SoK: Exploring Blockchains Interoperability

Distributed ledger technologies like blockchain have gained great attention in both academia and industry. Blockchain as a potentially disruptive technology can advance many different fields, e.g., cryptocurrencies, supply chains, and the industrial Internet of Things. The next-generation blockchain ecosystem is expected to consist of various homogeneous and heterogeneous distributed ledgers. These ledger systems will inevitably require a certain level of proper cooperation of multiple blockchains to enrich advanced functionalities and enhance interoperable capabilities for future applications. The interoperability among blockchains will definitely revolutionize current blockchain design principles, like the emergence of Internet. The development of cross-blockchain applications involves much complexity regarding the variety of underlying cross-blockchain communication. The way to effectively enable interoperability across multiple blockchains is thus essential and expecting to confront various unprecedented challenges. For instance, due to different transaction structures, ensuring the properties of ACID (Atomicity, Consistency, Isolation, Durability) in transactions processing and verification processes across diverse blockchain systems remains a challenging task in both academia and industry. This paper provides a systematic and comprehensive review of the current progress of blockchain interoperability. We explore both general principles and practical schemes to achieve interoperable blockchain systems. We then survey and compare the state-of-the-art solutions to deal with the interoperability of blockchains in detail. Finally, we discuss several critical challenges and some potential research directions to advance the research on exploring blockchain interoperability

Data trust framework using blockchain and smart contracts

Lack of trust is the main barrier preventing more widespread data sharing. The lack of transparent and reliable infrastructure for data sharing prevents many data owners from sharing their data. Data trust is a paradigm that facilitates data sharing by forcing data controllers to be transparent about the process of sharing and reusing data. Blockchain technology has the potential to present the essential properties for creating a practical and secure data trust framework by transforming current auditing practices and automatic enforcement of smart contracts logic without relying on intermediaries to establish trust. Blockchain holds an enormous potential to remove the barriers of traditional centralized applications and propose a distributed and transparent administration by employing the involved parties to maintain consensus on the ledger. Furthermore, smart contracts are a programmable component that provides blockchain with more flexible and powerful capabilities. Recent advances in blockchain platforms toward smart contracts' development have revealed the possibility of implementing blockchain-based applications in various domains, such as health care, supply chain and digital identity. This dissertation investigates the blockchain's potential to present a framework for data trust. It starts with a comprehensive study of smart contracts as the main component of blockchain for developing decentralized data trust. Interrelated, three decentralized applications that address data sharing and access control problems in various fields, including healthcare data sharing, business process, and physical access control system, have been developed and examined. In addition, a general-purpose application based on an attribute-based access control model is proposed that can provide trusted auditability required for data sharing and access control systems and, ultimately, a data trust framework. Besides auditing, the system presents a transparency level that both access requesters (data users) and resource owners (data controllers) can benefit from. The proposed solutions have been validated through a use case of independent digital libraries. It also provides a detailed performance analysis of the system implementation. The performance results have been compared based on different consensus mechanisms and databases, indicating the system's high throughput and low latency. Finally, this dissertation presents an end-to-end data trust framework based on blockchain technology. The proposed framework promotes data trustworthiness by assessing input datasets, effectively managing access control, and presenting data provenance and activity monitoring. A trust assessment model that examines the trustworthiness of input data sets and calculates the trust value is presented. The number of transaction validators is defined adaptively with the trust value. This research provides solutions for both data owners and data users’ by ensuring the trustworthiness and quality of the data at origin and transparent and secure usage of the data at the end. A comprehensive experimental study indicates the presented system effectively handles a large number of transactions with low latency

Patterns for Blockchain Data Migration

With the rapid evolution of technological, economic, and regulatory landscapes, contemporary blockchain platforms are all but certain to undergo major changes. Therefore, the applications that rely on them will eventually need to migrate from one blockchain instance to another to remain competitive and secure, as well as to enhance the business process, performance, cost efficiency, privacy, and regulatory compliance. However, the differences in data and smart contract representations, modes of hosting, transaction fees, as well as the need to preserve consistency, immutability, and data provenance introduce unique challenges over database migration. We first present a set of blockchain migration scenarios and data fidelity levels using an illustrative example. We then present a set of migration patterns to address those scenarios and the above data management challenges. Finally, we demonstrate how the effort, cost, and risk of migration could be minimized by choosing a suitable set of data migration patterns, data fidelity level, and proactive system design. Practical considerations and research challenges are also highlighted.Comment: 40 pages, 13 figures, 1 tabl

