Consortium blockchain management with a peer reputation system for critical information sharing

Blockchain technology based applications are emerging to establish distributed trust amongst organizations who want to share critical information for mutual benefit amongst their peers. There is a growing need for consortium based blockchain schemes that avoid issues such as false reporting and free riding that impact cooperative behavior between multiple domains/entities. Specifically, customizable mechanisms need to be developed to setup and manage consortiums with economic models and cloud-based data storage schemes to suit various application requirements. In this MS Thesis, we address the above issues by proposing a novel consortium blockchain architecture and related protocols that allow critical information sharing using a reputation system that manages co-operation amongst peers using off-chain cloud data storage and on-chain transaction records. We show the effectiveness of our consortium blockchain management approach for two use cases: (i) threat information sharing for cyber defense collaboration system viz., DefenseChain, and (ii) protected data sharing in healthcare information system viz., HonestChain. DefenseChain features a consortium Blockchain architecture to obtain threat data and select suitable peers to help with cyber attack (e.g., DDoS, Advance Persistent Threat, Cryptojacking) detection and mitigation. As part of DefenseChain, we propose a novel economic model for creation and sustenance of the consortium with peers through a reputation estimation scheme that uses 'Quality of Detection' and 'Quality of Mitigation' metrics. Similarly, HonestChain features a consortium Blockchain architecture to allow protected data sharing between multiple domains/entities (e.g., health data service providers, hospitals and research labs) with incentives and in a standards-compliant manner (e.g., HIPAA, common data model) to enable predictive healthcare analytics. Using an OpenCloud testbed with configurations with Hyperledger Composer as well as a simulation setup, our evaluation experiments for DefenseChain and HonestChain show that our reputation system outperforms state-of-the-art solutions and our consortium blockchain approach is highly scalableIncludes bibliographical references (pages 45-52)

Systematizing Decentralization and Privacy: Lessons from 15 Years of Research and Deployments

Decentralized systems are a subset of distributed systems where multiple authorities control different components and no authority is fully trusted by all. This implies that any component in a decentralized system is potentially adversarial. We revise fifteen years of research on decentralization and privacy, and provide an overview of key systems, as well as key insights for designers of future systems. We show that decentralized designs can enhance privacy, integrity, and availability but also require careful trade-offs in terms of system complexity, properties provided, and degree of decentralization. These trade-offs need to be understood and navigated by designers. We argue that a combination of insights from cryptography, distributed systems, and mechanism design, aligned with the development of adequate incentives, are necessary to build scalable and successful privacy-preserving decentralized systems