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Advances in Blockchain Technology and Applications II
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Advances in Blockchain Technology and Applications II

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Computing and Artificial Intelligence".

Deadline for manuscript submissions: closed (31 May 2021) | Viewed by 61241

Special Issue Editors

Dr. Roberto Tonelli

E-Mail Website
Guest Editor
Department of Mathematics and Informatics, University of Cagliari, Cagliari, Italy
Interests: complex software systems; software engineering; blockchain and smart contracts
Special Issues, Collections and Topics in MDPI journals
Dr. Marco Ortu

E-Mail Website
Guest Editor
Department Electrical and Electronic Engineering, University of Cagliari, Cagliari, Italy
Interests: sentiment analysis; human factor; complex software systems; software engineering; blockchain and smart contracts
Dr. Andrea Pinna

E-Mail Website
Guest Editor
Department Electrical and Electronic Engineering, University of Cagliari, Cagliari, Italy
Interests: blockchain; smart contracts; software engineering; agile methodology; sustainable design
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The disrupting power of Blockchain technology is affecting and influencing our world, day by day. The number of researchers, software developers, and companies involved in this new technology is increasing exponentially, and this is also reflected in the number of projects that start every day, aimed at creating new blockchains, or new applications, built on existing blockchains. However, research papers devoted to the investigation of the various blockchains and the related programming languages used for coding in the Blockchain environment, though increasing, are still not enough. Therefore, we believe that initiatives aimed at inviting and putting together scientific works on this new technology should be encouraged. For this reason, we warmly welcome the proposal to edit a Special Issue of Applied Sciences on this subject.

The goal of the Special Issue is to gather sound scientific papers on the theoretical and practical aspects related to blockchain technologies and smart contracts. The main focus is on the application to blockchain and smart contract development of studies pertaining to the relevant main areas of computer science. Topics may include but are not limited to:

  • Blockchain and Dapp architectures;
  • Blockchain scaling and interplay;
  • Decentralized artificial intelligence;
  • Decentralized databases;
  • Static and dynamic blockchain analysis; blockchain forensics;
  • Big data and the blockchain;
  • Human–computer interaction for blockchain applications;
  • Blockchain and the Internet of things;
  • Languages for smart contract development;
  • Blockchain-oriented software engineering;
  • Blockchain security and testing;
  • Decentralized applications in supply chain management, industry, energy, logistic, gaming, etc.

Dr. Roberto Tonelli
Dr. Marco Ortu
Dr. Andrea Pinna
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Applied Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Blockchain
  • smart contracts
  • Dapps
  • distributed ledger technology
  • DLT
  • decentralized applications

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Published Papers (17 papers)

