Áron Lászka, Abhishek Dubey, Michael Walker, Douglas C. Schmidt
Power grids are undergoing major changes due to rapid growth in renewable energy resources and improvements in battery technology. While these changes enhance sustainability and efficiency, they also create significant management challenges as the complexity of power systems increases. To tackle these challenges, decentralized Internet-of-Things (IoT) solutions are emerging, which arrange local communities into transactive microgrids. Within a transactive microgrid, "prosumers" (i.e., consumers with energy generation and storage capabilities) can trade energy with each other, thereby smoothing the load on the main grid using local supply. It is hard, however, to provide security, safety, and privacy in a decentralized and transactive energy system. On the one hand, prosumers' personal information must be protected from their trade partners and the system operator. On the other hand, the system must be protected from careless or malicious trading, which could destabilize the entire grid. This paper describes Privacy-preserving Energy Transactions (PETra), which is a secure and safe solution for transactive microgrids that enables consumers to trade energy without sacrificing their privacy. PETra builds on distributed ledgers, such as blockchains, and provides anonymity for communication, bidding, and trading.
Transactive microgrids are emerging as a transformative solution for the\nproblems faced by distribution system operators due to an increase in the use\nof distributed energy resources and a rapid acceleration in renewable energy\ngeneration, such as wind and solar power. Distributed ledgers have recently\nfound widespread interest in this domain due to their ability to provide\ntransactional integrity across decentralized computing nodes. However, the\nexisting state of the art has not focused on the privacy preservation\nrequirement of these energy systems -- the transaction level data can provide\nmuch greater insights into a prosumer's behavior compared to smart meter data.\nThere are specific safety requirements in transactive microgrids to ensure the\nstability of the grid and to control the load. To fulfil these requirements,\nthe distribution system operator needs transaction information from the grid,\nwhich poses a further challenge to the privacy-goals. This problem is made\nworse by requirement for off-blockchain communication in these networks. In\nthis paper, we extend a recently developed trading workflow called PETra and\ndescribe our solution for communication and transactional anonymity.\n
Áron Lászka, Abhishek Dubey, Michael Walker, Douglas C. Schmidt
Power grids are undergoing major changes due to rapid growth in renewable\nenergy resources and improvements in battery technology. While these changes\nenhance sustainability and efficiency, they also create significant management\nchallenges as the complexity of power systems increases. To tackle these\nchallenges, decentralized Internet-of-Things (IoT) solutions are emerging,\nwhich arrange local communities into transactive microgrids. Within a\ntransactive microgrid, "prosumers" (i.e., consumers with energy generation and\nstorage capabilities) can trade energy with each other, thereby smoothing the\nload on the main grid using local supply. It is hard, however, to provide\nsecurity, safety, and privacy in a decentralized and transactive energy system.\nOn the one hand, prosumers' personal information must be protected from their\ntrade partners and the system operator. On the other hand, the system must be\nprotected from careless or malicious trading, which could destabilize the\nentire grid. This paper describes Privacy-preserving Energy Transactions\n(PETra), which is a secure and safe solution for transactive microgrids that\nenables consumers to trade energy without sacrificing their privacy. PETra\nbuilds on distributed ledgers, such as blockchains, and provides anonymity for\ncommunication, bidding, and trading.\n
Michael A. Walker, Abhishek Dubey, Áron Lászka, Douglas C. Schmidt
With the advent of blockchain-enabled IoT applications, there is an increased\nneed for related software patterns, middleware concepts, and testing practices\nto ensure adequate quality and productivity. IoT and blockchain each provide\ndifferent design goals, concepts, and practices that must be integrated,\nincluding the distributed actor model and fault tolerance from IoT and\ntransactive information integrity over untrustworthy sources from blockchain.\nBoth IoT and blockchain are emerging technologies and both lack codified\npatterns and practices for development of applications when combined. This\npaper describes PlaTIBART, which is a platform for transactive IoT blockchain\napplications with repeatable testing that combines the Actor pattern (which is\na commonly used model of computation in IoT) together with a custom Domain\nSpecific Language (DSL) and test network management tools. We show how\nPlaTIBART has been applied to develop, test, and analyze fault-tolerant IoT\nblockchain applications.\n
Transactive microgrids are emerging as a transformative solution for the problems faced by distribution system operators due to an increase in the use of distributed energy resources and a rapid acceleration in renewable energy generation, such as wind and solar power. Distributed ledgers have recently found widespread interest in this domain due to their ability to provide transactional integrity across decentralized computing nodes. However, the existing state of the art has not focused on the privacy preservation requirement of these energy systems -- the transaction level data can provide much greater insights into a prosumer's behavior compared to smart meter data. There are specific safety requirements in transactive microgrids to ensure the stability of the grid and to control the load. To fulfil these requirements, the distribution system operator needs transaction information from the grid, which poses a further challenge to the privacy-goals. This problem is made worse by requirement for off-blockchain communication in these networks. In this paper, we extend a recently developed trading workflow called PETra and describe our solution for communication and transactional anonymity.
