• Proceedings of the Korea Information Processing Society Conference
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• 2005.05a
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• pp.1213-1216
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• 2005

인터넷을 통한 자동화된 업무가 증가함에 따라서, 공공 컴퓨터들에 대한 의존도가 높아지고 있다. 그러나 오늘날 웹메일, 옥션, 인터넷 뱅킹, 휴대폰 결제등과 같은 위한 원격 서비스들은 사용자의 신원을 증명하기 위해 사용자의 아이디와 패스워드 또는 주민등록번호를 요구한다. 하지만 안전하지 못한 채널로 전송되는 사용자의 정보는 공격자에 의해서 도청및 재사용될 가능성이 매우 높다. 본 논문에서는 위와 같이 보안이 취약한 환경에서 안전한 사용자 인증이 성공적으로 이루어 질 수 있는 새로운 인증 시스템을 제안하고자 한다. 제안 시스템은 현대의 일반 사용자들이 항상 소지하는 휴대폰의 SMS(Simple Message Service)와 일회용 패스워드(OTP : One Time Password)를 기반으로 한다.

• Journal of the Korea Society of Computer and Information
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• v.16 no.2
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• pp.183-191
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• 2011

Recently Wang-Li proposed the remote user authentication scheme using smart cards. But the proposed scheme has not been satisfied security requirements considering in the user authentication scheme using the password based smart card. In this paper, we described the Wang-Li and Yoon et al.'s authentication scheme simply, and we prove that the Wang-Li's scheme is vulnerable to a password guessing attack and impersonation attack in case that the attacker steals the user's smart card and extracts the information in the smart card. Accordingly, we propose the improved user authentication scheme based on the hash function and generalized ElGamal signature scheme that can withstand many possible attacks including a password guessing attack, impersonation attack and replay attack, and that can offer the function of forward secrecy. The result of comparative analysis, the our proposed scheme is much more secure and efficient than the Wang-Li and Yoon et al.'s scheme.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.1
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• pp.231-237
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• 2012

In 2011, Das proposed an effective biometrics-based remote user authentication scheme using smart cards that can provide strong authentication and mutual authentication, while eliminating the security drawbacks of Li-Hwang's scheme. In this paper, we have shown that Das's scheme is still insecure against several attacks and does not provide mutual authentication. Also, we proposed the enhanced scheme to overcome these security weaknesses, even if the secret information stored in the smart card is revealed. As a result of security analysis, the enhanced scheme is secure against user impersonation attack, server masquerading attack, off-line password guessing attack, and insider attack. And we can see that the enhanced scheme provides mutual authentication between the user and the server.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.12C
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• pp.1021-1028
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• 2008

In a network environment, when a user requests a server's service, a remote user authentication system using smart cards is a very practical solution to validate the eligibility of a user and provide secure communication. In these authentication schemes, due to fast progress of networks and information technology, most of provided services are in multi-server environments. However, there are no studies in multi-server authentication schemes using smart cards providing mutual anonymity so far. In this paper, we propose a novel user authentication scheme using smart cards providing mutual authentication and mutual anonymity for multi-server environments. Our proposed scheme achieves the low-computation requirement for smart cards and a user can use permitted various services in eligible servers by only one registration. Also, this scheme guarantees perfect mutual anonymity of participants.

• Journal of the Korea Society of Computer and Information
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• v.15 no.1
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• pp.139-147
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• 2010

A remote user authentication scheme is a two-party protocol whereby an authentication server in a distributed system confirms the identity of a remote individual logging on to the server over an untrusted, open network. In 2005, Liao et al. proposed a remote user authentication scheme using a smart card, in which users can be authenticated anonymously. Recently, Yoon et al. have discovered some security flaws in Liao et al.'s authentication scheme and proposed an improved version of this scheme to fix the security flaws. In this article, we review the improved authentication scheme by Yoon et al. and provide a security analysis on the scheme. Our analysis shows that Yoon et al.'s scheme does not guarantee not only any kind of authentication, either server-to-user authentication or user-to-server authentication but also password security. The contribution of the current work is to demonstrate these by mounting two attacks, a server impersonation attack and a user impersonation attack, and an off-line dictionary attack on Yoon et al.'s scheme. In addition, we propose the enhanced authentication scheme that eliminates the security vulnerabilities of Yoon et al.'s scheme.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.4
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• pp.841-849
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• 2012

Cloud computing that provides IT service and computer resource based on internet is now getting attention. However, the encrypted data can be exposed because it is saved in cloud server, even though it is saved as an encrypted data. In this paper, user certification protocol is proposed to prevent from illegally using of secret data by others while user who locates different physical position is providing secret data safely. The proposed protocol uses one way hash function and XOR calculation to get user's certification information which is in server when any user approaches to particular server remotely. Also it solves user security problem of cloud.