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Research

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15 pages, 484 KiB  
Article
Peer-to-Peer System Design Trade-Offs: A Framework Exploring the Balance between Blockchain and IPFS
by Ámbar Tenorio-Fornés, Samer Hassan and Juan Pavón
Appl. Sci. 2021, 11(21), 10012; https://doi.org/10.3390/app112110012 - 26 Oct 2021
Cited by 7 | Viewed by 2750
Abstract
The current state of the web, which is dominated by centralized cloud services, raises several concerns regarding different aspects such as governance, privacy, surveillance, and security. A way to address these issues is to decentralize the platforms by adopting new distributed technologies, such [...] Read more.
The current state of the web, which is dominated by centralized cloud services, raises several concerns regarding different aspects such as governance, privacy, surveillance, and security. A way to address these issues is to decentralize the platforms by adopting new distributed technologies, such as IPFS and Blockchain, which follow a full peer-to-peer model. This work proposes a set of guidelines to design decentralized systems, taking the different trade-offs these technologies face with regard to their consistency requirements into consideration. These guidelines are then illustrated with the design of a decentralized questions and answers system. This system serves to illustrate a framework to create decentralized services and applications that uses IPFS and Blockchain technologies and incorporates the discussion and guidelines of the paper, providing solutions for data access, data provenance, and data discovery. Thus, this work proposes a framework to assist in the design of new decentralized systems, proposing a set of guidelines to choose the appropriate technologies depending on the relevant requirements; e.g., considering if Blockchain technology may be required or IPFS might be sufficient. Full article
(This article belongs to the Special Issue Advances in Blockchain Technology and Applications II)
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17 pages, 27593 KiB  
Article
Lightweight Blockchain Processing. Case Study: Scanned Document Tracking on Tezos Blockchain
by Mohamed Allouche, Tarek Frikha, Mihai Mitrea, Gérard Memmi and Faten Chaabane
Appl. Sci. 2021, 11(15), 7169; https://doi.org/10.3390/app11157169 - 03 Aug 2021
Cited by 21 | Viewed by 2910
Abstract
To bridge the current gap between the Blockchain expectancies and their intensive computation constraints, the present paper advances a lightweight processing solution, based on a load-balancing architecture, compatible with the lightweight/embedding processing paradigms. In this way, the execution of complex operations is securely [...] Read more.
To bridge the current gap between the Blockchain expectancies and their intensive computation constraints, the present paper advances a lightweight processing solution, based on a load-balancing architecture, compatible with the lightweight/embedding processing paradigms. In this way, the execution of complex operations is securely delegated to an off-chain general-purpose computing machine while the intimate Blockchain operations are kept on-chain. The illustrations correspond to an on-chain Tezos configuration and to a multiprocessor ARM embedded platform (integrated into a Raspberry Pi). The performances are assessed in terms of security, execution time, and CPU consumption when achieving a visual document fingerprint task. It is thus demonstrated that the advanced solution makes it possible for a computing intensive application to be deployed under severely constrained computation and memory resources, as set by a Raspberry Pi 3. The experimental results show that up to nine Tezos nodes can be deployed on a single Raspberry Pi 3 and that the limitation is not derived from the memory but from the computation resources. The execution time with a limited number of fingerprints is 40% higher than using a classical PC solution (value computed with 95% relative error lower than 5%). Full article
(This article belongs to the Special Issue Advances in Blockchain Technology and Applications II)
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18 pages, 300 KiB  
Article
A Guidance for Blockchain-Based Digital Transition in Supply Chains
by Fabio Della Valle and Miquel Oliver
Appl. Sci. 2021, 11(14), 6523; https://doi.org/10.3390/app11146523 - 15 Jul 2021
Cited by 7 | Viewed by 2366
Abstract
Blockchains play a crucial role in the digitalization of future supply chains (SCs). In this study, we analyzed the major influences that blockchain-based digital business strategies may play in SC operations. We conducted 18 interviews with international experts from different sectors and analyzed [...] Read more.
Blockchains play a crucial role in the digitalization of future supply chains (SCs). In this study, we analyzed the major influences that blockchain-based digital business strategies may play in SC operations. We conducted 18 interviews with international experts from different sectors and analyzed the collected data using the grounded theory approach, identifying four major categories. A set of three matrices is presented to address those elements that may support digital transition procedures in SCs: (1) value of trust and automation, (2) transformative role for operations, and (3) digital business strategy identification. As an additional result, a reference framework was identified for the evaluation and detection of those aspects to be taken into consideration during blockchain adoption in SCs. For use as a guide, this result comprises 22 recommendations and was framed in four progressive steps as follows: (1) identify, (2) assess, (3) design, and (4) assure. Full article
(This article belongs to the Special Issue Advances in Blockchain Technology and Applications II)
11 pages, 1670 KiB  
Article
The Modification of pBFT Algorithm to Increase Network Operations Efficiency in Private Blockchains
by Youn-A Min
Appl. Sci. 2021, 11(14), 6313; https://doi.org/10.3390/app11146313 - 08 Jul 2021
Cited by 13 | Viewed by 2608
Abstract
The use of blockchain technology is becoming more widespread. Governments have expanded their use of the technology from online polls to business management of smaller local governments while private institutions have increased their services from financial to medical services management. This paper presents [...] Read more.
