• Journal of the Korea Society of Computer and Information
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• v.14 no.3
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• pp.133-138
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• 2009

Recently Lin et al. 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 showed that he can get the user's password using the off-line password guessing attack on the scheme when the adversary steals the user's smart card and extracts the information in the smart card. Also, we proposed the seven security requirements for evaluating remote user authentication schemes using smart card. As a result of analysis, in Lin et al's scheme we have found the deficiencies of security requirements. So we suggest the improved scheme, the mutual authentication scheme that does not store the user's password verifier in server and can authenticate each other at the same time between the user and server.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.4
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• pp.207-215
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• 2014

Password based authentication systems are most widely used for user convenience in web services. However such authentication systems are known to be vulnerable to various attacks such as password guessing attack, dictionary attack and key logging attack. Besides, many of the web systems just provide user authentication in a one-way fashion such that web clients cannot verify the authenticity of the web server to which they set access and give passwords. Therefore, it is too difficult to protect against DNS spoofing, phishing and pharming attacks. To cope with the security threats, web system adopts several enhanced schemes utilizing one time password (OTP) or long and strong passwords including special characters. However there are still practical issues. Users are required to buy OTP devices and strong passwords are less convenient to use. Above all, one-way authentication schemes generate several vulnerabilities. To solve the problems, we propose a multi-channel, multi-factor authentication scheme by utilizing QR-Code. The proposed scheme supports both user and server authentications mutually, thereby protecting against attacks such as phishing and pharming attacks. Also, the proposed scheme makes use of a portable smart device as a OTP generator so that the system is convenient and secure against traditional password attacks.

• Journal of the Korea Society of Computer and Information
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• v.26 no.9
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• pp.89-96
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• 2021

In this paper, we analyzed that the user authentication scheme for TMIS(Telecare Medicine Information System) proposed by Al-Saggaf et al. In 2019, Al-Saggaf et al. proposed authentication scheme using biometric information, Al-Saggaf et al. claimed that their authentication scheme provides high security against various attacks along with very low computational cost. However in this paper after analyzing Al-Saggaf et al's authentication scheme, the Al-Saggaf et al's one are missing random number s from the DB to calculate the identity of the user from the server, and there is a design error in the authentication scheme due to the lack of delivery method. Al-Saggaf et al also claimed that their authentication scheme were safe against a variety of attacks, but were vulnerable to password guessing attack using login request messages and smart cards, session key exposure and insider attack. An attacker could also use a password to decrypt the stored user's biometric information by encrypting the DB with a password. Exposure of biometric information is a very serious breach of the user's privacy, which could allow an attacker to succeed in the user impersonation. Furthermore, Al-Saggaf et al's authentication schemes are vulnerable to identity guessing attack, which, unlike what they claimed, do not provide significant user anonymity in TMIS.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05b
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• pp.733-738
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• 2004

In a distributed network system, Kerberos certification mechanism is operated by a user in local area on the premise reliability of Kerberos server in another area. But it has a demerit. If security information of certification server between Kerberos servers is released, Kerberos server can not guarantee the reliability. To solve this problem, the proposed mechanism prevents password speculating attack by increasing the random of password certifier through use of distributed password in stead of certification center and certification which was presented by existing Kerberos mechanism. Besides, it used password based certification method which uses secret distributed technique

• Review of KIISC
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• v.17 no.3
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• pp.12-17
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• 2007

최근 인터넷과 같은 통신 기술이 급속도로 발전함에 따라, 많은 서비스들이 온라인을 통해서 이루어지고 있다. 그러나 인터넷은 개방형 네트워크이기 때문에 공격자에 의한 시스템 침입, 도청 돈과 같은 여러 공격이 쉽게 발생된다. 특히 기존에 오프라인 상에서 이루어지던 은행 거래와 상거래가 인터넷 뱅킹과 전자상거래와 같이 온라인상에서 이루어짐에 따라 그 위험 수준은 더욱 높아지고 있다. 이러한 환경에서 사용자 인증은 안전한 통신을 위한 필수적인 요소라 할 수 있다. 대표적인 인증 방법으로 ID/Password 방식이 사용된다 하지만 ID/Password의 경우 추측이나 도청에 의해 쉽게 공격될 수 있는 단점을 가지고 있다. 이러한 단점을 극복할 수 있는 인증 기법이 매번 새로운 패스워드를 생성하는 일회용 패스워드(OTP: One-Time Password) 기술을 활용한 인증 방법이다. 본 논문에서는 이러한 OTP 기술 분석 및 표준화 동향에 대해 소개하고자 한다.

