Multi-Tier Stack of Block Chain with Proxy Re-Encryption Method Scheme on the Internet of Things Platform

Blockchain is a developing technology which provides data storage, secure transactions and establishing trust in an open environment. Blockchain is widely implemented in cryptocurrency systems like Bitcoins, smart contracts, smart grids over IoT devices etc. Blockchain also has wide applications in healthcare, automobile industries, private and public sectors. This growing popularity of Blockchain is luring hackers to perform various cyber-attacks in order to detect vulnerabilities in the applied Blockchain system. A vulnerable block chain system is open for network breaches, data thefts and information manipulations. Therefore, it is important to design a Blockchain system with proper security, privacy and trust management. However, increasing security and privacy in Blockchain reduces its performance because security and privacy policies are overhead to the applied Blockchain system. Therefore, it is also important to optimize the performance of Blockchain system with proper implementation of security and privacy. This chapter discuss the current scenarios of security, privacy and trust issues in Blockchain. The chapter also discuss the proposed solutions regarding these issues. Further, the chapter discuss the performance analysis on increasing security and privacy in the Blockchain technology and proposed optimizations in the literature. This chapter is then conclude by providing few research directions for improving security, privacy and trust in Blockchain technology while keeping its performance optimized.

Blockchain technology as a means of sustainable development

The evolution of the business networks is fostering the demand for more connected devices to execute tangled and sophisticated business operations. This leverages complicated business networks space to include scalable network layers, more devices, and platforms relying on Internet of Things (IoT) solutions. Despite the fact that traditional IoT platforms usually target the technical side for IoT applications, they are not prepared enough to be easily integrated with pluggable and executable business logic or smart contracts. This makes it difficult to control a collection of shared business network resources in a standard and decentralized manner. With the rise of FinTech due to blockchain technology, it becomes possible to seamlessly engage business networks with financial digital assets. Consequently, combining IoT platforms with blockchain will drive new ways for better services consuming, transparency and products that depend on crowd-based economy [12]. In this paper, Sitechain is proposed as a new architecture to integrate IoT platforms with blockchain technology. The proposed architecture is not locked to specific IoT platforms but it can be extended to support different platforms in a standard, systematic and easy way. Sitechain is demonstrated by integrating Sitewhere and FIWARE IoT platforms with Hyperledger Fabric as a private blockchain network manager. Moreover a modeling language supported by Hyperledger composer is used to easily develop smart contracts and generate RESTful APIs, therefore any smart contract transaction events can be mapped into actions on remote devices. The system testing is performed using a large set of connected shared devices that are deployed as part of private business networks. The results are recorded in the conclusion section.

The Internet of Things (IoT) has been deployed in a vast range of applications with exponential increases in data size and complexity. Existing forensic techniques are not effective for the accuracy and detection rate of security issues in IoT forensics. Cyber forensic comprises huge volume constraints that are processing huge volumes of data in the Information and Communication Technology (ICT) comprised of IoT devices and platforms. Trust blockchain is effective technology those are utilized to assess the tamper-proof records in all transaction in the IoT environment. With the implementation of trust blockchain the record and transaction are processed with a distributed ledger that is managed by the network nodes. The challenge associated with the trust blockchain in IoT forensics is cost and security. To achieve significant cost-effectiveness organizations, need to evaluate the risks and benefits associated with IoT forensics in the trust blockchain technology. In this paper, developed a Block Chain Enabled Cyber-Physical system with distributed storage. The developed Blockchain model is termed as Integrated Hadoop Blockchain Forensic Machin Learning (IHBF-ML). The IHBF-ML model uses the Hadoop Distributed File System (HDFS) with cyberspace to improve security. Within the IHBF-ML model, IoT data communication is established with the smart contract. The smart contract-based blockchain process uses the Machine Learning model integrated with Cat Boost classification model for anomaly detection. Cost in IoT forensic is minimized with the parallel processing of the data through MapReduce Framework for the traffic translation, extraction, and analysis of the dynamic feature traffic from the IoT environment. The experimental analysis stated that constructed IHBF-ML model reduces the cost by ~25% than the other conventional blockchain Ethereum and EOS.

