• The Journal of the Korea Contents Association
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• v.5 no.1
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• pp.55-63
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• 2005

In undeniable digital signature scheme, the signature can not be verified without the signer's cooperation. The undeniable signature scheme can be used to computerize many applications which can not be done by a conventional digital signature scheme. In this study, we propose the undeniable digital multi-signature scheme which requires many signers and designated verifier The multi-signature can be verified only in cooperation with all signers. The proposed scheme satisfies undeniable property and it is secure against active attacks such as modification and denial of the multi-signature by signers. We also propose copyright protection method of co-authored digital contents as an application of the proposed scheme.

• Proceedings of the Korea Contents Association Conference
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• 2004.05a
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• pp.261-267
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• 2004

In undeniable digital signature scheme, the signature can not be verified without the signer's cooperation. The undeniable signature scheme can be used to computerize many applications which can not be done by a conventional digital signature scheme. In this study, we propose the undeniable digital multi-signature scheme which requires many signers and designated verifier. The multi-signature can be verified only in cooperation with all signers. The proposed scheme satisfies undeniable property and it is secure against active attacks such as modification and denial of the multi-signature by signers. We also discuss practical applications such as joint copyright protection on digital contents.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.3
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• pp.549-555
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• 2007

A digital signature scheme provides integrity of the document, authentication and non-repudiation of a signer. Usually the key for digital signature is stored in hard disk or removal disk storage. The drawback of this approach is that the signer can let the agent to sign instead of the signer by providing the key information. It can be abused in applications such as electronic election. In this paper, we propose the undeniable biometric digital multi-signature scheme suitable for applications where the signer should not make an agent sign instead of himself/herself. The undeniable multi-signature scheme requires many signers and only the designated user can confirm the authenticity of multi-signature. The proposed scheme satisfies undeniable property and it is secure against active attacks such as modification and denial of the multi-signature by signers. As the key is generated through the signer's fingerprint image, it's also secure against signing by an agent.

• Proceedings of the Korea Multimedia Society Conference
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• 2000.04a
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• pp.111-116
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• 2000

컴퓨터네트워크를 통한 정보의 이동이 빈번한 오늘날, 중요 정보를 지키는 정보 보호 기술의 요구는 점차 늘어나고 있다. 이에 따라, 통신망 상의 프라이버시 보호, 기밀성, 무결성 같은 개인정보보호를 위해서 필수적인 암호학적 도구로 디지털 서명이 이용되고 있다. 본 논문에서는 이산대수 문제의 어려움에 기반하여, 디지털 서명대상을 2명에서 n명으로 확대한 다중서명 기법에 서명자 전원의 동의 없이는 서명을 검증할 수 없는 부정할 수 없는 서명의 기능을 부여한다. 이는 전자, 선거, 전자 현금 등 보다 복잡하고 민감한 사회적 영역에 적용될 수 있을 것이다.

• The Journal of Korean Association of Computer Education
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• v.8 no.4
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• pp.97-105
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• 2005

In this study, the undeniable digital multi-signature scheme based on the discrete logarithms is proposed. The proposed multi-signature scheme satisfies undeniability and is secure against active attacks such as fabrication and denial of multi-signature by signers. It is suitable for electronic election scheme in which several administrators are required. Especially in case of dispute among voters and administrators, the proposed scheme can resolve it due to the undeniable property. It can provide fair electronic election by minimizing the role of voting center, and can enable user-oriented electronic election.

• Journal of Digital Convergence
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• v.10 no.2
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• pp.161-169
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• 2012

It requires a lot of costs and manpower to manage the election system. The electronic voting scheme is needed to make the election system to be economic and fair. Especially, wide spread use of smart phones and wireless networks makes the mobile voting is of major concern. In mobile voting scheme, a smart phone user can vote regardless of the places. In this paper, the mobile voting scheme is proposed where candidates can guarantee fairness of the election system. We analyze mobile voting requirements and create the mobile ID which has legal binding forces and PKI based digital signature keys. In the proposed scheme, a voter's ballot is signed by all candidates using undeniable multi-signature scheme. During the counting stage, the multi-signature on the ballot is not verified without help of all candidates.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.5
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• pp.1670-1676
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• 2010