The use of blockchain technology is becoming more widespread. Governments have expanded their use of the technology from online polls to business management of smaller local governments while private institutions have increased their services from financial to medical services management. This paper presents the modified pBFT blockchain consensus algorithm for a more efficient data management method in cases of applying blockchains in authorized nodes such as governmental agencies. The network communication cost was minimized while the consensus accuracy was maximized by applying a method of simplifying the request management process and electing the reliability-based consensus node during the pBFT consensus algorithm process. By applying the modified pBFT consensus algorithm, stability and speed of the consensus and verification process among various organizations can be guaranteed as well as application in efficient management and value creation of data. Full article
(This article belongs to the Special Issue Advances in Blockchain Technology and Applications II)
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14 pages, 783 KiB  
Article
Towards a GDPR-Compliant Blockchain-Based COVID Vaccination Passport
by AKM Bahalul Haque, Bilal Naqvi, A. K. M. Najmul Islam and Sami Hyrynsalmi
Appl. Sci. 2021, 11(13), 6132; https://doi.org/10.3390/app11136132 - 01 Jul 2021
Cited by 24 | Viewed by 5330
Abstract
The COVID-19 pandemic has shaken the world and limited work/personal life activities. Besides the loss of human lives and agony faced by humankind, the pandemic has badly hit different sectors economically, including the travel industry. Special arrangements, including COVID test before departure and [...] Read more.
The COVID-19 pandemic has shaken the world and limited work/personal life activities. Besides the loss of human lives and agony faced by humankind, the pandemic has badly hit different sectors economically, including the travel industry. Special arrangements, including COVID test before departure and on arrival, and voluntary quarantine, were enforced to limit the risk of transmission. However, the hope for returning to a normal (pre-COVID) routine relies on the success of the current COVID vaccination drives administered by different countries. To open for tourism and other necessary travel, a need is realized for a universally accessible proof of COVID vaccination, allowing travelers to cross the borders without any hindrance. This paper presents an architectural framework for a GDPR-compliant blockchain-based COVID vaccination passport (VacciFi), whilst considering the relevant developments, especially in the European Union region. Full article
(This article belongs to the Special Issue Advances in Blockchain Technology and Applications II)
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24 pages, 2809 KiB  
Article
Application of Blockchain in Education: GDPR-Compliant and Scalable Certification and Verification of Academic Information
by Christian Delgado-von-Eitzen, Luis Anido-Rifón and Manuel J. Fernández-Iglesias
Appl. Sci. 2021, 11(10), 4537; https://doi.org/10.3390/app11104537 - 16 May 2021
Cited by 12 | Viewed by 4533
Abstract
Blockchain technologies are awakening in recent years the interest of different actors in various sectors and, among them, the education field, which is studying the application of these technologies to improve information traceability, accountability, and integrity, while guaranteeing its privacy, transparency, robustness, trustworthiness, [...] Read more.
Blockchain technologies are awakening in recent years the interest of different actors in various sectors and, among them, the education field, which is studying the application of these technologies to improve information traceability, accountability, and integrity, while guaranteeing its privacy, transparency, robustness, trustworthiness, and authenticity. Different interesting proposals and projects were launched and are currently being developed. Nevertheless, there are still issues not adequately addressed, such as scalability, privacy, and compliance with international regulations such as the General Data Protection Regulation in Europe. This paper analyzes the application of blockchain technologies and related challenges to issue and verify educational data and proposes an innovative solution to tackle them. The proposed model supports the issuance, storage, and verification of different types of academic information, both formal and informal, and complies with applicable regulations, protecting the privacy of users’ personal data. This proposal also addresses the scalability challenges and paves the way for a global academic certification system. Full article
(This article belongs to the Special Issue Advances in Blockchain Technology and Applications II)
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24 pages, 1750 KiB  
Article
PetroBlock: A Blockchain-Based Payment Mechanism for Fueling Smart Vehicles
by Faisal Jamil, Omar Cheikhrouhou, Harun Jamil, Anis Koubaa, Abdelouahid Derhab and Mohamed Amine Ferrag
Appl. Sci. 2021, 11(7), 3055; https://doi.org/10.3390/app11073055 - 29 Mar 2021
Cited by 34 | Viewed by 3804
Abstract
Current developments in information technology and increased inclination towards smart cities have led to the initiation of a plethora of features by technology-oriented companies (i.e., car manufacturers) to improve users’ privacy and comfort. The invention of smart vehicle technology paved the way for [...] Read more.
Current developments in information technology and increased inclination towards smart cities have led to the initiation of a plethora of features by technology-oriented companies (i.e., car manufacturers) to improve users’ privacy and comfort. The invention of smart vehicle technology paved the way for the excessive use of machine-to-machine technologies. Moreover, third-party sharing of financial services are also introduced that support machine-to-machine (M2M) communication. These monetary systems’ prime focus is on improving reliability and security; however, they overlook aspects like behaviors and users’ need. For instance, people often hand over their bank cards or share their credentials with their colleagues to withdraw money on their behalf. Such behaviors may originate issues about privacy and security that can have severe losses for the card owner. This paper presents a novel blockchain-based strategy for payment of fueling of smart cars without any human interaction while maintaining transparency, privacy, and trust. The proposed system is capable of data sharing among the users of the system while securing sensitive information. Moreover, we also provide a blockchain-based secure privacy-preserving strategy for payment of fueling among the fuel seller and buyer without human intervention. Furthermore, we have also analytically evaluated several experiments to determine the proposed blockchain platform’s usability and efficiency. Lastly, we harness Hyperledger Caliper to assess the proposed system’s performance in terms of transaction latency, transactions per second, and resource consumption. Full article
