• 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

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.5
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• pp.2674-2697
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• 2019

Identity authentication is a crucial line of defense for network security, and passwords are still the mainstream of identity authentication. So far trawling password attacking has been extensively studied, but the research related with personal information is always sporadic. Probabilistic context-free grammar (PCFG) and Markov chain-based models perform greatly well in trawling guessing. In this paper we propose a systematic targeted attacking model based on structure partition and string reorganization by migrating the above two models to targeted attacking, denoted as TG-SPSR. In structure partition phase, besides dividing passwords to basic structure similar to PCFG, we additionally define a trajectory-based keyboard pattern in the basic grammar and introduce index bits to accurately characterize the position of special characters. Moreover, we also construct a BiLSTM recurrent neural network classifier to characterize the behavior of password reuse and modification after defining nine kinds of modification rules. Extensive experimental results indicate that in online attacking, TG-SPSR outperforms traditional trawling attacking algorithms by average about 275%, and respectively outperforms its foremost counterparts, Personal-PCFG, TarGuess-I, by about 70% and 19%; In offline attacking, TG-SPSR outperforms traditional trawling attacking algorithms by average about 90%, outperforms Personal-PCFG and TarGuess-I by 85% and 30%, respectively.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.1
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• pp.59-69
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• 2004

Password-based authenticated group key exchange protocols provide a group of user, communicating over a public(insecure) channel and holding a common human-memorable password, with a session key to be used to construct secure multicast sessions for data integrity and confidentiality. In this paper, we present a password-based authenticated group key exchange protocol and prove the security in the random oracle model and the ideal cipher model under the intractability of the decisional Diffie-Hellman(DH) problem and computational DH problem. The protocol is scalable, i.e. constant round and with O(1) exponentiations per user, and provides forward secrecy.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.15 no.5
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• pp.73-92
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• 2005

Joux's tripartite key agreement protocol is one of the most prominent developments in the area of key agreement. Although certificate-based and ID-based authentication schemes have been proposed to provide authentication for Joux's protocol, no provably secure password-based one round tripartite key agreement protocol has been proposed yet. We propose a secure one round password-based tripartite key agreement protocol that builds on Joux's protocol and adapts PAK-EC scheme for password-based authentication, and present a proof of its security.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.117-119
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• 2021

In this paper, the strengths and weaknesses of each type of personal authentication system are examined and the development direction of the personal authentication system is presented. Currently, the personal authentication system commonly used is a text-based password system. However, most of the current text-based password systems are weak in usability and security. In order to solve this problems a personal authentication system that can replace the text-based password system is required. In this paper, we take the recently developed graphical password system as an example to find the conditions and possibilities to replace the text-based password system, and present the development direction of the personal authentication system.

• Convergence Security Journal
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• v.22 no.4
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• pp.179-188
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• 2022

Password authentication schemes (PAS) are the most common mechanisms used to ensure secure communication in open networks. Mathematical-based cryptographic authentication schemes such as factorization and discrete logarithms have been proposed and provided strong security features, but they have the disadvantage of high computational and message transmission costs required to construct passwords. Fairuz et al. therefore argued for an improved cryptographic authentication scheme based on two difficult fixed issues related to session key consent using the smart card scheme. However, in this paper, we have made clear through security analysis that Fairuz et al.'s protocol has security holes for Privileged Insider Attack, Lack of Perfect Forward Secrecy, Lack of User Anonymity, DoS Attack, Off-line Password Guessing Attack.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.34 no.1
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• pp.61-70
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• 2024

As users use various services along with the rapid increase in Internet services, it may be difficult to manage accounts. To solve these difficulties, various password management applications are emerging. From a forensic point of view, password management applications can provide clues to obtain criminal evidence. The purpose of this paper is to acquire the data stored by the user in the password management application. To this end, we propose a better way to decrypt the encrypted data through reverse engineering, evaluate the security of the application to be analyzed, and safely store the data.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.637-640
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• 2003

Authentication between Server and Client is necessary in most of Internet Service because of increasing of using of Internet. Unix-based Server upgraded security of user authentication using "Shadow Password" instead of "crypt" function. But "Shadow Password" most use same authentication method about all services. But we individually can set user authentication method using PAM(Pluggable Authentication Module). This paper will propose user authentication system using Linux-PAM that use SMART CARD as authentication token.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.9B
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• pp.931-938
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• 2009

Recently, Holbl et al. proposed an improvement to Peyravian-Jeffries's password-based authentication protocol to overcome some security flaws. However, Munilla et al. showed that Holbl et al.'s improvement is still vulnerable to off-line password guessing attack. In this paper, we provide a secure password-based authentication protocol which gets rid of the security flaws of Holbl et al.'s protocol.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10a
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• pp.503-505
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• 1998

인터넷의 빠른 성장으로 인해 E-mail은 특정 부류만의 사람이 사용하는 것이 아니라 일반 대중에게도 널리 사용되는 생활의 일부분이 되었다. 현재의 POP3 구조에서느 원격 접속을 시도할 경우 사용자의 ID와 Password는 암호화가 안된 상태로 전송된다. 이러한 것 때문에 여러 보안 공격의 대상이 될 수 있으며 여러 보안 문제를 발생시키고 있다.본 논문에서는 기존의 POP3에서 PASS라는 명령어를 통한 사용자 인증 과정에서 나타나는 무제점을 지적하고 이를 방지하기 위한 새로운 인증방법을 One-Time Password System을 이용해서 제시하고 구현하고자 한다. 또한 One-Time Password System을 이용해 불법적인 방법으로 알아낸 암호의 재사용을 방지했다. 또한 암호화 통신을 위해 관용 암호화 방식의 IDEA 알고리즘을 이용했으며, 키 분배와 관리 문제는 One-Time Password System에서 생성한 키를 IDEA의 비밀키로 사용함으로써 해결했다.