BackgroundThis paper explores the use of blockchain technology and smart contracts in the Internet of Medical Things (IoMT). It aims to identify the challenges and benefits of implementing smart contracts based on blockchain technology in the IoMT. It provides solutions and evaluates the IoMT uses in e-healthcare performance.MethodsA quantitative approach used an online survey from public and private hospital administrative departments in Dubai, United Arab Emirates (UAE). ANOVA, t-test, correlation, and regression analysis were performed to assess the e-healthcare performance with and without IoMT (smart contract based on blockchain).Patients and MethodsA mixed method was used in this research, a quantitative approach for data analysis utilizing online surveys from public and private hospitals’ administrative departments in Dubai, UAE. A correlation, regression through ANOVA, and independent two-sample t-test were performed to assess the e-healthcare performance with and without IoMT (smart contract based on blockchain).ResultsBlockchain application in smart contracts has proven to be significant in the healthcare sector. Results highlight the importance of integrating smart contracts and blockchain technology in the IoMT infrastructure to improve efficiency, transparency, and security. The study provides empirical evidence to support the implementation of smart contracts in the e-healthcare sector and suggests improved e-healthcare performance through this transition.ConclusionThe emergence of e-healthcare systems with upgraded smart contracts and blockchain technology brings continuous health monitoring, time-effective operations, and cost-effectiveness to the healthcare sector.

User privacy prevention model using supervised federated learning‐based block chain approach for internet of Medical Things

Due to the convergence of advanced technologies, the emergence of electronic things tends to increase tremendously. The Internet of Things (IoT) is the technology where enormous things such as sensors, softwares etc. are embedded together for enabling the connection as well as communication of data. With the evolution of Industrial IoT, the need for monitoring the things that are used for automation becomes one of the thrust among the industries. There is a necessity that the monitoring can be empowered through the integration of blockchain technology. Not limited to monitoring, it also enriches the scalability, interoperability, durability, device reliability, privacy, security, silo mentality, standardization of the devices that are used for the internet of things. The blockchain technology is the distributed ledger with the list of growing records or blocks which are linked using the cryptography. The one of the main advantage of blockchain technology is that all the transactions are captured with its respective timestamps and the data that are recorded in the blocks cannot be altered retroactively. This enforces timely updation of information which cannot be altered. The Industrial IoT plays a major roles in the IoT platform as there exists smart connected operations that covers plenty of assets which obviously needs capability such as high level connectivity, analytics on big data and the development of applications. To resolve these challenges of IIoT, several requirement has to be considered such as asset visibility, Bigdata handling, technology integration and security. Also it is felt that most of the existing facilities of the industries such as ad hoc networks, smart grids etc. could not connect to the IoT system as it is not with built in intelligence. These needs an interface for invoking the communication. Since the blockchain technology has the decentralized nature, the information of the communication that happens between the two devices such as state of the devices, interactions and data digest can be acquired all in a point. This might reduce the risk with the business processes that the industry faces. Also, in the field of logistics which is one of the most important field, the information about the goods will be kept out of the illegal persons. Hence, it is considered that the blockchain technology will hold a safer environment for the individual as well as the enterprises. Thus the integration of blockchain with the Internet of Things will regulate the process of IoT through decentralized control which is kept highly safe than other technology implications. This chapter discuss about the different components of block chain enabled IoT system and the application of implementing the blockchain in IoT.KeywordsBlockchainInternet of thingsIndustrial internet of thingsBlockchain and IoT

An internet of things (IoT) platform is a multi-layer technology that enables automation of connected devices within IoT. IoT platforms serve as a middle-ware solution and act as supporting software that is able to connect different hardware devices, access points, and networks to other parts of the value chain. Virtual objects have become a vital component in every IoT platform. Virtual objects are the digital representation of a physical entity. In this paper, we design and implement a cloud-centric IoT platform that serves a purpose for registration and initialization of virtual objects so that technology tinkerers can consume them via the IoT marketplace and integrate them to build IoT applications. The proposed IoT platform differs from existing IoT platforms in the sense that they provide hardware and software services on the same platform that users can plug and play. The proposed IoT platform is separate from the IoT marketplace where users can consume virtual objects to build IoT applications. Experiments are conducted for IoT platform and interworking IoT marketplace based on virtual objects in CoT. The proposed IoT platform provides a user-friendly interface and is secure and reliable. An IoT testbed is developed and a case study is performed for a domestic environment to reuse virtual objects on the IoT marketplace. It also provides the discovery and sharing of virtual objects. IoT devices can be monitored and controlled via virtual objects. We have conducted a comparative analysis of the proposed IoT platform with FIWARE. Results conclude that the proposed system performs marginally better than FIWARE.

