• The Journal of Society for e-Business Studies
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• v.25 no.2
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• pp.109-126
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• 2020

This study attempts to find out the characteristics of digital currency and currency transformation through the analytical descriptions of the literature. In the early days of the emergence of new currency, market-oriented autonomous monetary adjustment was made along with various attempts by the private sector, and then government-centered central currency management and coordination were made for the national monopoly of profits and power. Digital currency can be seen as the emergence of a new form of money that will bring about paradigm changes. CBDC can be divided into direct and indirect types. CBDC is expected to require a strategic approach by the government or firm as it will bring about changes in the ecosystem of related industries. Libra is a stablecoin designed to minimize price fluctuations, and if it succeeds in commercializing it, it is expected to bring about revolutionary changes in the financial industry around the world.

• Journal of KIISE:Information Networking
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• v.30 no.2
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• pp.207-221
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• 2003

A hash chain is highly efficient, attractive structure to use in electronic cash. Previous systems using hash chain were, however, either credit-based vendor-specific cash or debit-based general-purpose cash which lacks efficiency due to double spending problem. In this paper, we propose a new divisible cash system using hash chain. This newly proposed cash is general-purpose, debit-based, anonymous, and offline. The efficiency of the system results from its capacity to pay variable amounts with no additional costs. A client always performs a single blind signature in the withdrawal phase, independent of the length of the chain. During payment, a client performs a single challenge-and-response or generates a single signature, independent of the amount paid. This system provides a new refund mechanism, which uses a refund ticket, that allows clients to refund the unspent part of the chain without revealing any connection to the spent part.

• Journal of KIISE:Computer Systems and Theory
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• v.30 no.7_8
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• pp.408-416
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• 2003

An electronic cash system has to provide the security, to prevent the double spending and to support the divisibility of electronic cash for the easy of use. Divisible electronic cash system allows an electronic cash to be divided into subdivisions. Each subdivision is worth any desired value, but all values must add up to the original cash value. Divisible scheme brings some advantages. It reduces to make the change and also there is no necessity that a customer must withdraw a cash of the desired value whenever transactions occur. In this paper, we present an electronic cash protocol which provides the divisibility based on the double hash chain technique. Electronic cash is constructed in the form of coins. Coins, generated by the double hush chain, have different denominations. The divisibility based on the double hash chain technique. Electronic cash is constructed in the form of coins. Coins, generated by the double hash chain, have different denominations. The divisibility of an electronic cash is satisfied by the payment certificate, which is a pair of bank´s proxy signature received from the bank. When a customer pays the coin of subdivision, the fairness of that coin is certified by a customer´s signing instead of a bank. Although the proposed method does not guarantee user´s anonymity, it generates coins which cannot be forged, and the customer can use an electronic cash conveniently and efficiently with its divisibility.

• The Journal of Information Technology
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• v.3 no.3
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• pp.77-88
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• 2000

Electronic Commerce increased rapidly according to the growing popularity of Internet. but payment system are not changed. Now main payment system of electronic commerce are credit card and cyber banking system. Then credit card has some problems safety, privacy etc, and cyber banking system has some problem also. We need new payment system to Electronic Commerce. The merit of electronic money are more capacity, more secure, more reliable, quick and easy to update, secure off-line processing, enabling technology etc than credit card and cyber banking system. And so many countries began using experiment of electronic money and our country began July KOEX building. But it has some problems (standardization, safety of payment, etc). Therefor we must make nile about electronic money in order to standardization and safety of payment. After then electronic money are used widely in electronic commerce.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.9 no.1
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• pp.103-114
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• 1999

Recently, various prototypes for electronic commerce are realized and its related researches are active under the present condition which it is increasing for the reality of its extended applications. First of all, actual demands are increasing for more secure and efficient electronic payment systems. Electronic cash, one of the Electronic payment systems, must have several properties like real money. Blind signature scheme by D. Chaum stands for the methods of obtaining privacy. In this paper, we propose a method for obtaining the blind signature based on the Elliptic Curve Cryptosystems, where the crytosystems are known as solving some problems of conventional crytosystems in views of computation time and key space. Also, we present a method for the divisibility of the electronic cash using our proposal by re-signing spare cash. Thus applying the proposed method, we can develop an efficient electronic payment systems.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.11 no.3
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• pp.33-44
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• 2001

