• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.13 no.7
• /
• pp.3733-3755
• /
• 2019

E-cash has its merits comparing with other payment modes. However, there are two problems, which are how to achieve practical/complete tracing and how to achieve it in compact E-cash. First, the bank and the TTP (i.e., trusted third party) have different duties and powers in the reality. Therefore, double-spending tracing is bank's task, while unconditional tracing is TTP's task. In addition, it is desirable to provide lost-coin tracing before they are spent by anyone else. Second, compact E-cash is an efficient scheme, but tracing the coins from double-spender without TTP results in poor efficiency. To solve the problems, we present a compact E-cash scheme. For this purpose, we design an embedded structure of knowledge proof based on a new pseudorandom function and improve the computation complexity from O(k) to O(1). Double-spending tracing needs leaking dishonest users' secret knowledge, but preserving the anonymity of honest users needs zero-knowledge property, and our special knowledge proof achieves it with complete proofs. Moreover, the design is also useful for other applications, where both keeping zero-knowledge and leaking information are necessary.

• The KIPS Transactions:PartD
• /
• v.15D no.1
• /
• pp.121-130
• /
• 2008

In line with the enhanced weight and variety of electronic commerce in business activities, new type of payment settlement and banking system which will enable to store, create and transfer values from the existing method of payment settlement is highly required. Cyber Banking system draws strong attention being the solution of there requirements. The existing Cyber Banking system has the difficulty of operation, administration, in addition to the problem of initial facility investment of big amount, resulted from the usage of the current business process. As the existing Cyber Bank system is unable to carry out the function of storing, creating, and transferring values due to the adoption conventional credit card system instead of the application of non-stop payment system between the seller and buyer. As a result, current Cyber Bank system still imply the deficiency of non-performing cash payment function on internet. This paper describes (1) an integrated application process, One Process One Input (OPOI) which is essential for software development of the Cyber Bank, (2) an application process of payment settlement system to be applied to the electronic commerce in Internet. And then, with these for a basis, (3) design and implementation of payment settlement system through CyberBank for Electronic Commerce. Consequently, by means of this suggested process, we could attempt to solve the problem of existing Cyber Bank system and further to explore the possibility of advanced Cyber Banking being the non-stop payment settlement system. The effectiveness of this suggested system has been practically confirmed.

• International conference on construction engineering and project management
• /
• 2011.02a
• /
• pp.526-533
• /
• 2011

Contracting is said to be a high-risk business, and a common cause of business failure is related to cash management. A contractor's financial viability depends heavily on how actual payments from an owner deviate from those defined in the contract. The paper presents a method for contractors to evaluate the punctuality and fullness of owner payments based on historical behaviour. It does this by classifying owners according to their late and incomplete payment practices. A payment profile of an owner, in the form of aging claims submitted by the contractor, is used as a basis for the method's development. Regression trees are constructed based on three predictor variables, namely, the average time to payment following a claim, the total amount ending up being paid within a certain period and the level of variability in claim response times. The Tree package in the publicly available R program is used for building the trees. The analysis is particularly useful for contractors at the pre-tendering stage, when contractors predict the likely payment scenario in an upcoming project. Based on the method, the contractor can decide whether to tender or not tender, or adjust its financial preparations accordingly. The paper is a contribution in risk management applied to claim and dispute resolution practice. It is argued that by contractors having a better understanding of owner payment behaviour, fewer disputes and contractor business failures will occur.

• The Transactions of the Korea Information Processing Society
• /
• v.5 no.11
• /
• pp.2921-2929
• /
• 1998

We propose an efficient off-line electronic cash system based on the certificate issued by Certificate Authority. It satisfies all the basic requirements for electronic payment system such as cash unforgeability, cash anonymity, double spending detection, no framing, etc. Our proposed system is very computationally efficient in the sense that: (1) the number of exponentiation operation imposed on the user during withdrawal phase is much smaller than any existing off-line electronic cash schemes, (2) all the computation of user's during withdrawal phase can be performed by off-line pre-processing. So the proposed system is suitable to be implemented by smart cards in both memory and computation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2003.05a
• /
• pp.824-827
• /
• 2003

With a rapid development of Information Telecommunication technique, network communication environment has been greatly improved. People come to feel more convinient to purchase products through Internet. Accordingly, various kinds of electronic payment systems have been developed and used. In this paper, we propose an algorithm which not only can associate the broker system with an electronic cash user, but also regenerate all amount of money previously paid using technique such as Meta-Message recovery and a RSA Blind Signature based on discrete logarithm problem.