Internet of Things (IoT) platforms are the key for the development of scalable IoT applications and services that connect real and virtual worlds between objects, systems, and people. However, as the IoT platform market represents a truly new market segment that was almost non-existent a few years ago, the platforms are complex and changing quickly. These IoT platforms perform simple functions such as providing useful information, and others can provide services through collaborations with IoT devices. This situation needs a generic service interface, and results in a range of IoT architectures through not only the configuration setting of IoT devices and resources but also the varied environments of collaboration of each device. Due to these heterogeneities, it is quite challenging to develop applications working with diverse IoT services, and it is even more difficult to maintain such applications. Therefore, this paper presents a security generic service interface with the effective common characteristics of an IoT platform by defining a set of generic interfaces and adopting well-known design patterns. The generic interface solves the heterogeneity-driven problems and makes it possible to effectively adopt a platform-independent Generic Interface that could be operated in diverse IoT platforms.

In this technology era, the Internet of Things (IoT) plays predominant role in several aspects of real-life problem. The thrust area of IoT applications include smart city, smart transport, smart healthcare, smart environment, smart agriculture, etc. The IoT system involves heterogeneous sensors and devices at the edge layer of the protocol stack. These IoT devices are characterized in term of hardware specification, different communication protocols, services offered by these devices and trustable users of the IoT devices. Hence, the IoT requires efficient security and privacy mechanism for heterogeneous IoT devices and as well as voluminous amount of data generated by these IoT devices. Conventionally, the security for homogenous devices is provided by the centralized mechanism through authentication, encryption/decryption of data, digital signatures and cryptographic algorithms. However, IoT has characteristics of heterogeneous, autonomous and resource constraint IoT devices, in which case, the conventional centralized security solutions fail tremendously. Hence, the decentralized approach of Block chain is well suited for this scenario. This chapter targets to provide the comprehensive review of various security, privacy and access issues, solution approaches and challenges towards IoT. The role block chains in five different IoT applications are discussed in this chapter. These IoT applications include Intelligence Transport system, Smart Healthcare system, supply chain management, IoT ecosystem, Smart City. This chapter discusses how block chain provides security, smart contracts, access control and proof-of-work and proof-of-state are carried out at decentralized manner. The chapter presents the use case of block chain beyond crypto currency and bit coin, the data are to be preserved through block chain technique and different mining techniques used in block chain for these IoT applications.

Introduction to the Special Issue on Evolving IoT and Cyber-Physical Systems: Advancements, Applications, and Solutions

One of the key advancements in the development of smart grids is the use of transactive energy, which utilizes distributed energy resources like smart grids Contributions In today’s industrial era, where technology is developing very quickly, it is essential to use electricity as needed to prevent loss, waste, and supply shortages "Smart Electric" or "Smart Grid" design is strongly advised in this situation The following advantages in terms of cost-effectiveness are anticipated: Large enough for even technical solutions to be taken into account. This will be implemented extensively by key electricity companies Utilizing transactive energy in a smart grid, however, introduces new security issues such unauthorized energy transfers Novelty This study proposes a Blockchain based smart contract architecture with fully decentralized capabilities for dependable and inexpensive transactive energy. The Blockchain, which has a high replication rate and provides stronger security against manipulation, is used to record energy transaction data These enhancements can be made via Blockchain technology Blockchain technology is confirmed as a promising option to raise the share of renewable energy after the development of renewable energy and how it interacts with Blockchain technology are examined. The various Blockchain applications in are then divided into various categories, including smart contracts and Demand Response (DR), Electric Vehicles (EV), the Internet of Things (IoT), decentralized energy management, energy trading, financial transactions, and cyber security testbeds, as well as environmental concerns The energy auction is run in accordance with transparent rules that are implemented as a smart contract, making it accessible to all parties Threats resulting from known smart meter vulnerabilities are decreased by temporarily limiting vulnerable prosumers’ access to smart meters and updating their devices as soon as security solutions are available.

The Internet of Things (IoT) technologies are transforming traditional businesses into digital-based platforms allowing for more service innovation, performance efficiency and customer satisfaction. Novel services enable users to utilize their personal devices (eg. mobile phones or laptops) to access the IoT platform, process data, and control the IoT infrastructure. However, these services impose critical user authentication and access control requirements. In this paper, we propose a decentralized user authentication and access control system for the IoT platforms via a permissioned blockchain network. We define an authorization sensitivity factor to provide clients with specific access control privileges and we consider an ehealth system as a use case example to demonstrate our solution. The proposed system is implemented using Ethereum platform. Besides, we investigate a threat model that considers an insider Distributed Denial of Service (DDoS) attack. The proposed defense mechanism utilizes a modifier function in the smart contract and keeps a real-time record of legitimate users to restrict function calls. The results illustrate the benefits of the defense mechanism in terms of the system response time.

