• Journal of Korea Port Economic Association
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• v.19 no.1
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• pp.223-245
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• 2003

As a rapid development of electronic commerce transactions in these days, the security and private protection problems became more important matters under the electronic transaction base. Because electronic transaction using electronic documents be carried without direct person to person meeting, there can be the possibility to use other's identity illegally without notice, and very hard to verify authenticity of transaction as well. In addition, it is very hard to find out that the electronic documents on the process of submitting is forged documents or not, and also have much difficulty in maintaining transmitting secret. Therefore, to solve such problems on electronic commerce transactions and electronic documents, the digital signature and certification system with cryptography skill is inevitably necessary. As the wide use of digital signature together with beginning of digital government and financial transaction, not only the issuance of electronic certification, but certification market came to gradually expand. In Korea, after enacting digital signature act in 1999, the act contents were expanded to the wide range of contents complying with global standards from the end of 2001 to April, 2002, including the new clause of certification problems. And the act was put into operation now. Therefore, in this paper, we'd like to suggest development scheme through the investigation on electronic certification related problems, such as, concepts, procedures, service conditions here and abroad.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.11
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• pp.5537-5555
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• 2017

Having the characteristics of unlinkability, anonymity, and unforgeability, blind signatures are widely used for privacy-related applications such as electronic cash, electronic voting and electronic auction systems where to maintain the anonymity of the participants. Among these applications, the blinded message is needed for a certain purpose by which users delegate signing operation and communicate with each other in a trusted manner. This application leads to the need of proxy blind signature schemes. Proxy blind signature is an important type of cryptographic primitive to realize the properties of both blind signature and proxy signature. Over the past years, many proxy blind signature algorithms have been adopted to fulfill such task based on the discrete logarithm problem (DLP) and the elliptic curve discrete log problem (ECDLP), and most of the existing studies mainly aim to provide effective models to satisfy the security requirements concerning a single blinded message. Unlike many previous works, the proposed scheme applies the signcryption paradigm to the proxy blind signature technology for handling multiple blinded messages at a time based on elliptic curve cryptography (ECC). This innovative method thus has a higher level of security to achieve the security goals of both blind signature and proxy signature. Moreover, the evaluation results show that this proposed protocol is more efficient, consuming low communication overhead while increasing the volume of digital messages compared to the performance from other solutions. Due to these features, this design is able to be implemented in small low-power intelligent devices and very suitable and easily adoptable for e-system applications in pervasive mobile computing environment.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.5
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• pp.2628-2645
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• 2017

This paper proposes a new offline electronic payment (e-payment) system that satisfies the major security requirements of e-payment, i.e. anonymity, unlinkability, unforgeability, double spending control, conditional traceability, and fraud prevention. The central idea is the use of Hwang et al.'s RSA-based untraceable blind signature (BS), which disables the link between the e-coin and its owner and ensures the anonymity of both the customer and the merchant. It attaches an expiration, a deposit and the transaction dates to each e-coin in order to manage the database of the bank effectively, to correctly calculate the interest on the e-coin and to aid arbitration if a dishonest customer attempts to double-spend the coin. It also ensures the anonymity of the customer as long as the coin is spent legitimately. Only when a fraudulent e-coin transaction is detected can the bank, with the help of the central authority (a trusted entity), determine the identity of the dishonest customer. The system is referred to as offline since the bank does not need to be concurrently involved in transactions between a customer and a merchant. Finally, analyses of the performance of the prototype and the primary security requirements of the proposed system are also presented.