• Journal of Korea Multimedia Society
• /
• v.7 no.8
• /
• pp.1107-1119
• /
• 2004

There is Electronic-cash system as important payment means in Electronic-commerce and the requirement of electronic cash is independence, transferability, divisibility etc. This is important requirement in DRM to provide contents as a same requirement to contents. Because contents itself can see that requirement of Electronic-cash can be transferred the control of to contents requirement as monetary concept. Can apply equally in reproduction and copy for contents, anonymity user's access etc, and several relations. In this paper, wish to put by value that is equal about Electronic-cash and contents, and apply concept of Electronic-cash through this and present DRM model after examine requirement of Electronic-cash and DRM's requirement. Concept used in this paper left copy use authority to use hierarchic tree structure and endowed anonymity for contents and anonymity about user for anonymous user. Finally, examines and compares and analyzes proposed existing methods.

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

• THE INTERNATIONAL COMMERCE & LAW REVIEW
• /
• v.46
• /
• pp.133-158
• /
• 2010

Independent guarantee is a creation of the need from the both sides, i.e. the applicant (principal debtor) and the beneficiary (creditor). The former used to have to deposit cash in favor of the beneficiary in case of his default, which laid a burden on his liquidity while the latter still wanted to have the equivalent to cash. Independent guarantee satisfied the both parties by freeing the applicant of a deposit and maintaining the beneficiary's right at the same time. The fact that independent guarantee has three payment mechanisms is not widely known to the public. They are (i) payment on first demand, (ii) payment upon submission of third-party documents, (iii) payment upon submission of an arbitral or court decision. From the applicant's point of view, the order in his favor is (iii), followed by (ii) and (i). As there shouldn't be a case where one party is at a disadvantage against the other, useful insight is being sought for the benefit of the applicant. First, the applicant can offer his intention to provide a payment mechanism (ii) or (iii) rather than (i) if he must deliver it. Second, if the beneficiary still wants to have (i) and the applicant is in a position not to reject it, the latter should thoroughly check any provisions that may work against him later. Third, the applicant could use counterbalancing provisions in underlying contract to cope with protective clauses in the guarantees. Forth, the applicant should review the beneficiary's sincerity to prevent unfair calling risks. The applicant may use an ECA(Export Credit Agency) in his country to which he can transfer not only unfair calling risks, but also political risks. On the other hand, a bank needs to keep the following advice in mind. The foremost important thing for the bank not to forget is that it provides a guarantee as a service provider, not as a responsible party for the feasibility of the project, etc. Credit risk of the applicant should require the greatest attention when issuing a guarantee: the bank should look into the possibility that it can procure immediate reimbursement from its customers after payment to the beneficiary. Second, the applicant's ability to complete the project should be reviewed by checking its track records, techniques and reputation, etc. Third, the bank may also use an ECA to cover the beneficiary's unfair calling risks as well as political risks. In the case of Korea, as Korea Export Insurance Corporation(KEIC) can cover all the risks mentioned above, the bank could use its service called 'Export Bond Insurance.' What's better for the bank is that ECA cover can enhance the bank's asset quality by putting it zero on its risk weighted asset.

• Proceedings of the Korean Institute Of Construction Engineering and Management
• /
• autumn
• /
• pp.35-41
• /
• 2002

This research introduces the development of a project-level cash flow forecasting model in construction stage based on the planned earned value and the cost from a general contractors view on a jobsite. Most previous models have been developed to assist contractors in their pre-tendering or planning stage cash flow forecasts. The critical key to cash flow forecasting at the project level is how to build a cash-out model. The basic concept is to use moving weights of cost categories in a budget over project duration. The cost categories are classified to compile resources with almost the same time lags that are based on contracting payment conditions and credit times given by suppliers or venders. For cash-in, net planned monthly-earned values are simply transferred to the cash-in forecast, to be applied there with billing time and retention money. Validation of the model involves applying data from on-going 4 projects in progress for 12 months. Based on the results of the comparative analyses through the simulation of the proposed model and the existing models, the proposed model is more accurate, flexible and simpler than traditional models to the employee of construction jobsite who is not oriented financial knowledge.

• Journal of Advanced Navigation Technology
• /
• v.11 no.1
• /
• pp.112-117
• /
• 2007

The Internet leads the transformation of the all-over social life with its radical diffusion and development. Moreover, it can be more focussed on the electronic commerce using the Internet - a new type of commerce, which is diffusion and developing. In the paper, we propose an electronic payment protocol with a network-type electronic-cash based on Public Key Infrastructure(PKI). The proposed protocol overcomes the problem of NetBill which deals with only contents and can't ensure anonymity. It also prevents illegal copy and distribution and insures the greatest safety by means of giving a certification number to the digital contents offered on the on-line.