Blockchain technologies offer transformative potential in terms of addressing the security, trust, and identity management issues that exist in large-scale Internet of Things (IoT) deployments. This narrative review provides a comprehensive survey of various studies, focusing on decentralized identity management, trust mechanisms, smart contracts, privacy preservation, and real-world IoT applications. According to the literature, blockchain-based solutions provide robust authentication through mechanisms such as Physical Unclonable Functions (PUFs), enhance transparency via smart contract-enabled reputation systems, and significantly mitigate vulnerabilities, including single points of failure and Sybil attacks. Smart contracts enable secure interactions by automating resource allocation, access control, and verification. Cryptographic tools, including zero-knowledge proofs (ZKPs), proxy re-encryption, and Merkle trees, further improve data privacy and device integrity. Despite these advantages, challenges persist in areas such as scalability, regulatory and compliance issues, privacy and security concerns, resource constraints, and interoperability. By reviewing the current state-of-the-art literature, this review emphasizes the importance of establishing standardized protocols, performance benchmarks, and robust regulatory frameworks to achieve scalable and secure blockchain-integrated IoT solutions, and provides emerging trends and future research directions for the integration of blockchain technology into the IoT ecosystem.

Citation (2021), "A Glossary of Blockchain Terms* ", Baker, H.K., Nikbakht, E. and Smith, S.S. (Ed.) The Emerald Handbook of Blockchain for Business, Emerald Publishing Limited, Bingley, pp. 373-381. https://doi.org/10.1108/978-1-83982-198-120211028 Publisher: Emerald Publishing Limited Copyright © 2021 by Emerald Publishing Limited Airdrop An airdrop is a distribution of a cryptocurrency token or coin, usually for free, to numerous wallet addresses for marketing purposes. Atomic swap An atomic swap is a smart contract technology enabling the exchange of one cryptocurrency for another without using centralized intermediaries. Bitcoin Bitcoin is a type of digital currency that runs on the peer-to-peer (P2P) network without the need for central authority or intermediaries. Block A block is a collection of transactions that has not yet been recorded in any prior blocks. Blockchain A blockchain is a decentralized public ledger that uses cryptography to record transactions among a network's participating agents. It permits transactions to be gathered into blocks and recorded cryptographically into chain blocks in chronological order, and allows all users in the network to access the ledger. A central authority does not own, control, or manage this distributed database. Blockchain application A blockchain application is a P2P system for validating, time stamping, and permanently storing transactions and agreements on a shared ledger that is distributed to all participating nodes. Byzantine fault tolerance (BFT) BFT is the property of a system that can resist the class of failures derived from the Byzantine Generals' Problem, which is a logical dilemma that illustrates how a group of Byzantine generals may have communication problems when trying to agree on their next move. Thus, a BFT system can continue to operate even if some of the nodes fail or act maliciously. Central bank digital currency (CBDC) A CBDC is fiat money of a particular nation or region, issued and regulated by a country's monetary authority. Thus, CBDC is money that a government establishes and backs through its central bank in a virtual form. Cold wallet A cold wallet is a component of hardware or other type of physical device that enables investors to access crypto-asset holdings. Consensus protocol (algorithm or mechanism) Consensus protocol is the set of rules and mechanisms implemented in a blockchain to consolidate the preferences and decisions of users and to manage decision-making of the network. It determines how users reach consensus on that blockchain in achieving the necessary agreement on a single data value or a single state of the network among distributed processes. Consortium blockchain A consortium blockchain is a system that is “semiprivate” with a controlled user group, but works across different organizations. The protocol layer is under the control of a consortium of firms that must govern according to legal frameworks and agreements external to the blockchain code. A consortium blockchain is a hybrid between the “low trust” offered by public blockchains and the “single highly trusted entity” model of private blockchains. Thus, a consortium blockchain is permissioned, semidecentralized, and has a multiparty consensus. Crosschain A crosschain is the interoperability between two relatively independent blockchains. It enables blockchains to speak to one another because they are built in a standardized way. Cryptocurrency A cryptocurrency is a digital or virtual currency that uses encryption techniques to regulate the generation of units of currency and verify the transfer of funds. It operates independently of a central bank. Many cryptocurrencies such as bitcoin are decentralized networks based on blockchain technology. Cryptocurrency