Special issue | Blockchain Networks and Distributed Protocols

Vol. 77, n° 1-2, January-February 2022
Content available on Springerlink

Guest editors

Maria Potop‑Butucaru, Sorbonne University, Paris, France
Ariel Orda, Technion, Haifa, Israel
Maurice Herlihy, Brown University, Providence, USA
Stefano Secci, Cnam, Paris, France


Special issue on blockchain networks and distributed protocols

Maria Potop‑Butucaru · Ariel Orda · Maurice Herlihy · Stefano Secci

Realizing privacy aspects in blockchain networks

Oded Noam1, Ori Rottenstreich2
(1) Orbs, Tel Aviv, Israel
(2) Technion – Israel Institute of Technology, Haifa, Israel

Abstract The right to personal privacy is known as a fundamental human right allowing people to restrict access to their personal information. The decentralized nature of blockchain networks, often involving the publicity of ledger information, can come into conflict with this right. This is in particular the case when the blockchain maintains sensitive information such as financial credits or medical information. In this paper, we discuss this interaction. We first describe multiple aspects of privacy such as its practical limit towards authorities, its potential vulnerability, and its association with technological systems such as blockchain networks. Towards answering these challenges, we survey a wide range of techniques relying on tools from the areas of cryptography, distributed system, and hardware architecture. We explain how each can be used to enhance privacy in blockchain networks following their unique nature. We further conclude that none of the available techniques can fully answer the complex practical requirements, and that practical solutions should combine both centrally controlled and decentralized systems.

Keywords  Blockchain · Privacy

Integration of blockchain and Internet of Things: challenges and solutions

S. Zafar1, K. M. Bhatti1, M. Shabbir1, F. Hashmat2, A. H. Akbar2
(1) Department of Electrical Engineering, National University of Computer and Emerging Sciences, Lahore campus, Lahore, Pakistan
(2) Department of Computer Engineering, University of Engineering and Technology, Lahore, Pakistan

Abstract Blockchain-based Internet of Things (BIoT) is an emerging paradigm of Internet of Things (IoT) which utilizes the blockchain technology to provide security services to the IoT applications. In essence, the blockchain built-in security mechanism can provide services such as availability, authentication, authorization, confidentiality, and integrity to the IoT applications. While most of the IoT devices are inherently resource-constrained in terms of computational power and storage capacity, the downside for blockchain is a requirement of massive amount of energy and computational resources for its operation, which poses challenges to the realization of BIoT. This paper strives to explore the challenges associated with the integration of blockchain and IoT and review their solutions. First, a brief introduction of blockchain technology is presented, followed by characterization of blockchain-based IoT applications as per their heterogeneous traffic demand and Quality of Service (QoS) requirements. Next, challenges that limit the design, development, and deployment of BIoT applications are explained in detail such as energy efficiency, privacy, throughput, latency, fork problem, security, legal issues, smart contracts, storage, and network broadcast mechanism and their proposed solutions are discussed. Finally, future research directions of blockchain and IoT integration are indicated. This investigation will benefit the researchers and developers to identify and solve blockchain and IoT integration challenges in order to realize efficient BIoT applications.

Keywords  Blockchain · Blockchain-Internet of Things integration · Internet of Things · Resource-constrained devices

eHealthChain—a blockchain‑based personal health information
management system

Pravin Pawar1, Neeraj Parolia2, Sameer Shinde3, Thierry Oscar Edoh4, Madhusudan Singh5
(1) Department of Computer Science, State University of  New York, Korea, Incheon, South Korea
(2) Department of Business Analytics and Technology Management, Towson University, Baltimore, MD, USA
(3) Softlabs Technologies and Developments Pvt. Ltd., Mumbai, India
(4) Chair for Applied Software Engineering, Technical University of Munich, Munich, Germany
(5) Department of Technology Studies, Endicott College of International Studies, Daejeon, South Korea

Abstract Medical IoT devices that use miniature sensors to collect patient’s bio-signals and connected medical applications are playing a crucial role in providing pervasive and personalized healthcare. This technological improvement has also created opportunities for the better management of personal health information. The Personal Health Information Management System (PHIMS) supports activities such as acquisition, storage, organization, integration, and privacy-sensitive retrieval of consumer’s health information. For usability and wide acceptance, the PHIMS should follow the design principles that guarantee privacy-aware health information sharing, individual information control, integration of information obtained from multiple medical IoT devices, health information security, and flexibility. Recently, blockchain technology has emerged as a lucrative option for the management of personal health information. In this paper, we propose eHealthChain—a blockchain-based PHIMS for managing health data originating from medical IoT devices and connected applications. The eHealthChain architecture consists of four layers, which are a blockchain layer for hosting a blockchain database, an IoT device layer for obtaining personal health data, an application layer for facilitating health data sharing, and an adapter layer, which interfaces the blockchain layer with an application layer. Compared to existing systems, eHealthChain provides complete control to the user in terms of personal health data acquisition, sharing, and self-management. We also present a detailed implementation of a Proof of Concept (PoC) prototype of eHealthChain system built using Hyperledger Fabric platform.

