• 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.

• Journal of Intelligence and Information Systems
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• v.24 no.2
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• pp.195-220
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• 2018

In this study, we conducted an empirical analysis of the factors that affect the change of Bitcoin Closing Price. Previous studies have focused on the security of the block chain system, the economic ripple effects caused by the cryptocurrency, legal implications and the acceptance to consumer about cryptocurrency. In various area, cryptocurrency was studied and many researcher and people including government, regardless of country, try to utilize cryptocurrency and applicate to its technology. Despite of rapid and dramatic change of cryptocurrencies' price and growth of its effects, empirical study of the factors affecting the price change of cryptocurrency was lack. There were only a few limited studies, business reports and short working paper. Therefore, it is necessary to determine what factors effect on the change of closing Bitcoin price. For analysis, hypotheses were constructed from three dimensions of consumer, industry, and macroeconomics for analysis, and time series data were collected for variables of each dimension. Consumer variables consist of search traffic of Bitcoin, search traffic of bitcoin ban, search traffic of ransomware and search traffic of war. Industry variables were composed GPU vendors' stock price and memory vendors' stock price. Macro-economy variables were contemplated such as U.S. dollar index futures, FOMC policy interest rates, WTI crude oil price. Using above variables, we did times series regression analysis to find relationship between those variables and change of Bitcoin Closing Price. Before the regression analysis to confirm the relationship between change of Bitcoin Closing Price and the other variables, we performed the Unit-root test to verifying the stationary of time series data to avoid spurious regression. Then, using a stationary data, we did the regression analysis. As a result of the analysis, we found that the change of Bitcoin Closing Price has negative effects with search traffic of 'Bitcoin Ban' and US dollar index futures, while change of GPU vendors' stock price and change of WTI crude oil price showed positive effects. In case of 'Bitcoin Ban', it is directly determining the maintenance or abolition of Bitcoin trade, that's why consumer reacted sensitively and effected on change of Bitcoin Closing Price. GPU is raw material of Bitcoin mining. Generally, increasing of companies' stock price means the growth of the sales of those companies' products and services. GPU's demands increases are indirectly reflected to the GPU vendors' stock price. Making an interpretation, a rise in prices of GPU has put a crimp on the mining of Bitcoin. Consequently, GPU vendors' stock price effects on change of Bitcoin Closing Price. And we confirmed U.S. dollar index futures moved in the opposite direction with change of Bitcoin Closing Price. It moved like Gold. Gold was considered as a safe asset to consumers and it means consumer think that Bitcoin is a safe asset. On the other hand, WTI oil price went Bitcoin Closing Price's way. It implies that Bitcoin are regarded to investment asset like raw materials market's product. The variables that were not significant in the analysis were search traffic of bitcoin, search traffic of ransomware, search traffic of war, memory vendor's stock price, FOMC policy interest rates. In search traffic of bitcoin, we judged that interest in Bitcoin did not lead to purchase of Bitcoin. It means search traffic of Bitcoin didn't reflect all of Bitcoin's demand. So, it implies there are some factors that regulate and mediate the Bitcoin purchase. In search traffic of ransomware, it is hard to say concern of ransomware determined the whole Bitcoin demand. Because only a few people damaged by ransomware and the percentage of hackers requiring Bitcoins was low. Also, its information security problem is events not continuous issues. Search traffic of war was not significant. Like stock market, generally it has negative in relation to war, but exceptional case like Gulf war, it moves stakeholders' profits and environment. We think that this is the same case. In memory vendor stock price, this is because memory vendors' flagship products were not VRAM which is essential for Bitcoin supply. In FOMC policy interest rates, when the interest rate is low, the surplus capital is invested in securities such as stocks. But Bitcoin' price fluctuation was large so it is not recognized as an attractive commodity to the consumers. In addition, unlike the stock market, Bitcoin doesn't have any safety policy such as Circuit breakers and Sidecar. Through this study, we verified what factors effect on change of Bitcoin Closing Price, and interpreted why such change happened. In addition, establishing the characteristics of Bitcoin as a safe asset and investment asset, we provide a guide how consumer, financial institution and government organization approach to the cryptocurrency. Moreover, corroborating the factors affecting change of Bitcoin Closing Price, researcher will get some clue and qualification which factors have to be considered in hereafter cryptocurrency study.

• Journal of Internet Computing and Services
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• v.23 no.5
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• pp.103-110
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• 2022

Botnets have been exploited for a variety of purposes, ranging from monetary demands to national threats, and are one of the most threatening types of attacks in the field of cybersecurity. Botnets emerged as a centralized structure in the early days and then evolved to a P2P structure. Bitcoin is the first online cryptocurrency based on blockchain technology announced by Satoshi Nakamoto in 2008 and is the most widely used cryptocurrency in the world. As the number of Bitcoin users increases, the size of Bitcoin network is also expanding. As a result, a botnet using the Bitcoin network as a C&C channel has emerged, and related research has been recently reported. In this study, we propose an encrypted botnet C&C communication mechanism and technique in the Bitcoin network and validate the proposed method by conducting performance evaluation through various experiments after building it on the Bitcoin testnet. By this research, we want to inform the possibility of botnet threats in the Bitcoin network to researchers.

