Blockchains and Smart Contracts for the Internet of Things
TL;DR: The conclusion is that the blockchain-IoT combination is powerful and can cause significant transformations across several industries, paving the way for new business models and novel, distributed applications.
Abstract: Motivated by the recent explosion of interest around blockchains, we examine whether they make a good fit for the Internet of Things (IoT) sector. Blockchains allow us to have a distributed peer-to-peer network where non-trusting members can interact with each other without a trusted intermediary, in a verifiable manner. We review how this mechanism works and also look into smart contracts—scripts that reside on the blockchain that allow for the automation of multi-step processes. We then move into the IoT domain, and describe how a blockchain-IoT combination: 1) facilitates the sharing of services and resources leading to the creation of a marketplace of services between devices and 2) allows us to automate in a cryptographically verifiable manner several existing, time-consuming workflows. We also point out certain issues that should be considered before the deployment of a blockchain network in an IoT setting: from transactional privacy to the expected value of the digitized assets traded on the network. Wherever applicable, we identify solutions and workarounds. Our conclusion is that the blockchain-IoT combination is powerful and can cause significant transformations across several industries, paving the way for new business models and novel, distributed applications.
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TL;DR: This article provides an overview of the key features of peer-to-peer trading and its benefits of relevance to the grid and prosumers, and systematically classify the existing research in terms of the challenges that the studies address in the virtual and the physical layers.
Abstract: Peer-to-peer trading is a next-generation energy management technique that economically benefits proactive consumers (prosumers) transacting their energy as goods and services. At the same time, peer-to-peer energy trading is also expected to help the grid by reducing peak demand, lowering reserve requirements, and curtailing network loss. However, large-scale deployment of peer-to-peer trading in electricity networks poses a number of challenges in modeling transactions in both the virtual and physical layers of the network. As such, this article provides a comprehensive review of the state-of-the-art in research on peer-to-peer energy trading techniques. By doing so, we provide an overview of the key features of peer-to-peer trading and its benefits of relevance to the grid and prosumers. Then, we systematically classify the existing research in terms of the challenges that the studies address in the virtual and the physical layers. We then further identify and discuss those technical approaches that have been extensively used to address the challenges in peer-to-peer transactions. Finally, the paper is concluded with potential future research directions.
443 citations
Cites background from "Blockchains and Smart Contracts for..."
...for trusted intermediaries between transacting parties, and the occurance of malicious and accidental exceptions can be minimized [95]....
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...same functionality with the same amount of certainty [95]....
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TL;DR: A systematic review of the literature finds four main clusters in the co-citation analysis, namely Technology, Trust, Trade, and Traceability/Transparency, and discusses the emerging themes and applications of blockchains for supply chains, logistics and transport.
Abstract: This paper presents current academic and industrial frontiers on blockchain application in supply chain, logistics and transport management. We conduct a systematic review of the literature and find four main clusters in the co-citation analysis, namely Technology, Trust, Trade, and Traceability/Transparency. For each cluster, and based on the pool of articles included in it, we apply an inductive method of reasoning and discuss the emerging themes and applications of blockchains for supply chains, logistics and transport. We conclude by discussing the main themes for future research on blockchain technology and its application in industry and services.
437 citations
Cites background from "Blockchains and Smart Contracts for..."
...One of the most important aspects of blockchain application is their interface with the physical world, which requires the right tools and technology such as IoT (Christidis and Devetsikiotis 2016; Catallini 2017)....
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...Moreover, as can be seen in Table 1, there can be overlaps between the clusters where the same article has been included in two or more clusters (e.g. Christidis and Devetsikiotis (2016) is included in both clusters 1 and 2)....
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...Blockchain technology has so far been envisaged to be implemented in machine-to-machine coordination through IoT (e.g. Christidis and Devetsikiotis 2016) or to create decentralised electronic marketplaces (e.g. Subramanian 2018), to name a few applications....
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...…2015; Rong et al. 2015; Ben-Daya, Hassini, and Bahroun 2017), the high costs of maintaining centralised IoT systems in supply chains (Christidis and Devetsikiotis 2016) and the security concerns surrounding IoT devices such as RFID-enabled products (Yao et al. 2016) that could easily breach the…...
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...Christidis and Devetsikiotis (2016) provide further details on how users of blockchains interact and reach consensus....
