• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.5
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• pp.604-612
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• 2019

PKI Internet banking is used to have users register their public keys with the banking server together with the identity information, and verify the signature for both user and transaction authentications by using the registered public keys. Although the Blockchain-based financial systems such as Bitcoin adopt similar digital signature-based authentication scheme, there is no server that participants can register public keys with because they perform P2P payment transactions. The purpose of this paper is to identify the advantages and disadvantages of the Blockchain-based payment transactions by analyzing the differences between the most common PKI Internet banking and Blockchain payment systems. Based on the analysis, this paper suggests the issues that need to be enhanced from the aspects of architecture and security in order for Blockchain payment transaction systems to be applied universally.

• Journal of Internet Computing and Services
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• v.20 no.5
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• pp.121-132
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• 2019

As the 4th industrial age enters, the number of IoT devices is exploding. Accordingly, the importance of security is also increasing in proportion to the increasing number of security incidents of IoT devices. However, due to the limited performance of IoT devices, there are limitations to applying existing security solutions. Therefore, a new automatic firmware distribution solution is needed to solve this problem. To solve this problem, we propose a new automatic firmware update system that uses a hybrid blockchain that combines a public blockchain and a private blockchain. The public blockchain allows various firmware providers to distribute firmware using a common system. Private blockchain solves the transaction overload problem of the public blockchain and facilitates the management of IoT devices. It also uses distributed file storage to ensure high availability without failing. Therefore, this system is expected to be very effective for improving the security of IoT devices.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.30 no.1
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• pp.87-100
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• 2020

Researches on Post-quantum blockchain, which is a synthesis of blockchain and post-quantum cryptography[1], are relatively unrevealed areas but have needs to be studied with the regard to the quantum computers. However there could be several fundamental problems, e.g. unsustainably large size of public key and signature, or too lengthy time for sign and verification, if any post-quantum cryptography is adopted to the existing blockchain to implement post-quantum blockchain. Thus, a new method was proposed in this paper that produces fixed length of references for massive signatures and corresponding public keys to enable relatively lightweight transactions. This paper proposed the mechanism that included a new transaction structure and protocols, and demonstrated a post-quantum blockchain that the proposed mechanism was adopted. Through this research, it could enhance compatibility of blockchain regarding post-quantum digital signature, possibly reducing weights of the whole blockchain.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.5
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• pp.161-169
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• 2018

This study presents a time synchronization system in decentralized structure by using the blockchain, a core technology of Bitcoin introduced by Satoshi Nakamoto in 2008. In this study, Getting away from existing time synchronization system in centralized structure, A blockchain network has completely decentralized structure using public blockchain. In decentralized structure, Only certain peers among the peers that participate in a blockchain network access the NTP server. Therefore, others can synchronize time without having to go to public network. Furthermore if appropriate time synchronization cycles are established for each peer, time synchronization can be maintained even when connection to public network is completely lost. A time synchronization system in this study has advantages of p2p system and can be also guaranteed reliability and stability because it used digital signature, merkle tree, consensus algorithm which are core characteristics of block chains.

• Journal of Internet of Things and Convergence
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• v.9 no.2
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• pp.77-82
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• 2023

As the method of collecting and utilizing structured and unstructured data develops due to the influence of the Fourth Industrial Revolution, unwanted personal information data is also being collected and utilized, and hackers are attempting various attacks to steal information. As a result, the importance of information protection has increased, and various protection techniques have emerged, among which many studies have been conducted using decentralized techniques of blockchain and various algorithms to strengthen the security of biometric authentication techniques. This paper proposed a public blockchain biometric authentication system that allows users to protect their data in a safer biometric authentication method in the public blockchain and use it in the blockchain through signature with authenticated information.

• Journal of Multimedia Information System
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• v.6 no.3
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• pp.125-130
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• 2019

In this paper, Blockchain is mentioned as the next-generation core IT technology. As an immature technology, there are not many practical use cases, but it is expected to be widely applied in various industries such as cryptocurrency, finance, public, etc. to increase efficiency and enable new services that did not exist in the past. Nevertheless, the generalization of blockchain technology is still difficult. In particular, from the viewpoint of personal information protection, GDPR of Europe, etc., is becoming stronger. Considering that the core of the blockchain is the change of information sharing and processing method, it is very important how the blockchain can affect, especially from the viewpoint of privacy, and how the Privacy Act can be applied to the blockchain. However, the discussion on this part also seems to be insufficient. Therefore, in this paper, blockchain By analyzing the implications and implications of technologies and services using them from the perspective of the Privacy Act, we will discuss how the blockchain will be used to prevent leakage of privacy.