(This article belongs to the Special Issue Advances in Blockchain Technology and Applications II)
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18 pages, 1367 KiB  
Article
Mining Pool Selection under Block WithHolding Attack
by Kentaro Fujita, Yuanyu Zhang, Masahiro Sasabe and Shoji Kasahara
Appl. Sci. 2021, 11(4), 1617; https://doi.org/10.3390/app11041617 - 10 Feb 2021
Cited by 10 | Viewed by 3812
Abstract
In current Proof-of-Work (PoW) blockchain systems, miners usually form mining pools to compete with other pools/miners in the mining competition. Forming pools can give miners steady revenues but will introduce two critical issues. One is mining pool selection, where miners select the pools [...] Read more.
In current Proof-of-Work (PoW) blockchain systems, miners usually form mining pools to compete with other pools/miners in the mining competition. Forming pools can give miners steady revenues but will introduce two critical issues. One is mining pool selection, where miners select the pools to join in order to maximize their revenues. The other is a Block WithHolding (BWH) attack, where pools can inject part of their hash/mining power into other pools to obtain additional revenues without contributing to the mining process of the attacked pools. Reasoning that the BWH attack will have significant impacts on the pool selection, we therefore investigate the mining pool selection issue in the presence of a BWH attack in this paper. In particular, we model the pool selection process of miners as an evolutionary game and find the Evolutionarily Stable States (ESSs) of the game (i.e., stable pool population states) as the solutions. Previous studies investigated this problem from the perspective of pool managers and neglected the revenues from attacked pools (attacking revenues), leading to less accurate and insightful findings. This paper, however, focuses on the payoffs of miners and carefully takes the attacking revenues into consideration. To demonstrate how the problem is solved, we consider the scenario with two mining pools and further investigate the case where one pool attacks the other and the case where the two pools attack each other. The results in this paper show that pools can attract more miners to join by launching a BWH attack and the attack power significantly affects the stable pool populations. Full article
(This article belongs to the Special Issue Advances in Blockchain Technology and Applications II)
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20 pages, 3788 KiB  
Article
Blockchain-Based Distributed Patient-Centric Image Management System
by Mohamed Yaseen Jabarulla and Heung-No Lee
Appl. Sci. 2021, 11(1), 196; https://doi.org/10.3390/app11010196 - 28 Dec 2020
Cited by 38 | Viewed by 4648
Abstract
In recent years, many researchers have focused on developing a feasible solution for storing and exchanging medical images in the field of health care. Current practices are deployed on cloud-based centralized data centers, which increase maintenance costs, require massive storage space, and raise [...] Read more.
In recent years, many researchers have focused on developing a feasible solution for storing and exchanging medical images in the field of health care. Current practices are deployed on cloud-based centralized data centers, which increase maintenance costs, require massive storage space, and raise privacy concerns about sharing information over a network. Therefore, it is important to design a framework to enable sharing and storing of big medical data efficiently within a trustless environment. In the present paper, we propose a novel proof-of-concept design for a distributed patient-centric image management (PCIM) system that is aimed to ensure safety and control of patient private data without using a centralized infrastructure. In this system, we employed an emerging Ethereum blockchain and a distributed file system technology called Inter-Planetary File System (IPFS). Then, we implemented an Ethereum smart contract called the patient-centric access control protocol to enable a distributed and trustworthy access control policy. IPFS provides the means for decentralized storage of medical images with global accessibility. We describe how the PCIM system architecture facilitates the distributed and secured patient-centric data access across multiple entities such as hospitals, patients, and image requestors. Finally, we deployed a smart contract prototype on an Ethereum testnet blockchain and evaluated the proposed framework within the Windows environment. The evaluation results demonstrated that the proposed scheme is efficient and feasible. Full article
(This article belongs to the Special Issue Advances in Blockchain Technology and Applications II)
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25 pages, 16196 KiB  
Article
Block Data Record-Based Dynamic Encryption Key Generation Method for Security between Devices in Low Power Wireless Communication Environment of IoT
by Soohwan Cho, Deokyoon Ko and Sooyoung Park
Appl. Sci. 2020, 10(21), 7940; https://doi.org/10.3390/app10217940 - 09 Nov 2020
Cited by 1 | Viewed by 2351
Abstract
The Internet of Things uses low-power wireless communication for wireless connectivity and efficient energy. Low-power wireless communication is applied to IoT for wireless connection and efficient energy consumption in various areas such as wearable devices, smart homes, and power plants in order to [...] Read more.
