• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.14
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• pp.397-426
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• 2000

Since the internet is open to public in 1990, electronic commerce(EC) user has increase rapidly. Now EC is considered not only as communication method but also as new economical activities. EC is a kind of new commerce model which uses electronic means. And EC has global characteristics so that many country's legislation which regulates it differently makes an obstacle to vital of EC. The purpose of this study is to examine legal problems of internet electronic commerce. First, there are some legal problems whether electronic document has same legal function like traditional documents. Second, electronic signature must has authenticity, integrity, non-repudiation, writing and confidentiality in order to use looks like common signature. Finally, electronic contract is concluded on principle of mutual agreement. It is apparent that the concept of arrival is applied to the date and place in conclusion of electronic contract.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.8
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• pp.2010-2026
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• 2013

The combination of biometrics and cryptography gains a lot of attention from both academic and industry community. The noisy biometric measurement makes traditional identity based cryptosystems unusable. Also the extraction of key from biometric information is difficult. In this paper, we propose an efficient biometric identity based signature scheme (Bio-IBS) that makes use of fuzzy extractor to generate the key from a biometric data of user. The component fuzzy extraction is based on error correction code. We also prove that the security of suggested scheme is reduced to computational Diffie-Hellman (CDH) assumption instead of other strong assumptions. Meanwhile, the comparison with existing schemes shows that efficiency of the system is enhanced.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.1014-1017
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• 2003

In this paper, after the crypto acceleration board of the server-termination type is designed, we implement the Elliptic Curve Digital Signature Algorithm on the board that serves data integrity and user authentication. For implementing ECDSA, we use crypto co-processor, MPC180, to reduce the computation burden of main Processor (MPC860) on the board. By using crypto co-processor, the computation efficiency in case prime field is improved more between 90 and 100 times than the software library and between 20 and 90 times in case binary field. Our result is expect to apply for SSL acceleration board.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.1 no.1
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• pp.3-15
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• 1991

in 1984 Shamir proposed the concept of ID(identity)-based cryptosystem and digital signature scheme wich does not require any public file for storing the user' s public keys. In this paper, the concept of the ID-based cryptosystem based on discrete logarithm problem using the conven-tional public-key cryptosystems is described, and the implementation method of the ID-based cryptosystem is also presented. The new digital signaturw schme based on the ID-based crypto-system is proposed and possible atacks are considered and analyzed for the security of digital signature scheme. The proposed ID-based schemes are particularrly useful for smart card and personal identification card application.

• Journal of Digital Contents Society
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• v.9 no.1
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• pp.125-130
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• 2008

User web service is increasing by development of internet technology. Quantity of encrypted data that transmitted through the network are increasing by development of encipherment technology. We have many problems; it is caused by technical development and service increase of user requests. It is like that, we have reliability of contents and illegality copy problem of internet contents in web application system. It is contents protection skills in web that encipherment technology, authentication and digital signature. We need message encoding and secret key for solve vulnerability of encipherment in web application system. In this paper, we propose a distributed secure system that can data confidentiality and user authentication. It prevent performance degradation from bottle neck in encipherment server, and improve service quality.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.5
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• pp.1049-1062
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• 2019

The national accredited certificate is a user certificate issued based on the user's personal information, which has been identified in advance, and has become a universal authentication method used for most electronic financial transactions and user authentication. And it contributed a lot to the use of e-government and domestic service. However, due to the lack of web standards on how to use, it was inconvenient to install a separate plug-in, and efforts to improve it have been continued. In this paper, we attempt to solve the problem of certificate usage environment by presenting the certificate digital signature method using the extension of the FIDO2 (Fast Identity Online v2) client to authentication protocol (CTAP) specification.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.11
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• pp.4573-4594
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• 2020

Announcement protocol in Internet of Vehicles (IoV) is an intelligent application to enhance public safety, alleviate traffic jams and improve transportation quality. It requires communication between vehicles, roadside units and pedestrian to disseminate safety-related messages. However, as vehicles connected to internet, it makes them accessible globally to a potential adversary. Safety-related application requires a message to be reliable, however it may intrude the privacy of a vehicle. Contrarily, if some misbehaviour emerges, the malicious vehicles must be able to traceable and revoke from the network. This is a contradiction between privacy and accountability since the privacy of a user should be preserved. For a secure communication among intelligent entities, we propose a novel announcement protocol in IoV using group signature. To the best of our knowledge, our work is the first comprehensive construction of an announcement protocol in IoV that deploys group signature. We show that our protocol efficiently solves these conflicting security requirements of message reliability, privacy and accountability using 5G communication channel. The performance analysis and simulation results signify our work achieves performance efficiency in IoV communication.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.10
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• pp.4250-4267
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• 2015

Although many revocable group signature schemes has been proposed in vehicular ad hoc networks (VANETs), the existing schemes suffer from long computation delay on revocation that they cannot adapt to the dynamic VANETs. Based on Chinese remainder theorem and Schnorr signature algorithm, this paper proposes an efficient revocable group signature scheme in VANETs. In the proposed scheme, it only need to update the corresponding group public key when a member quits the group, and in the meanwhile the key pairs of unchanged group members are not influenced. Furthermore, this scheme can achieve privacy protection by making use of blind certificates. Before joining to the VANETs, users register at local trusted agencies (LTAs) with their ID cards to obtain blind certificates. The blind certificate will be submitted to road-side units (RSUs) to verify the legality of users. Thus, the real identities of users can be protected. In addition, if there is a dispute, users can combine to submit open applications to RSUs against a disputed member. And LTAs can determine the real identity of the disputed member. Moreover, since the key pairs employed by a user are different in different groups, attackers are not able to track the movement of users with the obtained public keys in a group. Furthermore, performance analysis shows that proposed scheme has less computation cost than existing schemes.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.11 no.6
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• pp.41-51
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• 2001

Group signature schemes allow a group member to sign messages anonymously on behalf of the group. In case of dispute, only a designated group manager can reveal the identity of the member. During last decade, group signature schemes have been intensively investigated in the literature and applied to various applications. However, there has been no scheme properly handling the situation that a group member wants to leave a group or is excluded by a group manager. As noted in[3], the complexity of member deletion stands in the way of real world applications of group signatures and the member deletion problem has been a pressing open problem. In this paper we propose an efficient group signature scheme that allows member deletion. The length of the group public key and the size of signatures all independent of the size of the group and the security of the scheme relies on the RSA assumption. In addition, the method of tracing all signatures of a specific member is introduced.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.4
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• pp.743-751
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• 2017

As smart phones are becoming popular, an operating system is being used at wearable devices, home appliances and smart TVs. A user is able to use various applications on devices with operating system, but there is an increased threat of hacker. Thus, the technology for detecting the forgery of applications is becoming more important on operating system. To detect the forgery of the application, a digital signature technology is used on the filed of application digital signature. According to W3C recommendation, the signing process of application digital signature must be performed at least twice, and the applications which are signed by the application digital signature have to be validated for all signature files when the application is installed in the operating system. Hence, the performance of the application digital signature validation system is closely related to the installer performance on the operating system. Existing validation system has performance degradation due to redundancy of integrity verification among application components. This research was conducted to improve the performance of the application digital signature validation system. The proposal of validation system which is applied proxy system shows a performance improvement compared to the existing verification system.