• KIPS Transactions on Computer and Communication Systems
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• v.12 no.8
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• pp.253-262
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• 2023

E-voting is a concept that includes actions such as kiosk voting at a designated place and internet voting at an unspecified place, and has emerged to alleviate the problem of consuming a lot of resources and costs when conducting offline voting. Using E-voting has many advantages over existing voting systems, such as increased efficiency in voting and ballot counting, reduced costs, increased voting rate, and reduced errors. However, centralized E-voting has not received attention in public elections and voting on corporate agendas because the results of voting cannot be trusted due to concerns about data forgery and modulation and hacking by others. In order to solve this problem, recently, by designing an E-voting system using blockchain, research has been actively conducted to supplement concepts lacking in existing E-voting, such as increasing the reliability of voting information and securing transparency. In this paper, we proposed an electronic voting system that introduced hybrid blockchain that uses public and private blockchains in convergence. A hybrid blockchain can solve the problem of slow transaction processing speed, expensive fee by using a private blockchain, and can supplement for the lack of transparency and data integrity of transactions through a public blockchain. In addition, the proposed system is implemented as BaaS to ensure the ease of type conversion and scalability of blockchain and to provide powerful computing power. BaaS is an abbreviation of Blockchain as a Service, which is one of the cloud computing technologies and means a service that provides a blockchain platform ans software through the internet. In this paper, in order to evaluate the feasibility, the proposed system and domestic and foreign electronic voting-related studies are compared and analyzed in terms of blockchain type, anonymity, verification process, smart contract, performance, and scalability.

• Asia pacific journal of information systems
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• v.30 no.1
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• pp.21-30
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• 2020

Bitcoin (BTC) is a type of cryptocurrency that supports transaction/payment of virtual money between BTC users without the presence of a central authority or any third party like bank. It uses some cryptographic techniques namely public- and private-keys, digital signature and cryptographic-hash functions, and they are used for making secure transactions and maintaining distributed public ledger called blockchain. In BTC system, each transaction signed by sender is broadcasted over the P2P (Peer-to-Peer) Bitcoin network and a set of such transactions collected over a period is hashed together with the previous block/other values to form a block known as candidate block, where the first block known as genesis-block was created independently. Before a candidate block to be the part of existing blockchain (chaining of blocks), a computation-intensive hard problem needs to be solved. A number of miners try to solve it and a winner earns some BTCs as inspiration. The miners have high computing and hardware resources, and they play key roles in BTC for blockchain formation. This paper mainly analyses the underlying cryptographic techniques, identifies some weaknesses and proposes their enhancements. For these, two modifications of BTC are suggested ― (i) All BTC users must use digital certificates for their authentication and (ii) Winning miner must give signature on the compressed data of a block for authentication of public blocks/blockchain.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.9
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• pp.1264-1270
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• 2018

Blockchain is a technology that directly connects each node to P2P method, except for the central server. A public blockchain is one of the blockchain types, anyone can participate without any restriction. If some node find nonce, which node can broadcasted data to all nodes. At this time, if a node that finds a nonce hides malicious code in the block, all nodes participating in the chain may be infected with malicious code due to the characteristics of the decentralization system of the blockchain. In this paper, to solve the problem that hackers can participate as an any node, we propose that a user with malicious intent can not participate as a node through a firewall with AI technology. This will improve the reliability of the propagated data over existing data.

• The Journal of Fisheries Business Administration
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• v.52 no.1
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• pp.65-82
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• 2021

This study utilizes the IPA (Importance-Performance Analysis) method to assess the importance, possibility, and urgency of using blockchain technology for fisheries sectors and the related policies. Based on a field survey targeting experts and stakeholders in the fisheries and blockchain technology sectors, the following major results and corresponding implications are drawn. First of all, the respondents of our survey have an outlook that the introduction and utilization of blockchain will be required in four major parts. These parts include i) the seafood' information system managed by the government or public institutions, ii) traceability and certification process for domestic and foreign seafoods, iii) meeting the need of seafood safety from consumers, and iv) taking prompt actions to seafood safety related accidents. Next, the seafood information system managed by the government or public institutions has been limited in maintaining information consistency and continuity once the fisheries ministries and departments are integrated, closed or partially transferred. Thus, it is assessed that the technology will be able to improve consistency and continuity of the seafood information in case of applying blockchain to the seafood information management system. This result that blockchain is necessary for the seafood information system have a significant implication in Korea's seafood management which has been independently controlled until now. Lastly, the application of blockchain to seafood traceability and certification systems has the most well-known cases through international and domestic pilot projects, and the results of our survey reflect this reality. Our results contribute to showing an additonal characteristics of blockchain in the fisheries sector, resulting in the possiblity that blockchain can be used for taking swift steps in the event of seafood safety accidents and meeting the need of seafood consumers for safety.