The Internet of Things uses low-power wireless communication for wireless connectivity and efficient energy. Low-power wireless communication is applied to IoT for wireless connection and efficient energy consumption in various areas such as wearable devices, smart homes, and power plants in order to send and receive data and control the environment. Security is becoming more important because the Internet of Things controls real physical systems. For the security of the Internet of Things, the encryption key is important to identify and authenticate devices that are trusted. The static encryption key method used for devices is likely to be calculated in reverse through the value of the key and is vulnerable to exploitation attacks. This requires the application of dynamic encryption keys that generate keys periodically. However, in the case of low-power wireless communication, the asynchronous communication method and the packet loss make it difficult to apply existing dynamic encryption key technologies. In this paper, we proposed dynamic encryption key method that applies the mechanism of the block chain to solve these problems. Based on the history of sensor data between devices, encryption keys are dynamically generated. The proposed method is to generate the same encryption key between devices with only one step of asynchronous communication considering packet loss. The proposed method is also validated in terms of availability and security in the Internet of Things low-power wireless communication. Full article
(This article belongs to the Special Issue Advances in Blockchain Technology and Applications II)
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20 pages, 914 KiB  
Article
A Coordination Technique for Improving Scalability of Byzantine Fault-Tolerant Consensus
by Jungwon Seo, Deokyoon Ko, Suntae Kim and Sooyong Park
Appl. Sci. 2020, 10(21), 7609; https://doi.org/10.3390/app10217609 - 28 Oct 2020
Cited by 9 | Viewed by 2595
Abstract
Among various consensus algorithms, the Byzantine Fault Tolerance (BFT)-based consensus algorithms are broadly used for private blockchain. However, as BFT-based consensus algorithms are structured for all participants to take part in a consensus process, a scalability issue becomes more noticeable. In this approach, [...] Read more.
Among various consensus algorithms, the Byzantine Fault Tolerance (BFT)-based consensus algorithms are broadly used for private blockchain. However, as BFT-based consensus algorithms are structured for all participants to take part in a consensus process, a scalability issue becomes more noticeable. In this approach, we introduce a consensus coordinator to execute a conditionally BFT-based consensus algorithm by classifying transactions. Transactions are divided into equal and unequal transactions. Moreover, unequal transactions are divided again and classified as common and trouble transactions. After that, a consensus algorithm is only executed for trouble transactions, and BFT-based consensus algorithms can achieve scalability. For evaluating our approach, we carried out three experiments in response to three research questions. By applying our approach to PBFT, we obtained 4.75 times better performance than using only PBFT. In the other experiment, we applied our approach to IBFT of Hyperledger Besu, and our result shows a 61.81% performance improvement. In all experiments depending on the change of the number of blockchain nodes, we obtained the better performance than original BFT-based consensus algorithms; thus, we can conclude that our approach improved the scalability of original BFT-based consensus algorithms. We also showed a correlation between performance and trouble transactions associated with transaction issue intervals and the number of blockchain nodes. Full article
(This article belongs to the Special Issue Advances in Blockchain Technology and Applications II)
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22 pages, 2067 KiB  
Article
Practical I-Voting on Stellar Blockchain
by Stanisław Barański, Julian Szymański, Andrzej Sobecki, David Gil and Higinio Mora
Appl. Sci. 2020, 10(21), 7606; https://doi.org/10.3390/app10217606 - 28 Oct 2020
Cited by 11 | Viewed by 3854
Abstract
In this paper, we propose a privacy-preserving i-voting system based on the public Stellar Blockchain network. We argue that the proposed system satisfies all requirements stated for a robust i-voting system including transparency, verifiability, and voter anonymity. The practical architecture of the system [...] Read more.
In this paper, we propose a privacy-preserving i-voting system based on the public Stellar Blockchain network. We argue that the proposed system satisfies all requirements stated for a robust i-voting system including transparency, verifiability, and voter anonymity. The practical architecture of the system abstracts a voter from blockchain technology used underneath. To keep user privacy, we propose a privacy-first protocol that protects voter anonymity. Additionally, high throughput and low transaction fees allow handling large scale voting at low costs. As a result we built an open-source, cheap, and secure system for i-voting that uses public blockchain, where everyone can participate and verify the election process without the need to trust a central authority. The main contribution to the field is a method based on a blind signature used to construct reliable voting protocol. The proposed method fulfills all requirements defined for i-voting systems, which is challenging to achieve altogether. Full article
(This article belongs to the Special Issue Advances in Blockchain Technology and Applications II)
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22 pages, 781 KiB  
Article
From Agents to Blockchain: Stairway to Integration
by Giovanni Ciatto, Stefano Mariani, Andrea Omicini and Franco Zambonelli
Appl. Sci. 2020, 10(21), 7460; https://doi.org/10.3390/app10217460 - 23 Oct 2020
Cited by 4 | Viewed by 2418
Abstract
The blockchain concept and technology are impacting many different research and application fields; hence, many are looking at the blockchain as a chance to solve long-standing problems or gain novel benefits. In the agent community several authors are proposing their own combination of [...] Read more.
The blockchain concept and technology are impacting many different research and application fields; hence, many are looking at the blockchain as a chance to solve long-standing problems or gain novel benefits. In the agent community several authors are proposing their own combination of agent-oriented technology and blockchain to address both old and new challenges. In this paper we aim at clarifying which are the opportunities, the dimensions to consider, and the alternative approaches available for integrating agents and blockchain, by proposing a roadmap and illustrating the issues yet to be addressed. Then, as both validation of our roadmap and grounds for future development, we discuss the case of Tenderfone, a custom blockchain integrating concepts borrowed from agent-oriented programming. Full article