Keywords  Blockchain technology · Hyperledger Fabric · Personal health information management systems · IoT integration
· Adapter design pattern

BALAdIN: truthfulness in collaborative access networks with distributed ledgers

Vincent Messié1,2 · Gäel Fromentoux1, Nathalie Labidurie1, Benoit Radier1, Sandrine Vaton2, Isabel Amigo2
(1) Orange Labs, 2 Avenue Pierre Marzin, Lannion, France
(2) IMT Atlantique, 655 Avenue du Technopole, Plouzané, France

Abstract Distributed ledger technology (DLT), also known as “Blockchain” is one of the trendiest digital innovations in our era. While firstly applied to crypto-currencies, the trustworthiness inherent to DLT paved the way to many new usages notably in sectors such as land registration or banking where confidence in transactions is crucial. In the telecommunications sector, DLTs have enabled the development of future network architectures, such as new decentralised and multi-actor access networks. Having identified this as a great opportunity, we designed BALAdIN, a novel Blockchain-powered decentralised application that improves network coverage thanks to partnerships. Indeed, it allows a crowd of local actors such as shop tenants to deploy mobile cells with the help of a consortium of telcos. The traffic conveyed by each actor is traced thanks to a decentralised and trustworthy network monitoring mechanism we have designed. This mechanism both solves the centralisation dilemma caused by Blockchain Oracles and allows each actor to be rewarded depending on usage. In this paper, we focus on the description of this network usage monitoring mechanism. We then study the feasibility of its implementation onto regular Blockchain by studying its performance regarding the throughput and the propagation of the resulting Blockchain transactions. Finally, we derive a scalable deployment scheme for our novel Blockchain-powered decentralised network metering application BALAdIN.

Keywords  Blockchain · Distributed ledger technology · DApp · Collaborative network · Last mile network

Scalable blockchain execution via parallel block validation

Maya Leshkowitz1, Olivia Benattasse2, Oded Wertheim3, Ori Rottenstreich2
(1) Hebrew University, Jerusalem, Israel
(2) Technion, Haifa, Israel
(3) Orbs, Aviv-Yafo, Israel

Abstract A dominant part in blockchain networks is reaching an agreement on block transactions and their impact on the network state. We follow a common scenario where a node is selected to propose a block and its implied state updates. The proposal is then validated by other nodes that examine the block impact on the state. Typically, all validators execute the complete block and provide an indication based on comparing the results of their execution to the updated state in the proposal. With the increase in the number of participants in blockchain networks, we suggest a time-efficient block validation through splitting it into multiple disjoint tasks. This can be challenging due to possible dependencies between the block transactions. We describe the additional information the leader has to provide to enable that. Moreover, we describe a unique proof for the block partition computed by the leader such that when validated in part by the different committees guarantees the correctness of the execution by the leader. We compare the approach to traditional solutions based on real data of the Ethereum blockchain.

Keywords  Blockchain · Scalability · Transaction execution

Voting-based probabilistic consensuses and their applications in distributed ledgers

Serguei Popov1,2, Sebastian Müller2,3
(1) Centro de Matemática, University of Porto, Porto, Portugal
(2) IOTA Foundation, 10405 Berlin, Germany
(3) Aix Marseille Université, CNRS, Centrale Marseille, I2M-UMR 7373, Marseille, France

Abstract We review probabilistic models known as majority dynamics (also known as threshold voter models) and discuss their possible applications for achieving consensus in cryptocurrency systems. In particular, we show that using this approach in a straightforward way for practical consensus in a Byzantine setting can be problematic and requires extensive further research. We then discuss the Fast Probabilistic Consensus (FPC) protocol (Popov and Buchanan, J Parallel Distrib Comput 147:77–86, 2021), which circumvents the problems mentioned above by using external randomness.

Keywords  Distributed ledgers · Majority dynamics · Metastability · External Randomness · Fast probabilistic consensus (FPC)

Blockchain-based whistleblowing service to solve the problem of journalistic conflict of interest

Antonio Emerson B. Tomaz1, José Cláudio do Nascimento2, José Neuman de Souza3
(1) Federal University of Ceará, Campus of Crateús, Crateús, Brazil
(2) Federal University of Ceará, Campus of Sobral, Sobral, Brazil
(3) Federal University of Ceará, Campus of Pici, Fortaleza, Brazil

Abstract Whistleblowing through newspapers is common. However, the whistleblower may face some problems if the anonymous whistleblowing channel, usually maintained by journalistic organizations, is not reliable. The first problem is the conflict of interest when the whistleblowing involves commercial or political partners of the journalistic organization. The second problem is that, in conflict situations, the whistleblower’s anonymity can be unduly violated. To resolve these issues, we present a blockchain-based anonymous whistleblowing service. Our approach includes a cryptographic scheme based on a ring signature to ensure the whistleblower’s anonymity and, at the same time, give him/her the possibility to prove that he/she is the author of the whistleblowing in the future. Through game theory, we model two scenarios involving anonymous whistleblowing: the first is unfavorable to the whistleblower, and the second is quite favorable. We show that the whistleblowing channel proposed here, exploring blockchain’s properties and the reliability of ring signatures, creates favorable conditions for the whistleblower to feel motivated to disclose the whistleblowing.

Keywords  Blockchain · Conflict of interest · Whistleblowing · Ring signature · Anonymity · Game theory