• Journal of Information Technology Services
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• v.20 no.6
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• pp.17-43
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• 2021

Currently, various discussions are underway to establish a more advanced management system for public rental housing. Also, it calls for improvement methods for problems arising in management of the current rental housing system. In this regard, this study aims to evaluate determinants that affect user acceptance intention of blockchain technology to implement a new system that complements drawbacks of the current public rental housing system. The study uses the Unified Theory of Acceptance and Use of Technology (UTAUT) as a theoretical model; the study model utilizes three UTAUT variables -performance expectancy, social influence, and Facilitating conditions-, applies security, availability, and reliability that are perceived from blockchain technology as external parameters to facilitate understanding of user acceptance intention of blockchain technology, and evaluates whether innovativeness can regulate the influence of performance expectancy, social influence, and Facilitating conditions on user acceptance intention of blockchain technology. Based on the significant survey result where 274 IT technicians participated, the study applies structural equation modeling to explore structure of user acceptance intention in the blockchain-based management system for public rental housing. As a result, security-reliability and availability are found to factors as determinants for user acceptance intention, affecting implementation of the public rental housing management system, while innovativeness shows no significant statistical results related to regulation effect. This study has implications in that it understands characteristics of blockchain and empirically analyzes the relationship between the characteristics and acceptance intention to enable blockchain's contribution to activate the public rental housing management system in the future.

• Convergence Security Journal
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• v.19 no.5
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• pp.11-18
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• 2019

In current public blockchain, any node can see every blocks, so that public blockchain provider transparent property. However, some application requires the confidential information to be stored in the block. Therefore, this paper proposes a multi-layer blockchain that have the public block layer and the private block for confidential information. This paper suggests the requirement for encryption of private block. Also, this paper shows the t-of-n threshold cryptosystem without dealer who is trusted third party. Finally proposed scheme satisfies the requirements for encryption and fairness.

• Proceedings of the Korea Contents Association Conference
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• 2019.05a
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• pp.7-8
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• 2019

This paper presents a hybrid blockchain-based Identity Management Framework for devices in Microgrid. It incorporates the use of a Public and Private Blockchain platform to store and authenticate Microgrid device identities. It also emphasizes the shared responsibility of the manufacturers to provide the first layer of authentication for the devices they produce. Identities of each device are stored in the private and public Blockchain and authenticated using physically unclonable functions (PUF) and cryptographic functions.

• International Journal of Computer Science & Network Security
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• v.21 no.8
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• pp.111-118
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• 2021

Banking systems are sensitive to data privacy since users' data, if not well protected, may be used to perform fake transactions. Blockchains, public and private, are frequently used in such systems thanks to their efficiency and high security. Public blockchains fail to fully protect users' data, despite their power in the accuracy of the transactions. The private blockchain is better used to protect the privacy of the sensitive data. They are not open and they apply authorization to login into the blockchain. However, they have a lower security compared to public blockchain. We propose in this paper a hybrid public-private architecture that profits from network virtualization. The main novelty of this proposal is the use of network virtualization that helps to reduce the complexity and efficiency of the computations. Simulations have been conducted to evaluate the performance of the proposed solution. Findings prove the efficiency of the scheme in reducing complexity and enhancing data privacy by guarantee high security. The contribution conducted by this proposal is that the results are verified by the centralized controller that ensures a correct validation of the resulted blockchains. In addition, computation complexity is to be reduced by profiting from the cooperation performed by the virtual agents.

