements, or they are based on centralized architectures. The proposed pollution monitoring system here, on one hand, employs LoRa to address the high power consumption and long-range transmission challenges of IoT protocols. On the other hand, it is designed to be fully decentralized by using the Ethereum Blockchain to store and retrieve the data recorded by IoT sensors. Thus, data integrity is provided without the need for a Trusted Third Party (TTP) and data is collected and captured automatically without any manual operations needed. Observations on the four different types of sensors for measuring Potential Hydrogen (PH), Turbidity, Carbon monoxide (CO), and Carbon dioxide (CO2), revealed a high accuracy with the expected time-lines of measurements, non-falsified experimental values collected and can be used as reliable evidence of presence of pollution.
Enabling search directly over encrypted data is a desirable technique to allow users to effectively utilize encrypted data outsourced to a remote server like cloud service provider. So far, most existing solutions focus on an honest-but-curious server, while security designs against a malicious server have not drawn enough attention. It is not until recently that a few works address the issue of verifiable designs that enable the data owner to verify the integrity of search results. Unfortunately, these verification mechanisms are highly dependent on the specific encrypted search index structures, and fail to support complex queries. There is a lack of a general verification mechanism that can be applied to all search schemes. Moreover, no effective countermeasures (e.g., punishing the cheater) are available when an unfaithful server is detected. In this work, we explore the potential of smart contract in Ethereum, an emerging blockchain-based decentralized technology that provides a new paradigm for trusted and transparent computing. By replacing the central server with a carefully-designed smart contract, we construct a decentralized privacy-preserving search scheme where the data owner can receive correct search results with assurance and without worrying about potential wrongdoings of a malicious server. To better support practical applications, we introduce fairness to our scheme by designing a new smart contract for a financially-fair search construction, in which every participant (especially in the multiuser setting) is treated equally and incentivized to conform to correct computations. In this way, an honest party can always gain what he deserves while a malicious one gets nothing. Finally, we implement a prototype of our construction and deploy it to a locally simulated network and an official Ethereum test network, respectively. The extensive experiments and evaluations demonstrate the practicability of our decentralized search scheme over encrypted data.
Because of the popularity of the Internet, the integration services have gradually changed people daily life, such as e-commerce activities on transactions, transportation and so on. The E-auction, one of the popular e-commerce activities, allows bidders to directly bid the products over the Internet. As for sealed bid, the extra transaction cost is required for the intermediaries because the third-party is the important role between the buyers and the sellers help to trade both during the auction. In addition, it never guarantees whether the third-party is trust. To resolve the problems, the blockchain technology with low transaction cost is used to develop the smart contract of public bid and sealed bid. The smart contract, proposed in 1990 and implements via Ethereum platform, can ensure the bill secure, private, non-reputability and inalterability owing to all the transactions are recorded in the same but decentralized ledgers. The smart contract is composed of the address of Auctioneer, the start auction time, deadline, the address of current winner, the current highest price. In the experiments, the accounts are created through Ethereum wallet. In miner stage, the MinerGate is used in miner stage for obtaining money to pay the transaction fee. At recorder stage, the nodes of blockchain are synchronized to generate smart contract.
An outdated Service Level Agreement (SLA) model, untrusted third parties with access to our data, unknown data location, and unwanted data movement continue to negatively affect trust in the cloud. The majority of current research into cloud trust focuses on ensuring a trustworthy hardware platform using attestations verified by some trusted third party(TTP). We are proposing an approach to improve cloud trust that leverages blockchain technology to help reduce the problem of depending on TTPs for policy evaluation and storage and help track our data. It provides consumers more control and expression of how they want their data handled and by whom. We propose to use Ethereum blockchain for storage and smart contracts as the vehicle for the policies. The main contributions presented in this research are: 1) storing policies in an authoritative source outside the cloud, 2) improving cloud trust by using decentralization, 3) providing a data movement policy model.
Many of today's crypto currencies use blockchains as decentralized ledgers and secure them with proof of work. In case of a fork of the chain, Bitcoin's rule for achieving consensus is selecting the longest chain and discarding the other chain as stale. It has been demonstrated that this consensus rule has a weakness against selfish mining in which the selfish miner exploits the variance in block generation by partially withholding blocks. In Ethereum, however, under certain conditions stale blocks don't have to be discarded but can be referenced from the main chain as uncle blocks yielding a partial reward. This concept limits the impact of network delays on the expected revenue for miners. But the concept also reduces the risk for a selfish miner to gain no rewards from withholding a freshly minted block. This paper uses a Monte Carlo simulation to quantify the effect of uncle blocks both to the profitability of selfish mining and the blockchain's security in Ethereum (ETH). A brief outlook about a recent Ethereum Classic (ETC) improvement proposal that weighs uncle blocks during the selection of the main chain will be given.