It is easy to reproduce and manipulate the digital contents. It's difficult to distinguish the original contents with a pirate one. A digital signature scheme is used to protect the contents author's ownership and to provide secure contents distribution. Generally, the digital contents is completed with many authors' help. It's necessary to apply a cryptographic method for protecting co-authors' rights and interests. In this paper, the biometric based convertible undeniable multi-signature scheme is proposed. In the proposed scheme, keys are generated by using a signer's biometric data. Consigning the private key to another signer is infeasible. Signers must participate in signature generation and verification stages. Our scheme also provides signature conversion protocol in which the undeniable signature is converted to the ordinary one. For applications, we show how the proposed scheme is used to protect co-authors' rights and to distribute the contents securely.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.10A
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• pp.1706-1716
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• 2001

이동에이전트 시스템은 기하급수적으로 증가하는 분산처리 환경과 이동컴퓨팅에 기여할 수 있다는 점으로 인해 주목받고 있는 기술이지만, 심각한 보안문제를 안고 있다. 본 논문에서는 ID 기반의 디지털 다중 서명 기술을 이용하여 이동 에이전트 시스템의 보안문제에 대한 효율적인 해결책을 제시하고자 한다. 이를 위하여 본 연구는 이동 에이전트 시스템이 가질 수 있는 보안 위협 요소를 분석하였다. 이러한 보안 위협은 적절한 보안 기술의 적용으로 해결될 수 있을 것으로 판단된다. 따라서 본 논문은 여러 사용자가 공동의 메시지를 전자적으로 서명하는 보안 기술인 디지털 다중 서명(Digital Multi-signature)기법과 ID에 기반한 키(key) 분배 기법을 이용하여 이동 에이전트 시스템의 보안 문제를 해결하기 위한 새로운 방법을 제안한다. 제안된 이동 에이전트 보안 프로토콜은 키 분배 및 관리의 단순화, 인증 절차의 단순화, 에이전트 실행 플랫폼의 인증과 송수신 부인 방지 기능을 제공, 생명성을 보장, 실행 결과 데이터의 기밀성, 무결성의 보장한다. 그리고 에이전트 실해의 전 단계를 매 시스템마다 검증함으로써 변경 또는 삭제시 곧바로 탐지한다.

• Proceedings of the Korean Information Science Society Conference
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• 2000.10c
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• pp.591-593
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• 2000

Mobile Agent System은 최근 각광받기 시작한 새로운 컴퓨팅 기법으로서 서버의 과부하를 줄이고, 네트워크 이벤트의 발생을 줄이면서 필요한 서비스를 사용자에게 지원하기 위한 해결책으로 연구되고 있다. 이동에이전트시스템은 해결해야할 많은 과제들이 있으나 그 중에서 주요한 문제로 인식되고 있는 것이 보안 문제이다. 본 논문은 이동에이전트시스템의 보안 고려사항을 분석하고, 공개키 기반의 암호시스템과 일반향함수를 사용하는 디지털 다중서명 기법을 적용하여 이동에이전트 시스템의 보안구조를 제안한다.

• The KIPS Transactions:PartC
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• v.10C no.1
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• pp.17-26
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• 2003

Mobile agent system comes into the spotlight since it contributes largely to mobile computing on distributed network environment. However, this system has a number of significant security Problems. In this Paper, we analyze suity attacks to mobile agent system Presented by NIST[3]. In order to protect this system from them, we suggest a security protocol for mobile agent system by employing R based key distribution and digital multi-signature scheme. To solve these problems described in NIST, securities for mobile agent and agent platform shouid be accomplished. Comparing with other protocols, our protocol performs both of these securities, while other protocols mentioned only one of them. Proposed Protocol satisfies simplicity of key management, providing security service such as confidentiality, integrity, authentication and preventing reputation, liveness guarantee, protection of excution-result data and preventing replay attack. Furthermore, it is designed to detect message modification immediately by verifying each step of agent execution at a corresponding server.