• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.249-251
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• 2021

PBFT (Practical Byzantine Fault Tolerant) is a consensus algorithm that guarantees higher processing speed compared to PoW (Proof of Work) and absolute finality that records are not overturned due to the superiority of computing power. However, due to the complexity of the message, there is a limit that the network load increases exponentially as the number of participating nodes increases. PBFT is an important factor in determining the performance of a blockchain network, but studies on evaluation metrics and evaluation technologies are lacking. In this paper, we propose a PBFT evaluation framework that is convenient to change the consensus algorithm to easily evaluate quantitative indicators and improved methods for evaluating PBFT.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.2
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• pp.271-277
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• 2022

PBFT (Practical Byzantine Fault Tolerant) is a consensus algorithm that can achieve consensus by resolving unintentional and intentional faults in a distributed network environment and can guarantee high performance and absolute finality. However, as the size of the network increases, the network load also increases due to message broadcasting that repeatedly occurs during the consensus process. Due to the characteristics of the PBFT algorithm, it is suitable for small/private blockchain, but there is a limit to its application to large/public blockchain. Because PBFT affects the performance of blockchain networks, the industry should test whether PBFT is suitable for products and services, and academia needs a unified evaluation metric and technology for PBFT performance improvement research. In this paper, quantitative evaluation metrics and evaluation frameworks that can evaluate PBFT family consensus algorithms are studied. In addition, the throughput, latency, and fault tolerance of PBFT are evaluated using the proposed PBFT evaluation framework.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.7
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• pp.3351-3368
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• 2019

The Internet of Things (IoT) enables machines and devices in a global network to connect and provide applications. The Vehicular Ad-hoc NETwork (VANET) allows vehicles in the network to communicate with each other as an application of the IoT. The safety and comfort of passengers can be improved through VANET related applications. In order to be able to provide related applications, there must be a reliable VANET topology. As a result of the Byzantine agreement (BA), fault tolerance can be solved in VANET. In order to improve the reliability of the system, even if some components in the system are damaged, a protocol is needed to assist the system to perform normally. Therefore, the BA problem in VANET with multiple impairments is revisited in this research. The proposed protocol allows all normal processing elements (PEs) to reach agreement using the least amount of information exchange. Moreover, the proposed protocol can tolerate the largest number of damaged PEs in VANET.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.5
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• pp.487-491
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• 2008

This paper proposes the Byzantine fault tolerant clock synchronization scheme for wireless sensor networks to cope with the clock synchronization disturbance attack of malicious nodes. In the proposed scheme, a node which is requiring clock synchronization receives 3m+1 clock synchronization messages not only from its parent nodes but also from its sibling nodes in order to tolerate malicious attacks even if up to m malicious nodes exist among them. The results show that the proposed scheme is 7 times more resilient to the clock synchronization disturbance attack of malicious nodes than existing schemes in terms of synchronization accuracy.

• Convergence Security Journal
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• v.20 no.3
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• pp.71-78
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• 2020

Bitcoin-based blockchain technology provides an infrastructure that enables anonymous smart contracts, low-cost remittances, and online payments. However, the block-chain technology that implements the bitcoin has scalability constraints in tradeoffs between throughput and latency. To solve these problems, the Byzantine fault tolerant block-chain technique has been proposed. This technique improves throughput without increasing latency by selecting a leader and constructing many microblocks that do not contain proofs of work within the existing block by the leader. However, this technique may be less secure than existing techniques in selecting the reader.