Being the largest blockchain with the capability of running smart contracts, Ethereum has attracted wide attention and its market capitalization has reached 20 billion USD. Ethereum not only supports its cryptocurrency named Ether but also provides a decentralized platform to execute smart contracts in the Ethereum virtual machine. Although Ether's price is approaching 200 USD and nearly 600K smart contracts have been deployed to Ethereum, little is known about the characteristics of its users, smart contracts, and the relationships among them. To fill in the gap, in this paper, we conduct the first systematic study on Ethereum by leveraging graph analysis to characterize three major activities on Ethereum, namely money transfer, smart contract creation, and smart contract invocation. We design a new approach to collect all transaction data, construct three graphs from the data to characterize major activities, and discover new observations and insights from these graphs. Moreover, we propose new approaches based on cross-graph analysis to address two security issues in Ethereum. The evaluation through real cases demonstrates the effectiveness of our new approaches.
In this paper, we propose IoTChain, a combination of the OSCAR architecture [1] and the ACE authorization framework [2] to provide an E2E solution for the secure authorized access to IoT resources. IoTChain consists of two components, an authorization blockchain based on the ACE framework and the OSCAR object security model, extended with a group key scheme. The blockchain provides a flexible and trustless way to handle authorization while OSCAR uses the public ledger to set up multicast groups for authorized clients. To evaluate the feasibility of our architecture, we have implemented the authorization blockchain on top of a private Ethereum network. We report on several experiments that assess the performance of different architecture components.
Blockchain is a highly popular paradigm for non-centralized applications, especially in finance and trade. Performance is a major challenge for blockchains, since consensus approaches are known not to scale. In this presentation we address blockchain performance, from the perspective of model-based prediction as well as benchmark-based assessment. We present research results about smart contracts in the Ethereum blockchain and discuss the requirements for generic benchmarks for blockchain performance. Benchmarking is a common approach to compare industry-class systems. As blockchain technologies mature, the role of reliable benchmarks will become increasingly important. However, definitions of benchmarks for blockchains are still in their infancy. We argue that there is a clear need for benchmarks, and that benchmarks should be based on the sound scientific principles of metrology [1]. A variety of important performance issues should be addressed, including the performance of the proof (be it work, stake, or other), transaction processing and block creation. Moreover, in all these situations, establishing energy consumption benchmarks is critical in determining if incentives are in place for miners to operate the blockchain system. A particularly interesting element in some blockchains is the mechanism of smart contracts. For instance, in Ethereum, the fees associated with executing contracts depend on the benchmarked performance of the operation code. In [2] it was demonstrated that uncertainty with respect to the correctness of the anticipated execution time impacts the decisions miners will take. We will discuss improved benchmarking approaches for operational code.
Introduction. Blockchain technology is becoming one of the main drivers of innovation in the global economy. Its adoption will have a huge impact on how businesses and governments operate and on the way people organize their everyday lives. Financial services industry is the one experiencing the biggest impact of the blockchain disruption so far, while financial institutions are among the first adopters of the technology. At the same time, being a relatively traditional industry, shipping has not yet seen many use cases with blockchain, but the technology is able to change this industry dramatically. Aim and tasks. As the industries of finance and shipping have huge potential in the blockchain space and often interact, determining how the blockchain technology adoption can influence the industries of finance and shipping in the future was the main purpose of this article. Research results. To fulfill this purpose, it was important to describe the origins of the blockchain technology, its main characteristics, functioning principles and consensus algorithms. Supported by the recent hype, cryptocurrencies are the biggest use case for blockchain so far, therefore, the article analyzes the largest of them, including Bitcoin, Ethereum and some others, as well as the cryptocurrency market as a whole. The level of worldwide adoption of blockchain and the overall market size are defined further in the article. Various applications in finance are also mentioned, paying particular attention to the insurance industry. Based on this information, the key areas in which blockchain can disrupt finance and insurance are identified. As the number of blockchain companies increases rapidly, the two main fundraising channels for such companies, venture capital and initial coin offering, are analyzed and compared. The ways in which blockchain may impact the shipping services industry are identified further. Conclusion. Afterwards, the article describes a number of blockchain consortia formed by public institutions and private entities to research and test possible applications of the technology across various industries and countries. While the potential of blockchain is still largely undiscovered, all the gathered information and performed research help to make a conclusion that the blockchain technology will have a big impact on many different industries, including financial and shipping services. The coming years will definitely see an exponentially growing interest in blockchain in academic and business fields, as the technology becomes more and more mainstream.