• Journal of KIISE:Information Networking
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• v.31 no.4
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• pp.347-352
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• 2004

In this paper, we propose a new key exchange protocol which authenticates each other and shares a session key between a user and a server over an insecure channel using only a small password. The security of the protocol is based on the difficulty of solving the discrete logarithm problem and the Diffie-Hellman problem and the cryptographic strength of hash function. The protocol is secure against the man-in-the-middle attack, the password guessing attack, the Denning-Sacco attack, and the stolen-verifier attack, and provide the perfect forward secrecy. Furthermore, it is more efficient than other well-known protocols in terms of protocol execution time because it could be executed in parallel and has a simple structure.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.4 no.3
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• pp.182-188
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• 2011

Recently Yoon et al. proposed the remote user authentication scheme using smart cards. But their scheme has not satisfied security requirements which should be considered in the user authentication scheme using the password based smart card. In this paper, we prove that Yoon et al.'s scheme is vulnerable to a password guessing attack in case that the attacker steals the user's smart card and extracts the information from the smart card. Accordingly, this paper proposes the improved user authentication scheme based on the hash functin and random nonce that can withstand various possible attacks including a password guessing attack. The result of comparative analysis demonstrates that the proposed scheme is more secure and efficient than Yoon et al.'s scheme, with a trivial trade-off to require just a few more exclusive-OR operations.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.16 no.6
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• pp.73-80
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• 2006

Recently, Sun et el. proposed a three-party authenticated key exchange protocol using the public key of the server and the derived verifier from the Password of a user. This paper proposes a password-based three-party authenticated key exchange protocol using smartcards. Since the proposed protocol has very low computation cost by using XOR and hash function operation instead of the public key operation, and reduces the count of message transmission to 20% compared with the protocol of Sun et el., it can execute an effective authenticated key exchange. Furthermore, the proposed protocol is safe from password guessing attack by not saving passwords in the server, and it is also safe from server compromise attack because the server cannot know the shared session key between the two users.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10a
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• pp.784-786
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• 2003

패스워드 기반 키 교환 프로토콜은 참여자들이 쉽게 기억할 수 있는 자신의 패스워드를 사용하므로 단순성, 편리성, 이동성의 장점 때문에 광범위하게 사용된다. 2000년에 Lin, Sun, Hwang［1］이 Steiner, Tsudik, Waidner［2］가 제안한 three-party EKE 프로토콜(STW-3PEKE)이 패스워드 추측 공격에 취약함을 증명하고 이를 개선한 서버의 공개키를 이용한 새로운 three-party EKE 프로토콜(LSH-3PEKE)을 제안했다. 2001년에는 Lin, Sun, Steiner, Hwang［3］이 서버의 공개키를 사용하지 않는 새로운 three-party EKE 프로토콜(LSSH-3PEKE)을 제안했다. 본 논문에서는 검증자(verifier) 기반 즉 서버가 사용자의 패스워드를 저장하지 않고 패스워드에 의해 생성되는 검증자를 가지는 프로토콜을 제안하며 이전에 제안한 프로토콜의 안전성을 그대로 유지하면서 좀 더 간단하며 효율적인 프로토콜을 제시한다.

• Journal of the Korea Society of Computer and Information
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• v.10 no.3 s.35
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• pp.133-141
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• 2005

Digital contents can be distributed via internet without qualify defect and this will bring a great loss to the contents provider. Therefore, it is necessary to investigate on the key exchanging protocol to protect the digital contents effectively. In this study we propose the key exchanging protocol based on password to send the digital contents efficiently. The stability suggested here is based on the difficulty of the discrete algebra and Diffie-Hellman problem and also it provides a secure safety against various attacks such as a guess attack on the password.