• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.6
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• pp.718-723
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• 2018

In a positive Internet of Medical Things (IoMT) environment, by combining the latest computer network technology with IoT technology, remote health care such as health care and monitoring is improved through the provision of quality medical information services. In this paper, we identified and compared the platforms applied with blockchain and presented the results of developing the product distribution de-centralized DApp. In the process, we developed a distribution platform that can use blockchain technology to identify product fraud, manage data, manage customers' information, prevent forgery, track transaction history, and facilitate product transactions.

• 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.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.7
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• pp.1935-1950
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• 2023

The arrival of the Internet of Things and 5G technology enables users to rely on edge computing platforms to process massive data. Data sharing based on edge computing refines the efficiency of data collection and analysis, saves the communication cost of data transmission back and forth, but also causes the privacy leakage of a lot of user data. Based on attribute-based encryption and blockchain technology, we design a fine-grained access control scheme for data in edge computing, which has the characteristics of verifiability, support for outsourcing decryption and user attribute revocation. User attributes are authorized by multi-attribute authorization, and the calculation of outsourcing decryption in attribute encryption is completed by edge server, which reduces the computing cost of end users. Meanwhile, We implemented the user's attribute revocation process through the dual encryption process of attribute authority and blockchain. Compared with other schemes, our scheme can manage users' attributes more flexibly. Blockchain technology also ensures the verifiability in the process of outsourcing decryption, which reduces the space occupied by ciphertext compared with other schemes. Meanwhile, the user attribute revocation scheme realizes the dynamic management of user attribute and protects the privacy of user attribute.

• KIPS Transactions on Computer and Communication Systems
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• v.11 no.2
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• pp.51-58
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• 2022

Blockchain technology is a system in which data from users participating in blockchain networks is distributed and stored. Bitcoin and Ethereum are attracting global attention, and the utilization of blockchain is expected to be endless. However, the need for blockchain data privacy protection is emerging in various financial, medical, and real estate sectors that process personal information due to the transparency of disclosing all data in the blockchain to network participants. Although studies using smart contracts, homomorphic encryption, and cryptographic key methods have been mainly conducted to protect existing blockchain data privacy, this paper proposes data privacy using matrix character relocation techniques differentiated from existing papers. The approach proposed in this paper consists largely of two methods: how to relocate the original data to matrix characters, how to return the deployed data to the original. Through qualitative experiments, we evaluate the safety of the approach proposed in this paper, and demonstrate that matrix character relocation will be sufficiently applicable in private blockchain environments by measuring the time it takes to revert applied data to original data.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.34 no.2
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• pp.289-299
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• 2024

Blockchains are not efficient for real-time processing because the growing number of transactions and users delays many computations and network communications. This study proposes a cloud proxy server, so that legitimate users can use blockchain as well as reduce network latency. To proceed with a blockchain transaction, the blockchain copy server verifies all transaction-related data, but the cloud proxy server verifies legitimate users with a simple zero-knowledge proof algorithm, enabling efficient blockchain real-time processing. The cloud proxy server can support blockchain anonymity, security, and scalability that can verify legitimate users with the proposed zero-knowledge proof by receiving the registered key pair of the blockchain user. In the proposed research analysis, blockchain-based cloud proxy server reduces network latency compared to previous studies and key processing on cloud proxy servers reduces the cost of key computation compared to previous studies.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.34 no.5
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• pp.1021-1035
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• 2024

This paper proposes the TEE-BOP (Trusted Execution Environment-Based Blockchain Offline Payment) protocol for blockchain-based offline payments. TEE-BOP securely manages offline balances within a Trusted Execution Environment (TEE) and efficiently verifies initial deposit proofs recorded on the blockchain using Merkle trees. Additionally, it ensures secure and tamper-proof transactions in offline environments by guaranteeing the reliability of keys and the system through TEE Attestation. Unlike previous studies, TEE-BOP enhances real-world applicability by eliminating dependence on central authorities and avoiding assumptions of ideal models. The protocol solves the double-spending problem through multi-layered defense mechanisms and addresses forgery prevention by allowing recipients to directly verify data consistency between the TEE and the blockchain. This enables reliable blockchain-based offline payments in areas with unstable network infrastructure. It demonstrates that this research can expand the application of blockchain technology and contribute to improving access to financial services in developing countries or disaster situations.

