• Journal of Internet Computing and Services
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• v.20 no.6
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• pp.119-127
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• 2019

This paper proposes a new authentication model to solve the problem of personal information takeover and personal information theft by service providers using centralized servers for user authentication and management of personal information. The centralization issue is resolved by providing user authentication and information storage space through a decentralize platform, blockchain, and ensuring confidentiality of information through user-specific symmetric key encryption. The proposed model was implemented using the public-blockchain Ethereum and the web-based wallet extension MetaMask, and users access the Ethereum main network through the MetaMask on their browser and store their encrypted personal information in the Smart Contract. In the future, users will provide their personal information to the service provider through their Ethereum Account for the use of the new service, which will provide user authentication and personal information without subscription or a new authentication process. Service providers can reduce the costs of storing personal information and separate authentication methods, and prevent problems caused by personal information leakage.

• Smart Media Journal
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• v.9 no.1
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• pp.9-15
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• 2020

Recently there have been increasing attempts to apply blockchains to businesses and public institutions. Blockchain is a distributed shared ledger with excellent transparency and security of data and through consensus algorithm, the same data can be shared to all nodes in order. In this paper, Modified PBFT which does not modify the PBFT consensus algorithm is proposed. MPBFT is able to tolerate Byzantine faults on a private blockchain on an asynchronous network. Even with the increase of participating nodes, the network communication cost can be effectively maintained. Modified PBFT takes into account the characteristics of an asynchronous network environment where node-to-node trust is guaranteed. In response to the client's request, PBFT performed the entire participation broadcast several times, but Modified PBFT enabled consensus and authentication through the 2 / N leader. By applying the Modified PBFT consensus algorithm, the broadcast process can be simplified to maintain the minimum number of nodes for consensus and to efficiently manage network communication costs.

• The Journal of the Convergence on Culture Technology
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• v.6 no.4
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• pp.219-224
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• 2020

One of the main reasons for the commercial failure of various early blockchain-based art trade platforms, including Maecenas, is the lack of clear ways for owners to fully restore ownership of artworks. In this paper, we proposed a procedure for the owner of the artwork to rebuy shares and restore his or her entire ownership in the blockchain system. Using the proposed procedure, we can find a balanced price between the owner and investors, and then restore ownership through a public purchase of the stake. The balanced price can be induced by penalizing the owner for proposing unreasonably low price, and by rewarding investors for deciding reasonable prices. The proposed procedure of restoring ownership is expected to be utilized not only on the block chain-based art trading platform but also on the block chain-based trade platform in other applications.

• Journal of Digital Convergence
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• v.17 no.10
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• pp.13-21
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• 2019

The restricted network or the unbalanced distribution of spectrum is causing the problems of lack of spectrum resources and deterioration of the service quality. In addition, the existing centralized radio sharing method has not been a fundamental solution for radio sharing and is inefficient in terms of cost, convenience, and security. In this paper, we propose a blockchain-based spectrum sharing as a low-cost, trustworthy, high-efficiency platform that can distribute and share spectrum resources, and propose policies to realize this. In the spectrum sharing platform, spectrum information about Wi-Fi AP and LTE mobile hotspot is registered in the blockchain, and spectrum sharers and users can conclude peer-to-peer spectrum sharing contract quickly and efficiently through smart contract. The pay for the shared spectrum resources and reward for spectrum quality management open platform ecosystem to activate the circulation-sharing and it can provide a convenient and efficient public wireless infrastructure.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.33 no.6
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• pp.947-960
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• 2023

In Korea, traditional paper promissory notes are currently undergoing a transformation, being gradually replaced by electronic notes. This transformation is being steered under the Korea Financial Telecommunications Institute, a trusted authority. However, existing electronic systems have security vulnerabilities, including the risk of hacking and internal errors within the institute. To this end, we have defined a novel anonymous electronic promissory note system based on blockchain. We have constructed a concrete protocol and conducted security analysis of our protocol. Note that, in our protocol, every note information is committed so that the note remains undisclosed until the point of payment. Once the note information becomes public on the blockchain, it enables the detection of illicit activities, such as money laundering and tax evasion. Furthermore, our protocol incorporates a feature of split endorsement, which is a crucial functionality permitted by the Korean electronic note system. Consequently, our proposed protocol is suitable for practical applications in financial transactions.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.12
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• pp.1685-1689
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• 2018