• Journal of the Korea Society of Computer and Information
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• v.15 no.2
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• pp.119-125
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• 2010

Recently Hsiang-Shih proposed the user authentication scheme to improve Yoon et al's scheme. But the proposed scheme has not been satisfied security requirements considering in the user authentication scheme using the password based smart card. In this paper, we proved that Hsiang-Shih's scheme is vulnerable to the off-line password guessing attack. In other words, the attacker can get the user's password using the off-line password guessing attack on the scheme when the attacker steals the user's smart card and extracts the information in the smart card. Also, the improved scheme based on the hash function and random number was introduced, thus preventing the attacks, such as password guessing attack, forgery attack and impersonation attack etc. And we suggested the effective mutual authentication scheme that can authenticate each other at the same time between the user and server.

• Journal of Internet Computing and Services
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• v.14 no.4
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• pp.43-51
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• 2013

User authentication and access control are two important components in high security applications. Recently, Chen and Yeh proposed a method to integrate both of them seamlessly. However, Chen-Yeh's scheme is vulnerable to a stolen verifier attack, since it maintains a smart card identifier table in a remote server. Therefore, this paper modifies Chen-Yeh's scheme and propose a new integrated authentication and access control scheme that is resilient to the stolen verifier attack while inheriting all the merits of Chen-Yeh's scheme. Security analysis shows that the proposed scheme withstands well-known security attacks and exhibits many good features.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.11a
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• pp.858-861
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• 2011

Smart Society로 나아가는 핵심으로 손꼽히는 모바일의 급속한 확산은 교육, 교통, 경제뿐만 아니라 건강에도 큰 영향을 미치고 있다. 그동안 발전이 미진했던 u-Health 기술 및 시장 역시 모바일로 인해 새로운 서비스 모델을 제시함으로써 발전하고 있다. 본 논문은 제안하는 시스템은 u-Health 서비스 중 sensor를 이용하여 원격지 환자의 생체정보를 수집하고, 실시간으로 병원의 클라우드 서버에 전송하는 시스템에서 사용자 검증에 대하여 연구하였다. 여기서 사용자란 클라우드 서버에 접속하는 의사를 말하며, 환자의 생체정보를 보기 위하여 시스템 접속함에 있어 공인인증서나 기타 인증 시스템과 비교해 간편하고, 네트워크 트래픽이 적은 사용자 검증 시스템을 목표로 한다. 그리하여 QRcode를 3개 생성하고, 각 클라우드 서버에 분산 분배 후 서로 섞음으로써 기존의 QRcode와 전혀 다른 인증용 QRcode를 생성할 수 있었다. 이것을 3차원 인덱스를 통해 원본 사용자 QRcode와 대조함으로 사용자 검증 과정을 수행시킴으로써 절차를 간소화하고 네트워크 트래픽을 약 15% 감소시킬 수 있었다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.10
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• pp.4612-4617
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• 2011

Hsiang-Shin proposed a user authentication scheme which was created by improving Yoon's scheme. Afterwards, An showed the failure to meet security requirements which are considered in user authentication using password-based smart card in Hsiang-Shih-suggested scheme. In other words, it was found that an attacker can steal a user's card, and detect a user's password by temporarily accessing it and extracting the information stored in it. However, An-proposed scheme also showed its vulnerability to password-guessing attack and forgery/impersonation attack, etc. and thus, this paper proposed the improved user authentication scheme. The proposed authentication scheme can thwart the password-guessing attack completely and this paper proposed scheme also includes an efficient mutual authentication method that can make it possible for users and authentication server to certify the other party.