• Information Systems Review
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• v.23 no.3
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• pp.97-125
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• 2021

Blockchain is a core technology to solve personal information leakage and data management issues, which are limitations of existing Genomic Sequencing services. Due to continuous cost reduction and deregulation, the market size of Genomic Sequencing has been increasing, also the potential of services is expected to increase when Blockchain's security and connectivity are combined. We created our research model by combining the Technology Acceptance Model (TAM) and the Innovation Resistance Theory also analyzed the factors affecting the acceptance intention and innovation resistance of the Blockchain Based Genomic Sequencing Information Platform. A survey was conducted on 150 potential users of Blockchain and Genomic Sequencing services. The analysis was conducted by setting the four Blockchain variables: Security, transparency, availability, and diversity). Also, we set the Perceived Usefulness, Perceived risk, and Perceived Complexity for Technology Acceptance and Innovation Resistance variables and analyzed the effect of the characteristics of the Blockchain on acceptance intention and innovation resistance through these variables. Through this analysis, key variables that need to be considered important to reduce resistance and increase acceptance intention could be identified. This study presents innovation factors that should be considered in companies preparing a new Blockchain Based Genomic Sequencing Information Platform.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.32 no.3
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• pp.513-525
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• 2022

The immutability of blockchain is core elements of security of blockchain and guarantee data integrity. However, the characteristic that the data recoreded once in the blockchain cannot be modified has place for abuse by a specific user. In fact improper contents that is inappropriate to be recorded on the blockchain, such as harmful data and user personal data, is exposed on Bitcoin. As a way to manage improper content existing in the blockchain, there is a redactable blockchain using chameleon hash proposed for the first time by Ateniese. The redactable blockchain meet the right to be forgotten of GDPR by allowing data modification and deletion. Recently, Research on personal data management is being conducted in a redactable blockchain. Research by Jia et al. proposed a model that enables users to manage their personal data in the redactable blockchain. However, semi trusted regulators, which are blockchain participation nodes, have powerful authority in the blockchain, such as modification rights and deprivation of transaction rights for all blocks, which may cause side effects. In this paper, to weaken the authority of regulators in Y. Jia et al., we propose a method of authority subject altering and authority sharing, and propose a redactable blockchain-based authority change and access control system model based on applicable scenarios.

• International Journal of Advanced Culture Technology
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• v.10 no.2
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• pp.233-239
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• 2022

Recently, research is being conducted on the rapid service provision and reliability of the instance-based rather than the existing IP-based structure. Research is mainly conducted through Block cloud, a platform that combines service-centric networking (SCN) and blockchain. In addition, the Internet of Things network has been proposed as a fog computing environment in the structure of the existing cloud computing. Fog computing is an environment suitable for real-time information processing. In this paper, we propose a new Internet network structure based on fog computing that requires real-time for rapid processing of IoT services. The proposed system applies IoTA, the third-generation blockchain based on DAG, to the block cloud. In addition, we want to propose a basic model of the object block chain and check the application services of electric vehicles.

• Journal of Information Processing Systems
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• v.16 no.2
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• pp.301-317
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• 2020

An enterprise patch-management system (PMS) typically supplies a single point of failure (SPOF) of centralization structure. However, a Blockchain system offers features of decentralization, transaction integrity, user certification, and a smart chaincode. This study proposes a Hyperledger Fabric Blockchain-based distributed patch-management system and verifies its technological feasibility through prototyping, so that all participating users can be protected from various threats. In particular, by adopting a private chain for patch file set management, it is designed as a Blockchain system that can enhance security, log management, latest status supervision and monitoring functions. In addition, it uses a Hyperledger Fabric that owns a practical Byzantine fault tolerant consensus algorithm, and implements the functions of upload patch file set, download patch file set, and audit patch file history, which are major features of PMS, as a smart contract (chaincode), and verified this operation. The distributed ledger structure of Blockchain-based PMS can be a solution for distributor and client authentication and forgery problems, SPOF problem, and distribution record reliability problem. It not only presents an alternative to dealing with central management server loads and failures, but it also provides a higher level of security and availability.