The blockchain technology has revolutionized the digital currency space with the pioneering cryptocurrency platform named Bitcoin. From an abstract perspective, a blockchain is a distributed ledger capable of maintaining an immutable log of transactions happening in a network. In recent years, this technology has attracted significant scientific interest in research areas beyond the financial sector, one of them being the Internet of Things (IoT). In this context, the blockchain is seen as the missing link toward building a truly decentralized, trustless, and secure environment for the IoT and, in this survey, we aim to shape a coherent and comprehensive picture of the current state-of-the-art efforts in this direction. We start with fundamental working principles of blockchains and how blockchain-based systems achieve the characteristics of decentralization, security, and auditability. From there, we build our narrative on the challenges posed by the current centralized IoT models, followed by recent advances made both in industry and research to solve these challenges and effectively use blockchains to provide a decentralized, secure medium for the IoT.

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Applications of Blockchains in the Internet of Things: A Comprehensive Survey

https://researchrepository.ucd.ie/bitstream/10197/12102/2/Survey_on_Smart_Contracts____JNCA__2nd_Revision_CleanDocument%20%282%29.pdf

Survey on blockchain based smart contracts: Applications, opportunities and challenges

Industry 4.0 has paved the way for a world where smart factories will automate and upgrade many processes through the use of some of the latest emerging technologies. One of such technologies is Unmanned Aerial Vehicles (UAVs), which have evolved a great deal in the last years in terms of technology (e.g., control units, sensors, UAV frames) and have significantlyr educed their cost. UAVs can help industry in automatable and tedious tasks, like the ones performed on a regular basis for determining the inventory and for preserving item traceability. In such tasks, especially when it comes from untrusted third parties, it is essential to determine whether the collected information is valid or true. Likewise, ensuring data trustworthiness is a key issue in order to leverage Big Data analytics to supply chain efficiency and effectiveness. In such a case, blockchain, another Industry 4.0 technology that has become very popular in other fields like finance, has the potential to provide a higher level of transparency, security, trust and efficiency in the supply chain and enable the use of smart contracts. Thus, in this paper, we present the design and evaluation of a UAV-based system aimed at automating inventory tasks and keeping the traceability of industrial items attached to Radio-Frequency IDentification (RFID) tags. To confront current shortcomings, such a system is developed under a versatile, modular and scalable architecture aimed to reinforce cyber security and decentralization while fostering external audits and big data analytics. Therefore, the system uses a blockchain and a distributed ledger to store certain inventory data collected by UAVs, validate them, ensure their trustworthiness and make them available to the interested parties. In order to show the performance of the proposed system, different tests were performed in a real industrial warehouse, concluding that the system is able to obtain the inventory data really fast in comparison to traditional manual tasks, while being also able to estimate the position of the items when hovering over them thanks to their tag's signal strength. In addition, the performance of the proposed blockchain-based architecture was evaluated in different scenarios.

Towards an Autonomous Industry 4.0 Warehouse: A UAV and Blockchain-Based System for Inventory and Traceability Applications in Big Data-Driven Supply Chain Management.

Internet of Things (IoT) and blockchain technologies are being heavily exploited and used in may domains, especially for e-healthcare. In healthcare, IoT devices have the ability to provide real-time sensory data from patients to be processed and analyzed. Collected IoT data are subjected to centralized computation, processing, and storage. Such centralization can be problematic, as it can be a single point of failure, mistrust, data manipulation and tampering, and privacy evasion. Blockchain can solve such serious problems by providing decentralized computation and storage for IoT data. Therefore, the integration IoT and blockchain technologies can become a reasonable choice for the design of a decentralized IoT-based e-healthcare systems. In this article, first, we give a brief background on blockchain. Second, popular consensus algorithms used in blockchain are discussed in the context of e-health. Third, blockchain platforms are reviewed for their appropriateness in IoT-based e-healthcare. Finally, few use cases are methodologically given to show how key features of the IoT and blockchain can be leveraged to support healthcare services and ecosystems. We also propose a data-flow architecture that combines the IoT with blockchain, called IoBHealth , that can be used for storing, accessing, and managing of e-healthcare data.