(This article belongs to the Special Issue Advances in Blockchain Technology and Applications II)
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23 pages, 1157 KiB  
Article
Proof of Adjourn (PoAj): A Novel Approach to Mitigate Blockchain Attacks
by Sarwar Sayeed and Hector Marco-Gisbert
Appl. Sci. 2020, 10(18), 6607; https://doi.org/10.3390/app10186607 - 22 Sep 2020
Cited by 17 | Viewed by 4329
Abstract
The blockchain is a distributed ledger technology that is growing in importance since inception. Besides cryptocurrencies, it has also crossed its boundary inspiring various organizations, enterprises, or business establishments to adopt this technology benefiting from the most innovative security features. The decentralized and [...] Read more.
The blockchain is a distributed ledger technology that is growing in importance since inception. Besides cryptocurrencies, it has also crossed its boundary inspiring various organizations, enterprises, or business establishments to adopt this technology benefiting from the most innovative security features. The decentralized and immutable aspects have been the key points that endorse blockchain as one of the most secure technologies at the present time. However, in recent times such features seemed to be faded due to new attacking techniques. One of the biggest challenges remains within the consensus protocol itself, which is an essential component to bring all network participants to an agreed state. Cryptocurrencies adopt suitable consensus protocols based on their mining requirement, and Proof of Work (PoW) is the consensus protocol that is being predominated in major cryptocurrencies. Recent consensus protocol-based attacks, such as the 51% attack, Selfish Mining, Miner Bribe Attack, Zero Confirmation Attack, and One Confirmation Attack have been demonstrated feasible. To overcome these attacks, we propose Proof of Adjourn (PoAj), a novel consensus protocol that provides strong protection regardless of attackers hashing capability. After analyzing the 5 major attacks, and current protection techniques indicating the causes of their failure, we compared the PoAj against the most widely used PoW, showing that PoAj is not only able to mitigate the 5 attacks but also attacks relying on having a large amount of hashing power. In addition, the proposed PoAj showed to be an effective approach to mitigate the processing time issue of large-sized transactions. PoAj is not tailored to any particular attack; therefore, it is effective against malicious powerful players. The proposed approach provides a strong barrier not only to current and known attacks but also to future unknown attacks based on different strategies that rely on controlling the majority of the hashing power. Full article
(This article belongs to the Special Issue Advances in Blockchain Technology and Applications II)
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14 pages, 913 KiB  
Article
Rentable CDN Using Blockchain and Proof of Provenance
by Suah Kim, Vasily Sachnev and Hyoung Joong Kim
Appl. Sci. 2020, 10(18), 6570; https://doi.org/10.3390/app10186570 - 20 Sep 2020
Viewed by 1995
Abstract
Building a rentable content delivery network (CDN), a p2p based CDN that supports content control and is composed of hardware rented from consumers, requires significant trust between the renters and consumers. The proposed method solves this using a Blockchain to provide transparency in [...] Read more.
Building a rentable content delivery network (CDN), a p2p based CDN that supports content control and is composed of hardware rented from consumers, requires significant trust between the renters and consumers. The proposed method solves this using a Blockchain to provide transparency in running the network, and proof of provenance, a verifiable proof origin of the content that is used to determine who can get paid for their services to discourage malicious activities. Full article
(This article belongs to the Special Issue Advances in Blockchain Technology and Applications II)
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19 pages, 3103 KiB  
Article
Easing ĐApp Interaction for Non-Blockchain Users from a Conceptual Modelling Approach
by Miguel A. Teruel and Juan Trujillo
Appl. Sci. 2020, 10(12), 4280; https://doi.org/10.3390/app10124280 - 22 Jun 2020
Cited by 5 | Viewed by 3685
Abstract
Blockchain decentralized applications (ÐApp’s) are applications which run on blockchains nodes. Thus, to interact directly with this sort of applications, users need to have a blockchain address, wallet, and knowledge about how to make transactions to interact with ÐApp’s. Therefore, the knowledge required [...] Read more.
Blockchain decentralized applications (ÐApp’s) are applications which run on blockchains nodes. Thus, to interact directly with this sort of applications, users need to have a blockchain address, wallet, and knowledge about how to make transactions to interact with ÐApp’s. Therefore, the knowledge required to use a ÐApp can easily make users to desist when trying to interact with them. To tackle this issue, we propose a software architecture that will be in the middle of the user and the ÐApp, thus making users initially unaware of the fact that they are interacting with a ÐApp. This is achieved by analyzing the relationship between ÐApps and Apps by using UML modelling. Next, based on the previous analysis, we created a middleware for users to interact with a ÐApp in the same manner they do with a traditional web app, i.e., by using usernames, passwords and user interface elements instead of addresses, private keys or transactions. To put the developed middleware into practice, we developed a ÐApp that makes use of it. This ÐApp registers the time control of workers from companies by using blockchain to store the data in a secure and non-modifiable manner. Finally, we performed an experiment, thus demonstrating that a ÐApp that implements the proposed middleware would improve its usability for users with no experience with blockchain. Full article
(This article belongs to the Special Issue Advances in Blockchain Technology and Applications II)
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Review