agnostic Cryptocurrency agnostic means that projects are built to work with a multitude of tokens, cryptos, and altcoins, which allow users from different ecosystems to participate, further expanding building capacity across existing and new cryptocurrency projects. Cryptoeconomics Cryptoeconomics is using incentives and cryptography to design new kinds of systems, applications, and networks. It also studies economic interaction in adversarial environments. Cryptographic hashing Cryptographic hashing is the procedure of repeatedly inserting a random string of digits into hashing formula until finding a desirable output. It produces a single fixed length output. Some examples of hash function algorithms are MD5, MD4, or SHA-256. Cypherpunk A cypherpunk is someone who believes in privacy-enhancing technology. Cryptography Cryptography is a mathematical algorithm used to encrypt and decrypt information. In blockchain, it is used for creating wallets, signing transactions, and verifying the block. Crypto tokens A crypto token, also called a cryptocurrency or crypto asset, is a special kind of virtual currency token residing on its own blockchain and representing an asset or utility. Decentralized application (dApp) A decentralized application is a computer application that runs on a distributed computing system. Decentralized autonomous organization (DAO) A DAO is a virtual organization embodied in computer code and executed on a distributed ledger or blockchain. Decentralized network A decentralized network refers to a network in which anyone can transact on the ledger. The network is decentralized in the sense that no centralized entity governs the network. Delegated Proof of Stake (DPoS) DPoS is a consensus protocol that provides dependable verification and approval of transactions in a blockchain. Distributed hash table (DHT) DHT is a key-value store where the keys are hashes and widely used to coordinate and maintain metadata about P2P systems. Key-value pairs are stored in a DHT, and any participating node can efficiently retrieve the value associated with a given key. Distributed ledger A distributed ledger is a database that is shared across multiple sites or geographies accessible by multiple people. It allows transactions to open to the participants publicly. The participant at each node of the network can access the records shared across that network and can own an identical copy of it. Any changes or additions made to the ledger are reflected and copied to all participants. Double spending Double spending is the result of successfully spending digital currency more than once. Blockchain protects against double spending by verifying each transaction in the network. It ensures that the inputs for the transaction had not previously already been spent. Encryption Encryption refers to the process of converting data to an unrecognizable or “encrypted” form. A common use of encryption is to protect sensitive information, so that only authorized parties can view it. Blockchain encryption prevents sensitive information from getting into the wrong hands and being misused or forged. Thus, only authorized parties can view the information. Although various blockchains use different cryptography algorithms, the Bitcoin blockchain uses the SHA-256 algorithm, which produces a 32-byte hash that has proven resistant to hacking attempts to date. Genesis block Genesis block is the name of a blockchain's first block. It is the prototype of all other blocks in the blockchain as the common ancestor of them. If any block is followed the chain backward in time, it eventually leads to the genesis block. Hard fork A hard fork occurs when a cryptocurrency on a distributed ledger undergoes a protocol change resulting in a permanent diversion from the legacy or existing distributed ledger. This radical change to the protocol of a blockchain network makes previously invalid blocks/transactions valid or vice versa. Thus, a hard fork is a backward incompatible upgrade to the blockchain network. Hashing Hashing is a mathematical function that miners perform on blocks to make the network secure. It is a transaction's unique identifier. Hash rate Hash rate is the computational power that miners contribute to secure the network in exchange for block rewards and transaction fees. Hot wallet A hot wallet is an online portal that allows investors or merchants to access crypto holdings via an online platform or application. Hybrid blockchain A hybrid blockchain is a mix of public and private blockchains. It can host an application or service on an independent permissioned blockchain while leveraging a public blockchain for security and settlement. Hybrid PoW (Proof of Work)/PoS (Proof of Stake) A hybrid PoW/PoS consensus mechanism uses elements of both PoW and PoS models when determining transaction validation rights. Hyperledger Hyperledger is an open source blockchain project designed to promote collective advancement of blockchain projects as opposed to disparate proprietary systems. Immutability Immutability is the inability of a block to be deleted or modified once it is in the blockchain. Initial coin offering (ICO) An ICO is a mechanism used to raise external funding through the emission of tokens in exchange for cryptocurrencies. It is often a form of crowdfunding, but