The Bitcoin payment system involves two agent types: Users that transact with the currency and pay fees and miners in charge of authorizing transactions and securing the system in return for these fees. Two of Bitcoin's challenges are (i) securing sufficient miner revenues as block rewards decrease, and (ii) alleviating the throughput limitation due to a small maximal block size cap. These issues are strongly related as increasing the maximal block size may decrease revenue due to Bitcoin's pay-your-bid approach. To decouple them, we analyze the “monopolistic auction” [8], showing: (i) its revenue does not decrease as the maximal block size increases, (ii) it is resilient to an untrusted auctioneer (the miner), and (iii) simplicity for transaction issuers (bidders), as the average gain from strategic bid shading (relative to bidding one's true maximal willingness to pay) diminishes as the number of bids increases.
Blockchain systems are designed to produce blocks at a constant average rate. The most popular systems currently employ a Proof of Work (PoW) algorithm as a means of creating these blocks. Bitcoin produces, on average, one block every 10 minutes. An unfortunate limitation of all deployed PoW blockchain systems is that the time between blocks has high variance. For example, 5% of the time, Bitcoin's inter-block time is at least 40 minutes. This variance impedes the consistent flow of validated transactions through the system. We propose an alternative process for PoW-based block discovery that results in an inter-block time with significantly lower variance. Our algorithm, called Bobtail, generalizes the current algorithm by comparing the mean of the k lowest order statistics to a target. We show that the variance of inter-block times decreases as k increases. If our approach were applied to Bitcoin, about 80% of blocks would be found within 7 to 12 minutes, and nearly every block would be found within 5 to 18 minutes; the average inter-block time would remain at 10 minutes. Further, we show that low-variance mining significantly thwarts doublespend and selfish mining attacks. For Bitcoin and Ethereum currently (k=1), an attacker with 40% of the mining power will succeed with 30% probability when the merchant sets up an embargo of 8 blocks; however, when k>=20, the probability of success falls to less than 1%. Similarly, for Bitcoin and Ethereum currently, a selfish miner with 40% of the mining power will claim about 66% of blocks; however, when k>=5, the same miner will find that selfish mining is less successful than honest mining. The cost of our approach is a larger block header.
This letter revisits the informational efficiency of the Bitcoin market. In particular we analyze the time-varying behavior of long memory of returns on Bitcoin and volatility 2011 until 2017, using the Hurst exponent. Our results are twofold. First, R/S method is prone to detect long memory, whereas DFA method can discriminate more precisely variations in informational efficiency across time. Second, daily returns exhibit persistent behavior in the first half of the period under study, whereas its behavior is more informational efficient since 2014. Finally, price volatility, measured as the logarithmic difference between intraday high and low prices exhibits long memory during all the period. This reflects a different underlying dynamic process generating the prices and volatility.
