Analysis of Blockchain consensus mechanisms : Proof-of-Work vs Proof-of-Stake

The objective of this thesis is to understand and evaluate the two popular consensus mechanisms of blockchain: Proof-of-Work (PoW) and Proof-of-Stake (PoS), especially in terms of their cost effectiveness. This study attempts to answer one significant research question: “Researchers assume that blockchain cannot takeover computer networks, as it requires excessive computation power. If blockchain moved to a Proof-of-Stake (PoS) consensus algorithm would takeovers remain equally difficult?” The thesis uses qualitative desk research approach by utilizing the existing research papers and published reports related to the topic. It attempts to draw comparison between both consensus algorithms and extracts reasonable conclusions based on the simulation experiment results. The three main comparison points discussed among the consensus protocols are energy consumption, decentralization, and security of blockchain. This study concludes that Proof-of-Stake (PoS) consumes less energy than the Proof-of-Work (PoW) and also shows better results in providing decentralization and security as compared to Proof-of-Work (PoW). Hence, takeovers are easier with PoS over PoW, but PoS still has room for improvement to reduce the required energy resources and further research studies are needed to analyse it

Towards Security and Privacy in Networked Medical Devices and Electronic Healthcare Systems

E-health is a growing eld which utilizes wireless sensor networks to enable access to effective and efficient healthcare services and provide patient monitoring to enable early detection and treatment of health conditions. Due to the proliferation of e-health systems, security and privacy have become critical issues in preventing data falsification, unauthorized access to the system, or eavesdropping on sensitive health data. Furthermore, due to the intrinsic limitations of many wireless medical devices, including low power and limited computational resources, security and device performance can be difficult to balance. Therefore, many current networked medical devices operate without basic security services such as authentication, authorization, and encryption. In this work, we survey recent work on e-health security, including biometric approaches, proximity-based approaches, key management techniques, audit mechanisms, anomaly detection, external device methods, and lightweight encryption and key management protocols. We also survey the state-of-the art in e-health privacy, including techniques such as obfuscation, secret sharing, distributed data mining, authentication, access control, blockchain, anonymization, and cryptography. We then propose a comprehensive system model for e-health applications with consideration of battery capacity and computational ability of medical devices. A case study is presented to show that the proposed system model can support heterogeneous medical devices with varying power and resource constraints. The case study demonstrates that it is possible to signicantly reduce the overhead for security on power-constrained devices based on the proposed system model

Advances in Information Security and Privacy

With the recent pandemic emergency, many people are spending their days in smart working and have increased their use of digital resources for both work and entertainment. The result is that the amount of digital information handled online is dramatically increased, and we can observe a significant increase in the number of attacks, breaches, and hacks. This Special Issue aims to establish the state of the art in protecting information by mitigating information risks. This objective is reached by presenting both surveys on specific topics and original approaches and solutions to specific problems. In total, 16 papers have been published in this Special Issue

A proposal for the use of blockchain in the portuguese voting system

Dissertation presented as the partial requirement for obtaining a Master's degree in Information Management, specialization in Knowledge Management and Business IntelligenceThe key objective of this proposal is to present one of the problems that the Portuguese economy, as well as other European countries, have been facing in regard to the civil society intervention in the democracy: the decrease of turnover rates in the voting system. The main objective is to propose the use of Blockchain technology in the Portuguese Voting System, as a mechanism to counter this trend. In order to understand how the possible application of a remote e-voting system succeeds, Estonia was selected as the case of study. Its architecture, as well as the legal, social and technological issues and challenges associated are investigated in the light of the information collected in the literature review. Considering the case analysis and discussion, a set of recommendations that purpose the use of a remote electronic voting system in the Portuguese electoral system are presented and a critical analysis about the introduction of a Blockchain algorithm is made. This dissertation concludes about the advantages and disadvantages from the use of this decentralized system when compared with a system involving a third-party as the one used in the Estonian I-Voting. The validation is based on interviews and discussions with professors in the area of information systems and law, and also with a contribution of a Digital adviser of the Estonian e-Governance model

Introducing the new paradigm of Social Dispersed Computing: Applications, Technologies and Challenges