E-commerce has various advantages such as saving the cost and no constraint on time and space, unlike real-world commerce. On the other hand, e-commerce has some important issues to solve since the commerce is conducted on the cyberspace. The issues are a mutual confidence of parties participating in the commerce as well as a method of payments. On early days, electronic cash was designed using blind digital signature to protect the personal information from being exposed and to provide the perfect anonymity for user. In this paper, a new blind signature scheme based on Feige-Fiat-Shamir digital signature is proposed, which is very efficient compared with the other schemes in terms of the computational complexity. Also, a traceable Electronic Cash System which is based on the proposed blind digital signature is designed, which has a nice feature of identifying the spender in case of using the money illegally.

• Proceedings of the CALSEC Conference
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• 2001.02a
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• pp.297-304
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• 2001

비자인터내셔날이 실시한 조사에 따르면, 전자화폐의 성공요건은 다음과 같다. - 대량발급 및 사용 ; 카드, 가맹점, 유용성(Utility) - 비용감소 ; 카드, 단말기 - 다기능카드 : 다양한 기능 제공, 개방형칩 카드체제(Visa Open Platform) - 국제 호환성 □ Options for migration - upward compatibility(중략)

• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.6
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• pp.125-135
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• 2002

The electronic payment system based on blind signature is susceptible to the blackmailing attack as opposed to keep the lifestyle of users private. In this paper. we suggest an efficient electronic cash system using a blind XTR-DSA scheme, which improves the method of defeating blackmailing in online electronic cash systems of ［6,9］. In case of blackmailing, to issue the marked coins we use the blind XTR-DSA scheme at withdrawal. In ［6,9］, to cheat the blackmailer who takes the marked coins the decryption key of a user had to be transferred to the Bank. But in our proposed method the delivery of the decryption key is not required. Also, in the most serious attack of blackmailing. kidnapping, we can defeat blackmailing with a relatively high probability of 13/18 compared with 1/2 in ［9］ and 2/3 in ［6］. If an optimal extension field of XTR suggested in ［7］ is used, then we can implement our system more efficiently.

• Proceedings of the Korea Multimedia Society Conference
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• 2000.04a
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• pp.107-110
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• 2000

사이버 공간에서 이루어지는 전자상거래에서 중요하게 여겨지는 전자화폐 시스템은 사용자의 익명성을 기본적으로 제공하고 있다. 하지만 이러한 익명성으로 인해 각종 범죄 활동에 이용하려는 시도가 발생할 수 있다. 따라서, 시화적, 경제적인 범죄로의 이용가능성 때문에 익명성 제어에 관한 연구는 필수적이다. 이에 본 논문은 사용자 추적은 물론 동전 추적도 할 수 있는 새로운 프로토콜로 제안한다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10a
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• pp.358-360
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• 2004

최근 전자상거래의 활성화와 더불어 기존의 유선인터넷에서 시용하고 있는 전자지갑(S/W) 등 전자상거래 방식에서 Smart Card나 이동통신 단말기와 같은 독립적인 유/무선 단말을 사용하는 전자지불 시스템에 대한 관심이 고조되고 있다. 본 연구에서는 전자지불 시스템에 Bluetooth를 이용하여 안전한 사용자 인증 및 종단간의 보안을 제공 전자화폐의 발행/지불이 가능한 전자지불 시스템의 모델을 제시하고자 한다. 각 단말의 서브셋(subset)으로 Bluetooth 컨트롤 시스템과 이를 이용하는 전자지불 시스템으로서 전자지갑 및 전자화폐 발행기/지동판매기를 구현하여 각각의 보안 통신과 전자화폐의 발행/지불이 가능함을 나타냈다. 구현 결과물은 실제 전자지불 시스템에 적용이 가능할 것으로 보인다.