• Journal of Internet Computing and Services
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• v.21 no.1
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• pp.17-31
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• 2020

With the rapid development of block chain technology, attempts have been made to put the block chain technology into practical use in various fields such as finance and logistics, and also in the public sector where data integrity is very important. Defense Operations In addition, strengthening security and ensuring complete integrity of the command communication network is crucial for operational operation under the network-centered operational environment (NCOE). For this purpose, it is necessary to construct a command communication network applying the block chain network. However, the block chain technology up to now can not solve the security issues such as the 51% attack. In particular, the Practical Byzantine fault tolerance (PBFT) algorithm which is now widely used in blockchain, does not have a penalty factor for nodes that behave maliciously, and there is a problem of failure to make a consensus even if malicious nodes are more than 33% of all nodes. In this paper, we propose a Adaptive Consensus Bound PBFT (ACB-PBFT) algorithm that incorporates a penalty mechanism for anomalous behavior by combining the Trust model to improve the security of the PBFT, which is the main agreement algorithm of the blockchain.

• Proceedings of the Korea Information Processing Society Conference
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• 2019.05a
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• pp.197-200
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• 2019

가상 화폐 분야의 핵심 기술로 소개된 블록체인(Blockcahin) 기술은 4차 산업혁명에서 중심이 되는 기술로 주목받고 있다. 본 논문에서는 블록체인 시스템의 구조도와 대표적인 합의 알고리즘, 즉 증명(PoW: Proof of Work), 지분증명(PoS: Proof of Stake) 그리고 PBFT (Practical Byzantine Fault Tolerance)을 조사하였다. 합의 알고리즘의 특성을 분석하기 위하여, 보안성, 에너지 소비량, 거래 처리속도를 지표로 세워서 합의 알고리즘들에 대하여 전체적으로 비교 및 분석을 하였다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.4
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• pp.987-997
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• 2018

Blockchain has tamper-free, so many applications are developing to leverage tamper-free features of blockchain. MIT Media Labs proposed BlockCerts, educational certificate blockchain System, to solve problems of legacy certificate verifications. Existing educational certificate blockchain Systems are based on public blockchain such as bitcoin, Ethereum, so any entity can participate educational institute in principal. Moreover, the exisitng educational certricate blockchain system utilizes the integrity of blockchain, but the confidentiality of the educational certificate is not provided. This paper propose a digital certificate system based on private blockchain, name HyperCerts. Therefore, only trusted entity can participate in the private blockchain network, Hyperledger, as the issuer of digital certificate. Furthermore, the practical byzantine fault tolerance is used as consensus algorithm, HyperCerts reduce dramatically the latency of issuing digital certificate and required computing power. HyperCerts stores the hash value of digital certificate into the ledger, so breach of personal information by malicious entity in the private blockchain is protected.

• Journal of Korea Society of Digital Industry and Information Management
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• v.19 no.3
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• pp.37-44
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• 2023

In the future society, a means to verify the identity of the information owner is required at the beginning of most services that the information owner encounters, and the emergence and gradual spread of digital identification that proves the identity of the information owner is essential. In addition, as the utilization value of personal information increases, discussions on how to provide personal information are active. Therefore, there is a need for a personal information management method necessary for building a hyper-connected society that is safe from various hacking, forgery, alteration, and theft by allowing the owner to directly manage and provide personal information management. In this study, a decentralized identity information management model that overcomes the problems and limitations of the centralized identity management method of personal information and manages and selectively provides personal information by the information owner himself and implemented a smart personal information provision system(SPIPS: Smart Personal Information Provision System) using a smartphone.

• International Journal of Computer Science & Network Security
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• v.23 no.6
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• pp.181-192
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• 2023

Blockchain system brought innovation in the area of accounting, credit monitoring and trade secrets. Consensus algorithm that considered the central component of blockchain, significantly influences performance and security of blockchain system. In this paper we presented four consensus protocols specifically as Proof of Work (PoW), Proof of Stake (PoS), Delegated Proof of Stake (DPoS) and Practical Byzantine Fault-Tolerance (PBFT), we also reviewed different security threats that affect the performance of Consensus Protocols and precisely enlist their counter measures. Further we evaluated the performance of these Consensus Protocols in tabular form based on different parameters. At the end we discussed a comprehensive comparison of Consensus protocols in terms of Throughput, Latency and Scalability. We presume that our results can be beneficial to blockchain system and token economists, practitioners and researchers.