• Journal of Information Technology Services
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• v.16 no.2
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• pp.1-20
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• 2017

A bitcoin-based technology named blockchain is garnering attention in various industries as a cost-effective measure in strengthening security and a reliable technology medium. Blockchain technology will play a critical role in the Fourth Industrial Revolution, and IT technology is expected to bring fundamental changes. This study focuses on the characteristics of blockchain technology and the effects of the intention to accept its technology in an empirical manner. The aspects of the technology are organized by researching blockchain technology and theories of technology acceptability and previous studies were used as guidelines to create the research model and propose the hypothesis. The research model is based on UTAUT with a set-up of 5 factors for performance expectancy and effort expectancy. For empirical analysis, a survey was conducted on 283 IT workers in Korea, To examine the hypothesis structural equation modeling was used performance expectancy was influenced by security, reliability, diversity, and economic efficiency while effort expectancy was influenced by reliability and economic efficiency. Performance expectancy, social influence, facilitating conditions affect the intention to accept. Innovativeness of an organization and control effects are influenced as well. The present study aims to provide practical guidance as supplementary research in utilizing blockchain technology, and the limitations of the study and future research possibilities are discussed as well.

• Journal of Internet Computing and Services
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• v.21 no.6
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• pp.51-56
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• 2020

Cryptocurrencies, including Bitcoin, has decentralization, distribution and P2P properties unlike traditional currencies relies on trusted central party such as banks. All transactions are stored transparently and distributively, hence all participants can check the details of those transactions. Due to the properties of cryptographic hash function, deletion or modification of the stored transations is computationally not possible. However, cryptocurrencies only provide pseudonymity, not anonymity, which is provided by traditional currencies. Therefore many researches were conducted to provide anonymity to cryptocurrencies such as mix-based methods. In this paper, I will propose more efficient hybrid mix-based method for anonymity than previous mix-based one.

• International Journal of Computer Science & Network Security
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• v.22 no.5
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• pp.234-244
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• 2022

Tourism products involve the transfer of money that is flowing to countries with partners or borders, which do not possess any relations surrounding their business environment. Suitable platforms must be generated by the tourism industry, which are beneficial to users when their demands are satisfied based on financial, technology, knowledge, and industry matters. Intermediaries are applied to alleviate different problems that are related to the non-fulfilment of contracts of existing users and service providers who are offering their services and represent a reliable third party. However, it is significant that intermediaries must be reliable when charges are incurred for any possible commission. Cryptocurrencies rely on blockchain technology to provide smoothness in money interchange without the need for reliable third parties. This interchange allows an increasing number of different new forms, which are related to different customer-to-customer transactions. The study attempts to provide an appropriate answer to the main research question, which is: 'Will the widespread adoption of cryptocurrencies bring new types of customer-to-customer markets from a technological, organizational, and environmental perspective?'.

• Journal of Internet Computing and Services
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• v.20 no.6
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• pp.105-117
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• 2019

Bitcoin, which can be classified as a cryptocurrency, has attracted attention from various industries because it is an innovative digital currency and the beginning of a Blockchain system. However, as the research on Bitcoin progressed, several security vulnerabilities and possible attacks were analyzed. Among them, the security problem caused by the transparency of the Blockchain database prevents the Blockchain system from being applied to various fields. This vulnerability is further classified as the weak anonymity of participating nodes and privacy problem due to disclosure of transaction details. In recent years, several countermeasures have been developed against these vulnerabilities. In this paper, we first describe the main features of the public and private Blockchain, and explain privacy, unlinkability and anonymity. And, three public Blockchain platforms, Dash, Zcash and Monero which are derived from Bitcoin, and Hyperledger Fabric which is a private Blockchain platform, are examined. And we analyze the operating principles of the protocols applied on each platform. In addition, we classify the applied technologies into anonymity and privacy protection in detail, analyze the advantages and disadvantages, and compare the features and relative performance of the platforms based on the computational speed of the applied cryptographic mechanisms.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.4
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• pp.179-188
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• 2018

Recently, blockchain technology has been recognized as one of the most important issues for the 4th Industrial Revolution which can be represented by Artificial Intelligence and Internet of Things. Cryptocurrency, named Bitcoin, was the first successful implementation of blockchain, and it triggered the emergence of various cryptocurrencies. In addition, blockchain technology has been applied to various applications such as finance, healthcare, manufacturing, logistics as well as public services. Distributed consensus algorithm is an essential component in blockchain, and it enables all nodes belonging to blockchain network to make an agreement, which means all nodes have the same information. For example, Bitcoin uses a consensus algorithm called Proof-of-Work (PoW) that gives possession of block generation based on the computational volume committed by nodes. However, energy consumption for block generation in PoW has drastically increased due to the growth of computational performance to prove the possession of block. Although many other distributed consensus algorithms including Proof-of-Stake are suggested, they have their own advantages and limitations, and new research works should be proposed to overcome these limitations. For doing this, above all things, we need to establish an evaluation method existing distributed consensus algorithms. Based on this motivation, in this work, we suggest and analyze assessment items by classifying them as efficiency and safety perspectives for investigating existing distributed consensus algorithms. Furthermore, we suggest new assessment criteria and their implementation methods, which can be used for a baseline for improving performance of existing distributed consensus algorithms and designing new consensus algorithm in future.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.34 no.4
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• pp.641-649
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• 2024

This paper addresses the issue of anonymity protection in the trading of Real-World Asset (RWA) tokens, a prominent topic in the cryptocurrency market in recent years. The principle of transparency inherent in blockchain technology makes it challenging to ensure the anonymity of traders. Although there have been instances in existing blockchain research where mixer services have been utilized to protect the privacy of Fungible Tokens (FTs), and prior studies have explored the privacy protection for Non-Fungible Tokens (NFTs), RWA tokens, which can embody characteristics of both FTs and NFTs and are tied to physical assets, present a complex challenge in achieving the goal of anonymity protection through any single method. This paper proposes a hypothetical token trading platform, ARTeX, and describes the trading process to analyze measures for protecting the anonymity of RWA token transactions.