SoK: Tokenization on Blockchain

Blockchain, a potentially disruptive technology, advances many different applications, e.g., crypto-currencies, supply chains, and the Internet of Things. Under the hood of blockchain, it is required to handle different kinds of digital assets and data. The next-generation blockchain ecosystem is expected to consist of numerous applications, and each application may have a distinct representation of digital assets. However, digital assets cannot be directly recorded on the blockchain, and a tokenization process is required to format these assets. Tokenization on blockchain will inevitably require a certain level of proper standards to enrich advanced functionalities and enhance interoperable capabilities for future applications. However, due to specific features of digital assets, it is hard to obtain a standard token form to represent all kinds of assets. For example, when considering fungibility, some assets are divisible and identical, commonly referred to as fungible assets. In contrast, others that are not fungible are widely referred to as non-fungible assets. When tokenizing these assets, we are required to follow different tokenization processes. The way to effectively tokenize assets is thus essential and expecting to confront various unprecedented challenges. This paper provides a systematic and comprehensive study of the current progress of tokenization on blockchain. First, we explore general principles and practical schemes to tokenize digital assets for blockchain and classify digitized tokens into three categories: fungible, non-fungible, and semi-fungible. We then focus on discussing the well-known Ethereum standards on non-fungible tokens. Finally, we discuss several critical challenges and some potential research directions to advance the research on exploring the tokenization process on the blockchain. To the best of our knowledge, this is the first systematic study for tokenization on blockchain

Using Blockchain to support Data & Service Monetization

Two required features of a data monetization platform are query and retrieval of the metadata of the resources to be monetized. Centralized platforms rely on the maturity of traditional NoSQL database systems to support these features. These databases, for example, MongoDB allows for very efficient query and retrieval of data it stores. However, centralized platforms come with a bag of security and privacy concerns, making them not the ideal approach for a data monetization platform. On the other hand, most existing decentralized platforms are only partially decentralized. In this research, I developed Cowry, a platform for publishing metadata describing available resources (data or services), discovery of published metadata including fast search and filtering. My main contribution is a fully decentralized architecture that combines blockchain and traditional distributed database to gain additional features such as efficient query and retrieval of metadata stored on the blockchain

Blockchain based architecture to increase trustability and transparency in manufacturing

As the fourth industrial revolution is now more of a reality than a mere futuristic vision, necessary changes need to be addressed in the manufacturing environment. The general inability of companies and customers to distinguish between truthful and untruthful information has opened a dangerous void; one that is often filled with fraud and greed. This, allied with the general population’s concerns over privacy and data mismanagement, has led to the birth of a new technology: blockchain. A universally accessible ledger that generates immutable data allows systems to be based on cryptography. Decentralized by nature, users no longer need to trust a centralized node with their data. The user becomes empowered as they are rewarded for participating, as opposed to a central entity reaping all of the wealth generated by the network. For companies in the manufacturing business, blockchain technology is also specially beneficial. Removing the trust factor among the actors in the horizontal integration of industry 4.0 translates to more transparency in the supply chain, which leads to a better overall vision and understanding of the product. The aim of this thesis is to implement an architecture connecting suppliers, retail and customers based on blockchain technology. Complete and reliable traceability of the product to the customer is the goal. By providing truthful information to all the actors involved in a product’s life cycle, value can be added, thus increasing transparency and trust in the whole network.À medida que a quarta revolução industrial se vai tornando cada vez mais presente, certas questões necessitam de ser repensadas. A incapacidade geral de empresas e do consumidor de distinguir informações verídicas de não verídicas abre um vazio que muitas vezes dá azo a ganância e fraude. A juntar a isto, uma acrescida preocupação da população geral em matérias como privacidade e uso indevido de dados levou a que uma nova tecnologia emergisse: blockchain. Uma lista universalmente acessível que gera dados imutáveis permite que sistemas tenham como base a criptografia. Descentralizada por natureza, os utilizadores deixam de ser forçados a confiar num nó central a sua informação. O utilizador ganha poder, passa a ser visto como um membro valioso e é recompensado por participar, ao invés de uma entidade central colher toda a riqueza gerada na rede. Para empresas no mundo da manufatura, a tecnologia de blockchain é especialmente atrativa. Remover a necessidade de confiança entre os atores na integração horizontal na indústria 4.0 traduz-se em maior transparência na supply chain, o que leva a uma melhor visão e compreensão do produto no geral. A finalidade desta tese é implementar uma arquitetura que conecta fornecedores, retail e consumidores baseada na tecnologia de blockchain. Rastreabilidade completa e fiável do produto é o objetivo. É possível acrescentar valor ao partilhar informação verídica a todos os atores envolvidos no ciclo de vida de um produto, o que leva a um aumento de transparência e confiança em toda a rede