Hyperledger Fabric (HLF) is a flexible permissioned blockchain platform designed for business applications beyond the basic digital coin addressed by Bitcoin and other existing networks. A key property of HLF is its extensibility, and in particular the support for multiple ordering services for building the blockchain. Nonetheless, the version 1.0 was launched in early 2017 without an implementation of a Byzantine fault-tolerant (BFT) ordering service. To overcome this limitation, we designed, implemented, and evaluated a BFT ordering service for HLF on top of the BFT-SMaRt state machine replication/consensus library, implementing also optimizations for wide-area deployment. Our results show that HLF with our ordering service can achieve up to ten thousand transactions per second and write a transaction irrevocably in the blockchain in half a second, even with peers spread in different continents.
The bitcoin peer-to-peer network has drawn significant attention from researchers, but so far has mostly focused on publicly visible portions of the network, i.e., publicly reachable peers. This mostly ignores the hidden parts of the network: unreachable Bitcoin peers behind NATs and firewalls. In this paper, we characterize Bitcoin peers that might be behind NATs or firewalls from different perspectives. Using a special-purpose measurement tool we conduct a large scale measurement study of the Bitcoin network, and discover several previously unreported usage patterns: a small number of peers are involved in the propagation of 89% of all bitcoin transactions, public cloud services are being used for Bitcoin network probing and crawling, a large amount of transactions are generated from only two mobile applications. We also empirically evaluate a method that uses timing information to re-identify the peer that created a transaction against unreachable peers. We find this method very accurate for peers that use the latest version of the Bitcoin Core client.
Stefanie Roos, Pedro Moreno-Sánchez, Aniket Kate, Ian Goldberg
Path-based transaction (PBT) networks, which settle payments from one user to\nanother via a path of intermediaries, are a growing area of research. They\novercome the scalability and privacy issues in cryptocurrencies like Bitcoin\nand Ethereum by replacing expensive and slow on-chain blockchain operations\nwith inexpensive and fast off-chain transfers. In the form of credit networks\nsuch as Ripple and Stellar, they also enable low-price real-time gross\nsettlements across different currencies. For example, SilentWhsipers is a\nrecently proposed fully distributed credit network relying on path-based\ntransactions for secure and in particular private payments without a public\nledger. At the core of a decentralized PBT network is a routing algorithm that\ndiscovers transaction paths between payer and payee. During the last year, a\nnumber of routing algorithms have been proposed. However, the existing ad hoc\nefforts lack either efficiency or privacy. In this work, we first identify\nseveral efficiency concerns in SilentWhsipers. Armed with this knowledge, we\ndesign and evaluate SpeedyMurmurs, a novel routing algorithm for decentralized\nPBT networks using efficient and flexible embedding-based path discovery and\non-demand efficient stabilization to handle the dynamics of a PBT network. Our\nsimulation study, based on real-world data from the currently deployed Ripple\ncredit network, indicates that SpeedyMurmurs reduces the overhead of\nstabilization by up to two orders of magnitude and the overhead of routing a\ntransaction by more than a factor of two. Furthermore, using SpeedyMurmurs\nmaintains at least the same success ratio as decentralized landmark routing,\nwhile providing lower delays. Finally, SpeedyMurmurs achieves key privacy goals\nfor routing in PBT networks.\n
New cryptocurrencies are emerging almost daily, and many interested parties are wondering whether central banks should issue their own versions. But what might central bank cryptocurrencies (CBCCs) look like and would they be useful? This feature provides a taxonomy of money that identifies two types of CBCC – retail and wholesale – and differentiates them from other forms of central bank money such as cash and reserves. It discusses the different characteristics of CBCCs and compares them with existing payment options.