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TL;DR: A comprehensive top down survey of the most recent proposed security and privacy solutions in IoT in terms of flexibility and scalability and a general classification of existing solutions is given.
432 citations
Cites background from "Blockchains and Smart Contracts for..."
...We mean by smart contracts, all kinds of digital rules forming the terms of contact [31]....
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TL;DR: It is argued that blockchain's decentralized feature is likely to result in a low susceptibility to manipulation and forgery by malicious participants, and public policy efforts directed at protecting privacy using blockchain should focus on providing training to key stakeholders and increasing investment in this technology.
430 citations
Cites background from "Blockchains and Smart Contracts for..."
...Prior researchers have noted that especially the blockchain-IoT combination is likely to be powerful and this combination will probably transform many industries (Christidis & Devetsikiotis, 2016)....
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TL;DR: In this article, a systematic review of the literature about blockchain in supply chain management (SCM) context (blockchain-SCM integration) is presented and an agenda for future research is proposed.
Abstract: This paper aims to identify, analyse and organise the literature about blockchains in supply chain management (SCM) context (blockchain–SCM integration) and proposes an agenda for future research. This study aims to shed light on what the main current blockchain applications in SCM are, what the main disruptions and challenges are in SCM because of blockchain adoption and what the future of blockchains holds in SCM.,This study followed the systematic review approach to analyse and synthesise the extant literature on blockchain–SCM integration. The review analysed 27 papers between 2008 and 2018 in peer-reviewed journals.,Blockchain–SCM integration is still in its infancy. Scholars and practitioners are not fully aware of the potential of blockchain technology to disrupt traditional business models. However, the electric power industry seems to have a relatively mature understanding of blockchain–SCM integration, demonstrated by the use of smart contracts. Additionally, the disintermediation provided by blockchain applications has the potential to disrupt traditional industries (e.g. health care, transportation and retail).,The limitations of this study are represented mainly by the scarcity of studies on blockchain–SCM integration in leading journals and databases.,This study highlights examples of blockchain–SCM integration, emphasising the need to rethink business models to incorporate blockchain technology.,This study is the first attempt to synthesise existing publications about the blockchain–SCM integration, shedding light on the disruption caused by, and the necessity of, the SCM reconfigurations.
423 citations
References
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TL;DR: The Albanian Generals Problem as mentioned in this paper is a generalization of Dijkstra's dining philosophers problem, where two generals have to come to a common agreement on whether to attack or retreat, but can communicate only by sending messengers who might never arrive.
Abstract: I have long felt that, because it was posed as a cute problem about philosophers seated around a table, Dijkstra’s dining philosopher’s problem received much more attention than it deserves. (For example, it has probably received more attention in the theory community than the readers/writers problem, which illustrates the same principles and has much more practical importance.) I believed that the problem introduced in [41] was very important and deserved the attention of computer scientists. The popularity of the dining philosophers problem taught me that the best way to attract attention to a problem is to present it in terms of a story. There is a problem in distributed computing that is sometimes called the Chinese Generals Problem, in which two generals have to come to a common agreement on whether to attack or retreat, but can communicate only by sending messengers who might never arrive. I stole the idea of the generals and posed the problem in terms of a group of generals, some of whom may be traitors, who have to reach a common decision. I wanted to assign the generals a nationality that would not offend any readers. At the time, Albania was a completely closed society, and I felt it unlikely that there would be any Albanians around to object, so the original title of this paper was The Albanian Generals Problem. Jack Goldberg was smart enough to realize that there were Albanians in the world outside Albania, and Albania might not always be a black hole, so he suggested that I find another name. The obviously more appropriate Byzantine generals then occurred to me. The main reason for writing this paper was to assign the new name to the problem. But a new paper needed new results as well. I came up with a simpler way to describe the general 3n+1-processor algorithm. (Shostak’s 4-processor algorithm was subtle but easy to understand; Pease’s generalization was a remarkable tour de force.) We also added a generalization to networks that were not completely connected. (I don’t remember whose work that was.) I also added some discussion of practical implementation details.
5,208 citations
TL;DR: In this article, a group of generals of the Byzantine army camped with their troops around an enemy city are shown to agree upon a common battle plan using only oral messages, if and only if more than two-thirds of the generals are loyal; so a single traitor can confound two loyal generals.