• Journal of the Korea Society of Computer and Information
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• v.18 no.7
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• pp.85-92
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• 2013

In this paper, on the basis of Guilin Wang's proxy signature scheme and the Schnorr blind signature, we propose a secure proxy blind signature scheme. A proxy blind signature scheme is a digital signature scheme which combines the properties of a proxy signature and a blind signature scheme. Guilin Wang proposed a provably secure proxy signature scheme, which is based on a two-party Schnorr signature scheme. Also, using the proposed proxy blind signature scheme, we propose the proxy agent system for the electronic voting. We show the proposed scheme satisfies the security properties of both the blind signature and the proxy signature scheme and is efficient and optimal proxy blind signature scheme.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.11 no.1
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• pp.73-85
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• 2001

Electronic check schemes are more efficient than electronic coin scheme with respect to computational costs and the amount of information exchanged. In spite of these, difficulties in making a refund reusable and in representing the face value of a check have discouraged its development. In this paper, a new online electronic check system is presented, which solves the above problems. This system uses the partially blind signature to provide user anonymity and to represent the face value of a check. The partially blind signature enables us to make the format of refunds and initially withdrawn checks identical. Thus, it allows refunds to be reused to buy goods without any limitatiosn. Both initially withdrawn checks and refunds in our system guarantee untraceability as well as unlinkability. We also use a one-time secret key as the serial number of a check to increase the efficiency of payments. The presented check system also provides multiple offline shopping sessions to minimize the number of online messages handled by a bank. During the multiple offline shopping session, we use a one-way accumulator to provide non-repudiation service. We also analyze our new systems our new system\`s security, efficiency, and atomicity.

• 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.

• Management & Information Systems Review
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• v.12
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• pp.1-15
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• 2003

As a rapid development of electronic commerce transactions in these days, the security and private protection problems became more important matters under the electronic transaction base. Because electronic transaction using electronic documents be carried without direct person to person meeting, there can be the possibility to use other's identity illegally without notice, and very hard to verify authenticity of transaction as well. In addition, it is very hard to find out that the electronic documents on the process of submitting is forged documents or not, and also have much difficulty in maintaining transmitting secret. Therefore, to solve such problems on electronic commerce transactions and electronic documents, the digital signature and certification system with cryptography skill is inevitably necessary. As the wide use of digital signature together with beginning of digital government and financial transaction, not only the issuance of electronic certification, but certification market came to gradually expand. In Korea, after enacting digital signature act in 1999, the act contents were expanded to the wide range of contents complying with global standards from the end of 2001 to April, 2002, including the new clause of certification problems. And the act was put into operation now. Therefore, in this paper, we'd like to suggest development scheme through the investigation on electronic certification related problems, such as, concepts, procedures, service conditions here and abroad.

• Journal of Korea Multimedia Society
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• v.23 no.9
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• pp.1201-1209
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• 2020

Based on the risk factor evaluation for the file format, this paper defines the procedures for presenting the long-term preservation plan for that format and the technical information registry necessary for building the system. This is a procedure to perform a risk assessment for the format, evaluate the risk, and select a long-term preservation strategy based on the information registered in the registry and information on the external signature and internal signature of the electronic record. We also reviewed the criteria for selecting appropriate long-term preservation strategies in the process and provided the criteria for adopting each detailed strategy of migration and emulation, which are long-term preservation strategies. And we implemented this process as a long-term preservation decision support system. This system can be used to provide guidelines for the maintenance, management, service and long-term preservation of information resources of electronic records in public institutions such as National Archives of Korea and Libraries.

• Journal of Korea Multimedia Society
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• v.12 no.6
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• pp.833-841
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• 2009

In this paper we propose a flexible video authentication scheme based on aggregate signature, which provides authenticity of a digital video by means of cryptographic signature to guarantee right of users. In contrast to previous works, the proposed scheme provides flexible usages on content distribution system, and it allows addition of new contents to the signed contents and deletion of some parts of the signed contents. A modification can be done by content owner or others. Although contents are modified by one or more users, our scheme can guarantee each user's right by aggregation of the each user's signatures. Moreover, proposed scheme has half size of Digital Signature Algorithm (DSA) with comparable security.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.9
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• pp.1781-1785
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• 2007

We propose a new enhanced graphical user interface and algorithm for dynamic signature verification using Smart-phone. Also, we describe the performance results of our dynamic signature verification system, which determine the authentication of signatures by comparing and analyzing various dynamic data shape of the signature, writing speed, slant of shape, and the order and number of strokes for personal signatures using an electronic pen, expecting the system to be understood and utilized widely in the industrial field.