a private ICO that does not seek public investment is also possible. Interoperability Interoperability refers to the exchange of data and information compatibly across varied complex systems. InterPlanetary File System (IPFS) IPFS is a protocol and P2P network for storing and sharing data in a distributed file system. Lightning network A lightning network is a series of off-chain payment channels where two people can conduct a very fast low-cost transaction or series of transactions, which are later settled on-chain. It adds another layer to Bitcoin's blockchain enabling users to create payment channels between any two parties on that extra layer. Merkle (hash) tree and root A Merkle tree or hash tree is a tree-like structure that organizes large amounts of data using hashes. It consists of raw data, leaves, and a root. In blockchain, a Merkle tree serves to encode data and to verify it as blockchain signatures (hashing) more efficiently and securely. A Merkle root is the hash of all the hashes of all the transactions that are part of a block in a blockchain network. Miner A miner is a node on the network that is actively involved in the consensus process used to verify transactions before these transactions are batched in blocks. Miners participate in performing the block verification process by determining whether each transaction is legitimate. Miners are incentivized to participate in this process with the ability to earn compensation from either confirming blocks as they are added to the blockchain or processing transactions. Mining Mining is the process of adding new transaction records to a block and verifying a block created by other miners. It allows nodes to reach a secure, tamper-resistant consensus. Miners collect transaction fees and are rewarded for their services. Node A node is any kind of device such as a computer, laptop, or server that connects to the blockchain network. It stores, spreads, and preserves the blockchain data. All nodes on a blockchain network are connected and constantly exchange the latest data with each other. Nonce A nonce, an abbreviation for “number only used once,” is a pseudo-random number that is used as a counter during the mining process. It is a number added to a hashed or encrypted block in a blockchain that, when rehashed, meets the difficulty level restrictions. Thus, a nonce is the number that blockchain miners are trying to solve. Off-chain transaction Off-chain refers to a cryptocurrency transaction that happens outside of a main blockchain and is not published there. On-chain transaction On-chain refers to a cryptocurrency transaction that occurs on the blockchain. Oracle An oracle is a way for a blockchain or smart contract to interact with external data. As third-party services, blockchain oracles serve as bridges between blockchains and the outside world. Orphan block An orphan block is a validated block that is not accepted into the blockchain network due to a time lag in the acceptance of the block in question into the blockchain.For example, assume two blocks are validated at a similar time. Once one block gets accepted in the node, then the other block is discarded, which is an orphan block. Thus, an orphan block is a valid and verified block but have been rejected by the chain Peer-to-peer (P2P) In blockchain, a P2P network is one where peers can communicate and do transactions directly with other network members without having to rely on an intermediary or a third party to perform confirmations or other verification processes Private (permissioned) blockchain A private blockchain is closed and invitation-only such that specific users or entities on a blockchain have authorizing powers over others, allowing them to appoint members or validators. It has centralized authorities and is often deployed in the area of internal business operations. Private key A private key is a cryptography allowing a user access to his or her cryptocurrency or transaction. It is equivalent to a password and thereby helps to protect a user from theft and unauthorized access to funds. Proof of Activity (PoA) POA is another hybrid of PoW and PoS that attempts to combine the best features of both mechanisms. Proof of Burn (PoB) POB is an alternative consensus algorithm that tries to address the high energy consumption issue of a PoW system. Proof of Capacity (PoC) POC is a consensus mechanism that uses a process called plotting. Programmatic Proof of Work (ProgPoW) ProgPow is a blockchain protocol consensus algorithm designed to reduce the mining efficiency advantage of specialized hardware like ASIC miners over less-advanced machines like a standard CPU, meaning average individual crypto participants can mine coins. Proof of Elapsed Time (PoET) PoET is a consensus algorithm that prevents high resource utilization and keeps the process more efficient by following a fair lottery system. For example, each participating node in the network is required to wait for a randomly chosen time period, and the first one to complete the designated waiting time wins the new block. Each node in the blockchain network generates a random wait time and goes to sleep for that specified duration. The one with the shortest wait time commits a new block to the blockchain, broadcasting the necessary information to the whole peer