• Journal of Multimedia Information System
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• v.6 no.3
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• pp.139-146
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• 2019

This paper, wireless internet such as Wi-Fi has a vulnerability to security. Blockchain also means a 'Ledger' in which transaction information that occurs on a public or private network is encrypted and shared among the network participants. Blockchain maintains information integrity by making it impossible for a particular node to tamper with information arbitrarily, a feature that would result in changes in the overall blockchain hash value if any one transaction information that constitutes a block was changed. The complete sharing of information through a peer-to-peer network will also cripple hacking attempts from outside, targeting specialized nodes, and prepare for the "single point of failure" risk of the entire system being shut down. Due to the value of these Blockchain, various types of Blockchain are emerging, and related technology development efforts are also actively underway. Various business models such as public block chains such as Bitcoin, as well as private block chains that allow only certain authorized nodes to participate, or consortium block chains operated by a select few licensed groups, are being utilized. In terms of technological evolution, Blockchain also shows the potential to grow beyond cryptocurrency into an online platform that allows all kinds of transactions with the advent of 'Smart Contract'. By using Blockchain technology, the company makes suggestions to overcome the vulnerability of wireless Internet.

• Journal of Information Technology Services
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• v.18 no.1
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• pp.45-61
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• 2019

Blockchain technology, which enables transparent transactions among individuals without central control, opens up diverse business possibilities. It is also expected that blockchain will have a ripple effect on the entire area of society including finance, manufacturing, distribution, and the public sector. Previous studies related to the blockchain also deals with its functional features and application to industrial and public fields. In the new technology such as blockchain, it is necessary to know what social perception is in order to create technological development environment, but there is a lack of research on it. Therefore, this study aims to find out the implications for industrial and policy direction by analyzing issues related to the blockchain in South Korea and the US through text mining. From these two countries, we collected text data related to blockchain in online communities and internet articles. Then, we did co-occurrence analysis and topic modeling on them respectively. As a result of this study, we have found common points and differences in keywords and topics extracted from social media in the two countries. Based on them, we can offer helpful suggestions for building a sound blockchain ecosystem, and directions for future research.

• Convergence Security Journal
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• v.20 no.4
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• pp.177-186
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• 2020

In current public blockchain, any node can see every blocks, so that public blockchain provider transparent property. However, some application requires the confidential information to be stored in the block. Therefore, this paper proposes a multi-layer blockchain that have the public block layer and the private block for confidential information. This paper suggests the requirement for encryption of private block. Also, this paper shows the t-of-n threshold cryptosystem without dealer who is trusted third party. Moreover, the delegated node who has key information can be withdraw the delegated node group or a new delegated node can join in the delegated node group. Therefore, the paper proposes an efficient key information resharing scheme for withdraw and join. Finally proposed scheme satisfies the requirements for encryption and fairness.

• 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.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.1
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• pp.55-60
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• 2020

In this paper, we propose an access control system using cryptography as a method to protect personal data in public blockchain. The proposed system is designed to encrypt data according to the access policy, store it in the blockchain, and decrypt only the person who satisfy the access policy. In order to improve performance and scalability, an encryption mechanism is implemented outside the blockchain. Therefore, data access performance could be preserved while cryptographic operations executed Furthermore it can also improve the scalability by adding new access control modules while preserving the current configuration of blockchain network. The encryption scheme is based on the attribute-based encryption (ABE). However, unlike the traditional ABE, the "retention period", is incorporated into the access structure to ensure the right to be forgotten. In addition, symmetric key cryptograpic algorithms are used for the performance of ABE. We implemented the proposed system in a public blockchain and conducted the performance evaluation.

• The Journal of Society for e-Business Studies
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• v.24 no.4
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• pp.1-16
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• 2019

Blockchain technology prevents tampering of central authorities that manage voting process, enhancing trust in the vote results. This technology enables citizens to participate more directly in the areas where delegation was inevitable due to the difficulties in polling fair and trustworthy public opinions. There are many projects around the world proposing to implement voting system for public decision making using blockchain technology. The blockchain voting system is expected to work as a transparent and fair channel for polling public opinions, which will transform the public decision-making process and governance. Korean National Pension Service (NPS) recently introduced stewardship code to better represent the interest of beneficiaries. However, because of the mistrust in governance of NPS, introduction of stewardship code is facing criticism for potential misuse of their voting rights against the interest of beneficiaries and for government's interference with corporate management. This study proposes a voting system applying blockchain technology for polling the opinions of National Pension Fund's beneficiaries to support public decision-making, and discusses social and institutional conditions for implementation of the proposed system.