As the core of intelligent manufacturing, cyber-physical systems (CPS) have serious security issues, especially for the communication security of their terminal machine-to-machine (M2M) communications. In this paper, blockchain technology is introduced to address such a security problem of communications between different types of machines in the CPS. According to the principles of blockchain technology, we designed a blockchain for secure M2M communications. As a communication system, M2M consists of public network areas, device areas, and private areas, and we designed a sophisticated blockchain structure between the public area and private area. For validating our design, we took cotton spinning production as a case study to demonstrate our solution to M2M communication problems under the CPS framework. We have demonstrated that the blockchain technology can effectively solve the safety of expansion of machines in the production process and the communication data between the machines cannot be tampered with.
Harry Kalodner, Steven Goldfeder, Alishah Chator, Malte Möser · 5 authors
Analysis of blockchain data is useful for both scientific research and commercial applications. We present BlockSci, an open-source software platform for blockchain analysis. BlockSci is versatile in its support for different blockchains and analysis tasks. It incorporates an in-memory, analytical (rather than transactional) database, making it several hundred times faster than existing tools. We describe BlockSci's design and present four analyses that illustrate its capabilities. This is a working paper that accompanies the first public release of BlockSci, available at https://github.com/citp/BlockSci. We seek input from the community to further develop the software and explore other potential applications.
Henrique Rocha, Sté́phane Ducasse, Marcus Denker, Jason Lecerf
Solidity is a language used to implement smart contracts on a blockchain platform. Since its initial conception in 2014, Solidity has evolved into one of the major languages for the Ethereum platform as well as other blockchain technologies. Due to its popularity, there are many tools specifically designed to handle smart contracts written in Solidity. However, there is a lack of tools for Pharo to handle Solidity contracts. Therefore, we implemented a parser using SmaCC to serve as a base for further developing Solidity support in Pharo. In this paper, we describe the parser creation, the irregularities we found in the Solidity grammar specification, and common practices on how to adapt the grammar to an LR type parser. Our experiences with parsing the Solidity language using SmaCC may help other developers trying to convert similar grammars.
Purpose With the rapid growth of the Internet of Things (IoT) market and requirement, low power wide area (LPWA) technologies have become popular. In various LPWA technologies, Narrow Band IoT (NB-IoT) and long range (LoRa) are two main leading competitive technologies. Compared with NB-IoT networks, which are mainly built and managed by mobile network operators, LoRa wide area networks (LoRaWAN) are mainly operated by private companies or organizations, which suggests two issues: trust of the private network operators and lack of network coverage. This study aims to propose a conceptual architecture design of a blockchain built-in solution for LoRaWAN network servers to solve these two issues for LoRaWAN IoT solution. Design/methodology/approach The study proposed modeling, model analysis and architecture design. Findings The proposed solution uses the blockchain technology to build an open, trusted, decentralized and tamper-proof system, which provides the indisputable mechanism to verify that the data of a transaction has existed at a specific time in the network. Originality/value To the best of our knowledge, this is the first work that integrates blockchain technology and LoRaWAN IoT technology.
Electric vehicles are gaining widespread adoption and are a key component in the establishment of the smart grid. Beside the increasing number of electric vehicles, a dense and widespread charging infrastructure will be required. This offers the opportunity for a broad range of different energy providers and charging station operators, both of which can offer energy at different prices depending on demand and supply. While customers benefit from a liberalized market and a wide selection of tariff options, such dynamic pricing use cases are subject to privacy issues and allow to detect the customer’s position and to track vehicles for, e.g., targeted advertisements. In this paper we present a reliable, automated and privacy-preserving selection of charging stations based on pricing and the distance to the electric vehicle. The protocol builds on a blockchain where electric vehicles signal their demand and charging stations send bids similar to an auction. The electric vehicle owner then decides on a particular charging station based on the supply-side offers it receives. This paper shows that the use of blockchains increases the reliability and the transparency of this approach while preserving the privacy of the electric vehicle owners.