Blockchain for IoT-Based Healthcare: Background, Consensus, Platforms, and Use Cases

Recently, with the rapid development of information and communication technologies, the infrastructures, resources, end devices, and applications in communications and networking systems are becoming much more complex and heterogeneous. In addition, the large volume of data and massive end devices may bring serious security, privacy, services provisioning, and network management challenges. In order to achieve decentralized, secure, intelligent, and efficient network operation and management, the joint consideration of blockchain and machine learning (ML) may bring significant benefits and have attracted great interests from both academia and industry. On one hand, blockchain can significantly facilitate training data and ML model sharing, decentralized intelligence, security, privacy, and trusted decision-making of ML. On the other hand, ML will have significant impacts on the development of blockchain in communications and networking systems, including energy and resource efficiency, scalability, security, privacy, and intelligent smart contracts. However, some essential open issues and challenges that remain to be addressed before the widespread deployment of the integration of blockchain and ML, including resource management, data processing, scalable operation, and security issues. In this paper, we present a survey on the existing works for blockchain and ML technologies. We identify several important aspects of integrating blockchain and ML, including overview, benefits, and applications. Then we discuss some open issues, challenges, and broader perspectives that need to be addressed to jointly consider blockchain and ML for communications and networking systems.

Blockchain and Machine Learning for Communications and Networking Systems

The Internet of Things (IoT) has already reshaped and transformed our lives in many ways ranging from how we communicate with people or manage our health to how we drive our cars and manage our homes. With the rapid development of the IoT ecosystem in a wide range of applications, IoT devices and data are going to be traded as commodities in the marketplace in near future, similar to cloud services or physical objects. Developing such a trading platform has previously been identified as one of the key grand challenges in integration of IoT and data science in this column. Deployment of such a platform obviously raises public concerns on the security and privacy of both data and devices since their ownerships are hard to trace and manage without a central trusted authority. The central trusted authority is not a viable solution for a fully decentralised and distributed IoT ecosystem with a large number of distributed device vendors and consumers who do not trust each other. Blockchain, as a decentralised system, removes the requirement for a trusted third party by allowing all participants to verify the correctness of the data and ensure their immutability. IoT devices can use blockchain to register themselves and organize, store and share streams of data from them effectively and reliably. In this article, through a case study, we demonstrate the applicability of blockchain in IoT devices and their data management with an aim of providing end-to-end trust for trading. We also give a brief introduction to the topics and challenges for future research towards addressing a grand challenge, i.e. developing a trustworthy trading platform for IoT ecosystems.

IoTChain: Establishing Trust in the Internet of Things Ecosystem Using Blockchain

Cryptographic techniques are employed to ensure the security of voting systems in order to increase its wide adoption. However, in such electronic voting systems, the public bulletin board that is hosted by the third party for publishing and auditing the voting results should be trusted by all participants. Recently a number of blockchain-based solutions have been proposed to address this issue. However, these systems are impractical to use due to the limitations on the voter and candidate numbers supported, and their security framework, which highly depends on the underlying blockchain protocol and suffers from potential attacks (e.g., force-abstention attacks). To deal with two aforementioned issues, we propose a practical platform-independent secure and verifiable voting system that can be deployed on any blockchain that supports an execution of a smart contract. Verifiability is inherently provided by the underlying blockchain platform, whereas cryptographic techniques like Paillier encryption, proof-of-knowledge, and linkable ring signature are employed to provide a framework for system security and user-privacy that are independent from the security and privacy features of the blockchain platform. We analyse the correctness and coercion-resistance of our proposed voting system. We employ Hyperledger Fabric to deploy our voting system and analyse the performance of our deployed scheme numerically.

Platform-Independent Secure Blockchain-Based Voting System

Proof-of-QoS: QoS based blockchain consensus protocol

Payment channel networks (PCNs) have been proposed to address the low transaction throughput of the permissionless blockchain protocols. Though the PCNs allow users to have the unlimited number of transactions in the channel without interacting with blockchain, it leaks the entire payment paths to the public. To address the payment path leakage issue, we propose a Chameleon-hash based payment protocol, called Chameleon Hash Time-Lock Contract (CHTLC). Using Chameleon-hash function in a multi-layer fashion guarantees that no user can recover the payment path if at least one intermediate payment node is honest. For the same payment path, compared with Multi-hop Hash Time-Lock Contract (MHTLC) protocol of Malavolta et al. [1], CHTLC is 5 times faster in the payment data initialisation, and the communication bandwidth is reduced significantly from 17, 000 KB to just 7.7 KB.

Chameleon Hash Time-Lock Contract for Privacy Preserving Payment Channel Networks

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Bin Yu

Papers

IoTChain: Establishing Trust in the Internet of Things Ecosystem Using Blockchain

Platform-Independent Secure Blockchain-Based Voting System

Proof-of-QoS: QoS based blockchain consensus protocol

Chameleon Hash Time-Lock Contract for Privacy Preserving Payment Channel Networks

Platform-independent Secure Blockchain-Based Voting System.