network. The same process then repeats for the discovery of the next block. Proof of Retrievability (PoR) PoR is a compact proof by a file system (prover) to a client (verifier) that a target file is intact in the sense that the client can fully recover it. Proof of Storage Proof of Storage is a consensus protocol used primarily to verify the integrity of a remote file. Proof of Work (PoW) PoW is the original consensus algorithm in a blockchain network. In a PoW algorithm, the miners compete against each other to validate a block and the first miner who presents validation for a block gets rewarded. For example, a miner repeatedly inserts transaction data (block) and a random string of digits (nonce of block) into a hashing formula, until the miner finds a desirable outcome ‒ the PoW. Other miners can verify the PoW by taking the alleged input string and applying it to the same formula to see if the outcome is what the initial minor presented. Some view PoW as a controversial consensus algorithm because of the electricity costs involved in performing the formula calculations. Proof of Stake (PoS) PoS is a consensus algorithm that asks users to prove ownership of a certain amount of currency that is their stake in the currency. PoS gives the miners who hold coins (e.g., bitcoin) the ability to mine or validate transactions. In other words, the power of mining is proportional to the amount of coins a miner owns. Thus, the PoS process rewards larger stakeholders in the network. Public (permissionless) blockchain A public or permissionless blockchain is a decentralized ledger that is accessible to any user. Users do not need permission from anyone on the network to perform certain actions such as joining the network, receiving/sending transaction data, and participating in the consensus process to determine what blocks get added to the chain. Public key A public key is a cryptographic code or address used to facilitate transactions between parties that allow users to receive cryptocurrencies in their accounts. It enables the agent to access specific information, comparable to an access code. Record A record is a combination of transactions. SHA-256 SHA-256 stands for Secure Hash Algorithm 256-bit, and it is used for cryptographic security. SHA-256 generates an almost-unique 256-bit signature for a text. Bitcoin uses SHA-256 for mining and creating addresses. Sidechain A sidechain is a mechanism allowing tokens and other digital assets from one blockchain to be securely used in a separate blockchain and then be moved back to the original blockchain if needed. Smart contract A smart contract is computer code operationalized within blockchain that automatically moves digital assets according to prespecified rules. Thus, smart contracts are codes that are built into the software that enable automation of certain job tasks or processes. Soft fork A soft fork is a change to the bitcoin protocol that makes only previously valid blocks or transactions invalid. Stablecoin A stablecoin is a crypto asset that normally takes the form of a coin or token that is connected or supported by an underlying asset including currencies or basket of commodities. The basic goal of stablecoins is to aid in developing of an alternative financial system with currency units not dependent or controlled by a government or other centralized entity. Stale block A stale block is a block that is no longer part of the current best blockchain because it was overridden by a longer chain. Tamper-resistant ledger A tamper-resistant or immutable ledger is a record (data stored on the blockchain) that cannot be changed due to using of encryption and digital signatures. Wallet A wallet is the primary storage platform for crypto assets. *H. Kent Baker and Hak J. Kim compiled this glossary. Book Chapters Prelims Part I Blockchain: History and Background Chapter 1 Blockchain: An Overview Chapter 2 History of Blockchain Chapter 3 Review of Blockchain and Emerging Applications Chapter 4 Technical Aspects of Blockchain Part II Types of Blockchain and Related Issues Chapter 5 Public Blockchains and Applications Chapter 6 Private and Hybrid Blockchains and Applications Chapter 7 Consensus Mechanisms and Related Issues Chapter 8 Token Economies Chapter 9 Proposed Modifications to Spur Consumer Adoption of Blockchain Part III The Frontier of Blockchain Technology Chapter 10 Blockchain: Speed, Efficiency, Decreased Costs, and Technical Challenges Chapter 11 The Importance of Interoperability, Decentralization, and Choice Chapter 12 Convergence with Artificial Intelligence and Other Related Concepts Chapter 13 Risk Management and Transference Issues in Blockchain Technologies Chapter 14 Legal and Regulatory Issues in the Temporary Regime Chapter 15 Regulatory Ambiguity and Its Impact on Blockchain Part IV Blockchain Applications in Business Chapter 16 Considerations for Blockchain Adoption and Integration Chapter 17 Blockchain Applications in Finance Chapter 18 Blockchain Applications in Healthcare Chapter 19 Blockchain Applications in Real Estate Chapter 20 Blockchain Applications in Supply Chain Chapter 21 Crypto Accounting Valuation, Reporting, and Disclosure Chapter 22 Auditing and Examining Blockchain Information A Glossary of Blockchain Terms Discussion Questions and Answers (Chapters 2–22) Index