Abstract: Reliable computer systems must handle malfunctioning components that give conflicting information to different parts of the system. This situation can be expressed abstractly in terms of a group of generals of the Byzantine army camped with their troops around an enemy city. Communicating only by messenger, the generals must agree upon a common battle plan. However, one or more of them may be traitors who will try to confuse the others. The problem is to find an algorithm to ensure that the loyal generals will reach agreement. It is shown that, using only oral messages, this problem is solvable if and only if more than two-thirds of the generals are loyal; so a single traitor can confound two loyal generals. With unforgeable written messages, the problem is solvable for any number of generals and possible traitors. Applications of the solutions to reliable computer systems are then discussed.
4,901 citations
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TL;DR: It is shown that, without a logically centralized authority, Sybil attacks are always possible except under extreme and unrealistic assumptions of resource parity and coordination among entities.
Abstract: Large-scale peer-to-peer systems face security threats from faulty or hostile remote computing elements. To resist these threats, many such systems employ redundancy. However, if a single faulty entity can present multiple identities, it can control a substantial fraction of the system, thereby undermining this redundancy. One approach to preventing these "Sybil attacks" is to have a trusted agency certify identities. This paper shows that, without a logically centralized authority, Sybil attacks are always possible except under extreme and unrealistic assumptions of resource parity and coordination among entities.
4,816 citations
"Blockchains and Smart Contracts for..." refers background in this paper
...Because of the Sybil attack [15], consensus in public networks is costly...
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...anyone can join though, this would be catastrophic because of the Sybil attack [15]: a single entity could join with multiple identities, get multiple votes, and thus influence the network to favor this entity’s interests....
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22 Feb 1999
TL;DR: A new replication algorithm that is able to tolerate Byzantine faults that works in asynchronous environments like the Internet and incorporates several important optimizations that improve the response time of previous algorithms by more than an order of magnitude.
Abstract: This paper describes a new replication algorithm that is able to tolerate Byzantine faults. We believe that Byzantinefault-tolerant algorithms will be increasingly important in the future because malicious attacks and software errors are increasingly common and can cause faulty nodes to exhibit arbitrary behavior. Whereas previous algorithms assumed a synchronous system or were too slow to be used in practice, the algorithm described in this paper is practical: it works in asynchronous environments like the Internet and incorporates several important optimizations that improve the response time of previous algorithms by more than an order of magnitude. We implemented a Byzantine-fault-tolerant NFS service using our algorithm and measured its performance. The results show that our service is only 3% slower than a standard unreplicated NFS.
3,562 citations
"Blockchains and Smart Contracts for..." refers background or methods in this paper
...5If more than 3f + 1 nodes are used, then the quorum thresholds listed in [26] may lead to forks....
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...Tendermint vs PBFT—Tendermint....
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...Sieve [38], a mechanism used in the HyperLedger Fabric project, augments the PBFT algorithm [26] by adding speculative execution and verification phases, inspired by the execute-verify architecture presented in [39]....
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...Tendermint [32] provides BFT tolerance and is similar to the PBFT algorithm; however it provides a tighter guarantee with regards to the results returned to the client when more than one third of the nodes are faulty, and allows for a dynamically changing set of set of validators, and leaders that can be rotated in a round-robin manner, among other optimizations [33]....
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...PBFT works on the assumption that less than one third of the nodes are faulty (f ), which is why say that it requires at least5 3f + 1 nodes....
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Proceedings Article•
19 Jun 2014TL;DR: Raft is a consensus algorithm for managing a replicated log that separates the key elements of consensus, such as leader election, log replication, and safety, and it enforces a stronger degree of coherency to reduce the number of states that must be considered.
Abstract: Raft is a consensus algorithm for managing a replicated log. It produces a result equivalent to (multi-)Paxos, and it is as efficient as Paxos, but its structure is different from Paxos; this makes Raft more understandable than Paxos and also provides a better foundation for building practical systems. In order to enhance understandability, Raft separates the key elements of consensus, such as leader election, log replication, and safety, and it enforces a stronger degree of coherency to reduce the number of states that must be considered. Results from a user study demonstrate that Raft is easier for students to learn than Paxos. Raft also includes a new mechanism for changing the cluster membership, which uses overlapping majorities to guarantee safety.
1,811 citations
"Blockchains and Smart Contracts for..." refers methods in this paper
...popular Raft algorithm [30], is used as a consensus mechanism in Juno [31]....
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