• Journal of KIISE:Information Networking
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• v.29 no.4
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• pp.333-345
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• 2002

As computers and networks become popular, distributing information on the Internet is common in our daily life. Also, the explosion of the Internet, of wireless digital communication and data exchange on Internet has rapidly changed the way we connect with other people. But secure mail is gaining popularity abroad and domestically because of their nature of providing security. That is. It has been used a variety of fields such as general mail and e-mail for advertisement. But, As the data transmitted on network can be easily opened or forged with simple operations. Most of existing e-mail system don't have any security on the transmitted information. Thus, security mail system need to provide security including message encryption, content integrity, message origin authentication, and non-repudiation. In this paper, we design and implement secure mail system with secure key agreement algorithm, non-repudiation service, and encryption capability to provide services for certification of delivery and certification of content as well as the basic security services.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.11 no.2
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• pp.27-35
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• 2001

Based on the development of mobile communication, the future mobile communication systems are expected to provide higher quality of multimedia services for users than today\`s systems. Therefore, many technical factors are needed in this systems. Especially the secrecy and the safety would be obtained through the introduction of the security for mobile communication. In this paper, we presents a digital nominative proxy signature scheme that processes a user\`s digital signature and encryption using the proxy-agent who has more computational power than origins in mobile communication. The proposed scheme provides non-repudiation and prevents creating illegal signature by the origin and proxy-agent in a phase of proxy signature processing. Also this scheme satisfies the confidentiality and safety in the mobile communication through a confirming signature by the right receiver.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2002.11a
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• pp.495-498
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• 2002

The need for network protection, accounting and resource management in foreign administrative domain requires appropriate security services. In this paper, we propose an access control protocol to support the authentication between mobile node and visiting subnet. Our hybrid way of approach aims to reduce computational overhead and minimize the use of network bandwidth. We also propose non-certificate based public-key cryptography to provide non-repudiation, which does not require CRL retrieval and certificate validation.

• ETRI Journal
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• v.38 no.4
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• pp.724-734
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• 2016

To achieve confidentiality, integrity, authentication, and non-repudiation simultaneously, the concept of signcryption was introduced by combining encryption and a signature in a single scheme. Certificate-based encryption schemes are designed to resolve the key escrow problem of identity-based encryption, as well as to simplify the certificate management problem in traditional public key cryptosystems. In this paper, we propose a new certificate-based signcryption scheme that has been proved to be secure against adaptive chosen ciphertext attacks and existentially unforgeable against chosen-message attacks in the random oracle model. Our scheme is not based on pairing and thus is efficient and practical. Furthermore, it allows a signcrypted message to be immediately verified by the public key of the sender. This means that verification and decryption of the signcrypted message are decoupled. To the best of our knowledge, this is the first signcryption scheme without pairing to have this feature.

• The Journal of Society for e-Business Studies
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• v.6 no.3
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• pp.101-113
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• 2001

Security is very important in EC(Electronic Commerce) environment because exchanged information(that is transaction details, private data, charges data(card-no, accounts), etc) is various and is very sensitive. So, In this paper, we propose Secure-ReXpis(Reliable St excellent Xh3 Processing Infrastructure) System that transfer message and support Message Level Security(Encryption/Decryption and Digital Signature). And we implement Message Confidentiality Service, User Authentication ＆ Message Integrity Service and Non-Repudiation Service among the various Security Services. This system support XML message format and EDI message, WEB Data and Private Format Data, etc.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.3
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• pp.333-340
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• 1999

이 논문에서는 송수신 부인봉쇄와 내용은닉 서명의 기본 개념과 공평한 비밀정보 교환을 위한 프로토콜인 불확정 전송 프로토콜에 대하여 소개하였다. Lein등이 제안한 검증 가능한 불확정 전송 프로토콜은 대화형 전송 방식을 사용하기 때문에 통신량이 많이 발생한다. 이러한 문제를 해결하기 위하여 M.Bellare & S. Micali가 제안한 비대화형 불확정 전송을 확장하여 믿을 수 없는 두 통신 주체간에 안전하게 비밀 정보를 전송할수 있고 , 송수신자간의 단 한번의 통신으로 이루어지는 검증 가능한 비대화형 불확정 전송 프로토콜을 제안하고, 추후 송수신 사실의 부인에 대한 문제가 발생할 경우 이를 중재할 수 있는 새로운 송수신 부인봉쇄 기능을 갖는 검증 가능한 비대화형 불확정 전송 프로토콜을 제안한고, 제안한 프로토콜에 대하여 안전성을 분석하였다.

• The Journal of Information Technology
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• v.4 no.4
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• pp.25-35
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• 2001

This paper presents a digital signature scheme for document image which directly embeds a signature onto the document. The time to take in signature is reduced by spreading of signature. Non-repudiation in origin, the 3rd condition of digital signature is realized by proposed digital signature scheme. The transmitter embeds the signature secretly and transfers it and the receiver makes a check of any forgery on the signature and the document, This scheme is compatible with the ITU-T.4(CCITT G3 or G4 facsimile standards).

• Review of KIISC
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• v.14 no.2
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• pp.57-77
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• 2004

최근, 인터넷의 보급이 일반화되면서 네트워크를 통해 다양한 전자상거래 서비스가 활성화되고 있다. 이러한 서비스는 전송되는 정보의 기밀성(confidentiality), 인증(authentication), 무결성(integrity), 부인봉쇄(non-repudiation)등의 정보보안 서비스를 제공하기 위해 암호기술이 요구된다. 이러한 암호기술의 안전성은 공개되어 있는 암호 알고리즘에 의존하는 것이 아니라, 암호 알고리즘에 사용된 키에 의해 좌우된다. 또한, 암호통신을 이용하는 개체가 증가함에 따라, 효율적인 키 관리의 필요성도 함께 증가하고 있다. 이에 본 고에서는 키 관리의 전반적인 개요와 효율적이고 안전한 키 관리를 위해 2003년도에 NIST에서 발표된 SP(Special Publication) 800-57 키 관리 가이드라인을 분석한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.3C
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• pp.220-225
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• 2002

Mobile IP aims to support mobility within the Internet. This paper concerned with the security aspect of Mobile IP. We show that current registration protocol has a possible replay attack despite the use of authenticated registration message and replay protection. We propose a public-key based registration protocol that also distributes a session-key distribution protocol in AAA. Proposed protocol provides authentication of mobile node and session-key distribution simultaneously. It also provides non-repudiation of service request.

• The Journal of Information Systems
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• v.11 no.1
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• pp.175-198
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• 2002

This paper is to develop a security module for electronic approval systems. Electronic documents are created, transmitted and saved in the company's intranet computer network. Transmitting electronic documents, however, brings us a security problem. Communications among various computer systems are exposed to many security threats. Those threats are eavesdropping, repudiation, replay back etc. The main purpose of this paper is to develop a module which provides the security of electronic documents while they are passed from one place to another This paper applies Multi-Level security to the electronic approval system that guarantees security of electronic documents from many threats. Multi-Level security controls the access to the documents by granting security level to subject users and object electronic documents. To prevent possible replay back attacks, this paper also uses one time password to the system. The security module is composed of client program and server one. The module was developed using Microsoft Visual Basic 6.0 and Microsoft SQL Server 7.0. The code uses Richard Bondi's WCCO(Wiley CryptoAPI COM Objects) library functions which enables Visual Basic to access Microsoft CryptoAPI.