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27 pages, 891 KiB  
Review
A Cross-Sectional Review of Blockchain in Thailand: Research Literature, Education Courses, and Industry Projects
by Suporn Pongnumkul, Thachaparn Bunditlurdruk, Pimwadee Chaovalit and Atima Tharatipyakul
Appl. Sci. 2021, 11(11), 4928; https://doi.org/10.3390/app11114928 - 27 May 2021
Cited by 7 | Viewed by 3565
Abstract
Blockchain technology, a decentralized database that encourages collaboration, transparency, and security, is popular in Thailand, as seen from many practical projects. Nevertheless, information about Thailand’s blockchain ecosystem is incomplete. We conducted literature reviews of research articles, education courses, and industry projects, to explore [...] Read more.
Blockchain technology, a decentralized database that encourages collaboration, transparency, and security, is popular in Thailand, as seen from many practical projects. Nevertheless, information about Thailand’s blockchain ecosystem is incomplete. We conducted literature reviews of research articles, education courses, and industry projects, to explore blockchain from the technology adoption flow including academic research, knowledge acquisition, and project implementation. Blockchain research articles were collected from the Scopus database, while projects and courses were retrieved from an internet search. After applying inclusion and exclusion criteria, a total of 13 research articles, 50 courses, and 54 industry projects, dated from 2016 to 2020, were included in our review. Based on an analysis with respect to trends, focuses, and characteristics in all three aspects, we found that blockchain technology in Thailand was in its infancy, but has been increasing in numbers and domain varieties. However, blockchain technology did not move towards the same direction for all aspects. Most research articles were found in government services, supply chain, and traceability domains; while most projects were in the financial domains. We offer possible explanations for this observation. This paper provides challenges and opportunities for the research community and involved parties in practical implementation. Full article
(This article belongs to the Special Issue Advances in Blockchain Technology and Applications II)
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