Streszczenie: Celem zreferowanych w artykule bada jest ocena speniania przez kryptowalut funkcji ekonomicznych i spoecznych pienidza. W trakcie bada za pomoc programu komputerowego uzyskano 7561 Satoshi, ktre nastpnie poddano prbom uytkowym metod L
Technical, economic and social changes are happening so rapidly that it sometimes feels like a parallel universe operates alongside our own lives. The implications for investing are massive but unfathomable. Traditional financial analysis is spun on its head when the market values a company like Tesla higher than General Motors. In 2016, Tesla made a loss and produced only 76,000 cars, while GM had net income of US$9.4 billion and sold over 10 million vehicles. Uber churns through cash by the billion and will probably never make a profit, but is valued at US$70 billion. Have you ever heard of a game called Dungeon Fighter? Unbelievably, it has grossed more revenue since 2005 than Star Wars, Hollywood's leading franchise across eight movies, has earned since 1977.
Nabil Rifi, Elie Rachkidi, Nazim Agoulmine, Nada Chendeb Taher
In the past few years, the number of wireless devices connected to the Internet has increased to a number that could reach billions in the next few years. While cloud computing is being seen as the solution to process this data, security challenges could not be addressed solely with this technology. Security problems will continue to increase with such a model, especially for private and sensitive data such as data personal and medical data collected with more and more sophisticated connected devices (forming the IoT). Thus the need for a fully decentralized peer to peer and secure technology to overcome these problems. The blockchain Technology is a promising approach giving the properties it brings to the field. This paper illustrates an architecture based on blockchain technology, and a protocol for data access, using smart contracts and a publisher-subscriber mechanism.
Purwono Purwono, Alfian Ma’arif, Wahyu Rahmaniar, Qazi Mazhar ul Haq · 6 authors
Blockchain technology has a promising future in a number of industries and enterprises. Formerly connected to virtual currency like Bitcoin, blockchain has evolved into a versatile technology with many applications. In the upcoming years, it is predicted that blockchain will revolutionize a variety of industries, including banking, supply chain management, healthcare, voting systems, and more. The future of blockchain technology depends critically on its ability to increase security and transparency. By providing a decentralized and unchangeable record, eliminating the need for middlemen, and boosting participant confidence, blockchain promotes secure and traceable transactions. This transparency has the potential to transform whole industries by reducing fraud, streamlining processes, and increasing output. Blockchain also has the power to change financial systems. Blockchain-based smart contracts facilitate faster, more efficient transactions by automating and enforcing contractual agreements without the need for middlemen. By enabling speedier cross-border transactions, reducing costs, and boosting financial inclusion, tokenization and blockchain-based digital currencies have the potential to overturn conventional banking institutions. Blockchain’s key attributes, including decentralization, transparency, immutability, and security, make it a desirable choice for a range of organizations. Cross-border payments, trade finance, and smart contracts are just a few of the financial sector processes that blockchain technology has the potential to enhance and automate, lowering costs and increasing productivity. Additionally, the tamper-resistance of blockchain technology can boost transaction security and reliability, allowing for a wider use in traditional financial institutions. Outside of the financial industry, blockchain technology has a lot of promise, particularly in industries like supply chain management, healthcare, energy, intellectual property, and governance. By enabling transparent and traceable transactions, blockchain may improve supply chain efficiency, ensure product authenticity, and boost customer trust. By facilitating the secure exchange of patient data and research data, the decentralized nature of blockchain technology can enhance data security, interoperability, and privacy in the healthcare sector. A more decentralized and sustainable energy ecosystem may be supported by blockchain technology through peer-to-peer energy exchange, grid management, and monitoring of renewable energy certificates in the energy sector. Additionally, blockchain technology has the potential to transform decentralized governance structures, voting procedures, intellectual property rights, and digital identity management. By allowing people to own and manage their digital identities, blockchain can enhance privacy and reduce identity theft. Blockchain-based voting systems can offer transparency, security, and verifiability, thereby increasing voter turnout and public trust in democratic institutions. Blockchain can also enable the secure and transparent management of intellectual property rights, fostering author credit and just compensation.