This article presents the formal syntax and semantics for a large subset of the Solidity programming language developed for the Etheruem blockchain platform based on our resent work about developing a general, extensible, and reusable formal memory (GERM) framework and an extension of Curry-Howard isomorphism, denoted as execution-verification isomorphism (EVI). This subset is denoted as Lolisa, which, to our knowledge, is the first mechanized and validated formal syntax and semantics developed for Solidity. The formal syntax of Lolisa adopts a stronger static type system than Solidity for enhanced type safety. In addition, Lolisa not only includes nearly all the syntax components of Solidity, such as mapping, modifier, contract, and address types, but it also contains general-purpose programming language features, such as multiple return values, pointer arithmetic, struct, and field access. Therefore, the inherent compatibility of Lolisa allows Solidity programs to be directly translated into Lolisa with a line-by-line correspondence without rebuilding or abstracting, and, in addition, the inherent generality of Lolisa allows it to be extended to express other programming languages as well. To this end, we also present a preliminary scheme for extending Lolisa to other languages systematically.
There is no doubt that Cryptocurrency is a word that provokes a very strong response these days. On one hand, Team Crypto proclaimers the arena as the next big thing as they speak in blue sky terms about the future of this new form of currency that takes digital shape and is beyond restriction. In direct opposition is Team Tradition that warns of the perils of decentralization and fraud around pure digital currency. Indeed, there was nothing short of a frenzy around trading on the CBOE Bitcoin futures a few days ago, while the day after reports detailed a large digital heist surrounding Ethereum. Doomsday sentiment around this new area of tech convergence with thaof the financial spectrum is plentiful. Just why is there so much fear around the area of cryptocurrency, and what will 2018 mean for this pioneering area, particularly as we move to a general cashless society that is easily driven and adopted by the massive Millennial demographic?
Blockchain technology has the potential to transform healthcare delivery by facilitating data sharing between providers and electronic health record (EHR) systems. However, significant roadblocks stand in the way of widespread implementation of this technology across the healthcare industry. Our blockchainbased data-sharing solution addresses two of the most critical challenges associated with using blockchain for health data sharing: protecting sensitive health information and deploying and installing blockchain software across diverse hospital environments. Since transparency is a fundamental feature of blockchain, we enabled user- and group-based secret sharing by adding purpose-built software that leverages a collection of well-established cryptographic algorithms. To streamline deployment, we built a containerized solution that guarantees portability, simplifies installation, and reduces overhead maintenance costs associated with administration. To ensure ease of implementation in a hospital system, we designed our blockchain solution using a distributed microservices architecture that allows us to encapsulate core functions of our system into isolated services that can be scaled independently based on the requirements of a particular hospital system deployment. As part of this architecture, we built core components for securely handling cryptographic secrets, interacting with blockchain nodes, facilitating large file sharing, enabling secondary-index based lookups, and integrating external business logic that governs how users interact with Smart Contracts. The innovative design of our blockchain solution, which addresses critical data security, deployment, and installation challenges, provides the healthcare community with a unique approach that has the power to connect providers while protecting sensitive data. Keywords: Blockchain, Data Sharing, Data Exchange, EHR,electronic health record, Ethereum, interplanetary file system, IPFS
Olivia Choudhury, Hillol Sarker, Nolan Rudolph, Morgan A. Foreman · 9 authors
Recent changes to the Common Rule, which govern Institutional Review Boards (IRB), require implementing new policies to strengthen research protocols involving human subjects. A major challenge in implementing such policies is an inability to automatically and consistently meet these ethical rules while securing sensitive information collected during the study. In this paper, we propose a novel framework, based on blockchain technology, to enforce IRB regulations on data collection. We demonstrate how to design smart contracts and a ledger to meet the requirements of an IRB protocol, including subject recruitment, informed consent management, secondary data sharing, monitoring risks, and generating automated assessments for continuous review. Furthermore, we show how we can employ the immutable transaction log in the blockchain to embed security in research activities by detecting malicious activities and robustly tracking subject involvement. We evaluate our approach by assessing its ability to enforce IRB guidelines in different types of human subjects studies, including a genomic study, a drug trial, and a wearable sensor monitoring study. Keywords: Blockchain, Data Sharing, Data Exchange, EHR, electronic health record, Ethereum, interplanetary filesystem, IPFS