In this research, 51% attack or majority attack is becoming an important security issue for proof of work based blockchains. Due to decentralized nature of blockchains, any attacks that shutdowns the network or which take control over the network is hard to prevent and assess. In this paper, different types of majority attack are summarized and the motivations behind the attacks are explained. To show the feasibility of the majority attack, we build an example mining machines that can take control over two of the public blockchains, Vertcoin and Monero.

• The Journal of Society for e-Business Studies
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• v.24 no.3
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• pp.73-86
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• 2019

After the 4th industrial revolution, the healthcare industry is striving to find new business models through new technologies. Among them, blockchain technology is one of the technologies that have great interest in the healthcare industry. Most providers of personal health record systems have difficulty in securing marketability due to various problems. Therefore, they try to integrate blockchain technology to develop new systems and gain marketability. However, blockchain has limitations in solving the problems of the personal health record system. In this study, we have designed a personalized health data management framework that enables information subjects to acquire full ownership rights of individual's health data, based on distributed ledger technology. For the framework design, we refer to the structure of R3 Corda. It was designed with a different network structure than the existing blockchain systems so that the node can be operated on the personal user's mobile device. This allows information subjects to directly store and manage their own data and share data with authorized network members. Through the proposed system, the information utilization of the healthcare industry can be improved and the public health promotion and medical technology development can be realized.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.4
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• pp.462-469
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• 2019

According to the survey of Ministry of the Interior and Safety in Korea, The number of public and private CCTV reached over ten million and is still increasing. Also with improving Image Processing Technology, it is possible to obtain diverse information. Recently, various services using CCTV are being provided. Therefore it is necessary to ensure CCTV image integrity. However there is no system to prove events in film yet. In this paper, we suggest system model that can manage, use and authenticate CCTV. This model allows a CCTV film to be verified by other nearby CCTVs' data. This model ensures film's integrity by using blockchain. And also, It addresses privacy problem in CCTV and file size problem in blockchain by using not large film data but much smaller analyzed data.

• KIPS Transactions on Computer and Communication Systems
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• v.9 no.12
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• pp.307-314
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• 2020

The video surveillance service is being widely deployed around our lives and the service stores sensitive data such as video streams in the cloud over the Internet or the centralized data store in an on-premise environment. The main concerning of these services is that the user should trust the service provider how secure the video or data is stored and handled without any concrete evidence. In this paper, we proposed the approach to protecting video by PKI (public key infrastructure) with a blockchain network. The video is encrypted by a symmetric key, then the key is shared through a blockchain network with taking advantage of the PKI mechanism. Therefore, the user can ensure the sensitive data is always kept secure and traceable in its lifecycle.

• International Journal of Computer Science & Network Security
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• v.21 no.6
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• pp.156-160
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• 2021

Every day brings a new challenge to the humanities. Life nowadays needs accuracy, privacy, integrity, authenticity, and security to run life systems especially the monetary system. Things now differ from previous centuries. Multiple varieties in digital banking have opened the new and most advanced innovations for human beings. The monetary system is going to developed day by day to facilitate the public. Electronic money has amazed the world and gave a challenge to central banking. For this purpose, there will be a need for strict security, information, and confidence. Blockchain technology has opened new gateways. Bitcoin has become the most famous digital currency, which has created a thunderstorm in digital marketing. Blockchain, as a new Financial Technology, has satisfied all the security issues and satisfied doing business in secure ways that encourage investors to invest and keep the world business wheel. Assessment of the sustainability of implementing Bitcoin in financial institutions will be discussed. Every new system has its pros and cons in which a clear vision of what we are about to use can be sought. Through this research paper, a demonstration of the monetary system evolution, the new ways of doing business, some evidence in a form of academic cases will be demonstrated through comparison a table, a suggested method to transfer to the new system in safe mode will be proposed, and a conclusion will be concluded.