[EN] If last decade viewed computational services as a utility then surely this decade has transformed computation into a commodity. Computation is now progressively integrated into the physical networks in a seamless way that enables cyber-physical systems (CPS) and the Internet of Things (IoT) meet their latency requirements. Similar to the concept of ¿platform as a service¿ or ¿software as a service¿, both cloudlets and fog computing have found their own use cases. Edge devices (that we call end or user devices for disambiguation) play the role of personal computers, dedicated to a user and to a set of correlated applications. In this new scenario, the boundaries between the network node, the sensor, and the actuator are blurring, driven primarily by the computation power of IoT nodes like single board computers and the smartphones. The bigger data generated in this type of networks needs clever, scalable, and possibly decentralized computing solutions that can scale independently as required. Any node can be seen as part of a graph, with the capacity to serve as a computing or network router node, or both. Complex applications can possibly be distributed over this graph or network of nodes to improve the overall performance like the amount of data processed over time. In this paper, we identify this new computing paradigm that we call Social Dispersed Computing, analyzing key themes in it that includes a new outlook on its relation to agent based applications. We architect this new paradigm by providing supportive application examples that include next generation electrical energy distribution networks, next generation mobility services for transportation, and applications for distributed analysis and identification of non-recurring traffic congestion in cities. The paper analyzes the existing computing paradigms (e.g., cloud, fog, edge, mobile edge, social, etc.), solving the ambiguity of their definitions; and analyzes and discusses the relevant foundational software technologies, the remaining challenges, and research opportunities.Garcia Valls, MS.; Dubey, A.; Botti, V. (2018). Introducing the new paradigm of Social Dispersed Computing: Applications, Technologies and Challenges. Journal of Systems Architecture. 91:83-102. https://doi.org/10.1016/j.sysarc.2018.05.007S831029

Ghostor: Toward a Secure Data-Sharing System from Decentralized Trust

Data-sharing systems are often used to store sensitive data. Both academia and industry have proposed numerous solutions to protect user privacy and data integrity from a compromised server. Practical state-of-the-art solutions, however, use weak threat models based on centralized trust—they assume that part of the server will remain uncompromised, or that the adversary will not perform active attacks. We propose Ghostor, a data-sharing system that, using only decentralized trust, (1) hides user identities from the server, and (2) allows users to detect server-side integrity violations. To achieve (1), Ghostor avoids keeping any per-user state at the server, requiring us to redesign the system to avoid common paradigms like per-user authentication and user-specific mailboxes. To achieve (2), Ghostor develops a technique called verifiable anonymous history. Ghostor leverages a blockchain rarely, publishing only a single hash to the blockchain for the entire system once every epoch. We measured that Ghostor incurs a 4–5x throughput overhead compared to an insecure baseline. Although significant, Ghostor\u27s overhead may be worth it for security- and privacy-sensitive applications

The State of the Electronic Identity Market: Technologies, Infrastructure, Services and Policies

Authenticating onto systems, connecting to mobile networks and providing identity data to access services is common ground for most EU citizens, however what is disruptive is that digital technologies fundamentally alter and upset the ways identity is managed, by people, companies and governments. Technological progress in cryptography, identity systems design, smart card design and mobile phone authentication have been developed as a convenient and reliable answer to the need for authentication. Yet, these advances ar enot sufficient to satisfy the needs across people's many spheres of activity: work, leisure, health, social activities nor have they been used to enable cross-border service implementation in the Single Digital Market, or to ensure trust in cross border eCommerce. The study findings assert that the potentially great added value of eID technologies in enabling the Digital Economy has not yet been fulfilled, and fresh efforts are needed to build identification and authentication systems that people can live with, trust and use. The study finds that usability, minimum disclosure and portability, essential features of future systems, are at the margin of the market and cross-country, cross-sector eID systems for business and public service are only in their infancy. This report joins up the dots, and provides significant exploratory evidence of the potential of eID for the Single Digital Market. A clear understanding of this market is crucial for policy action on identification and authentication, eSignature and interoperability.JRC.DDG.J.4-Information Societ