• The Journal of the Korea Contents Association
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• v.15 no.11
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• pp.501-508
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• 2015

Most web sites, information systems use the ID/Password technique to identify and authenticate users. But ID/Password technique is vulnerable to security. The user must remember the ID/Password and, the password should include alphabets, numbers, and special characters, not to be predicted easily. User also needs to change your password periodically. In this paper, we propose the user authentication method that the user authentication information stored in the external storage to authenticate a user. If another person knows the ID/Password, he can't log in a system without the external storage. Whenever a user logs in a system, authentication information is generated, and is stored in the external storage. Therefore, the proposed user authentication method is the traditional ID/Password security technique, but it enhances security and, increases user convenience.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.2
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• pp.189-200
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• 2012

With increasing the number of smart device such as Tablet PC, smart phone and netbook, information security which based on smart device in mobile environment have become the issue. It is important to enter a password safety. In various types of mobile devices, because of hardware limitation of device, it is difficult that to equip secondary input device such as keyboard and mouse. Also, a loss of accuracy becomes a problem because input information was entered by touch screen. Because of problem mentioned above it can be predicted to change password scheme text based password scheme to graphical password scheme, graphical password scheme is easy to use and is resistant to shoulder surfing attack. So this paper proposes new graphical password scheme based 5 strokes which are made by decomposed the Korean to defend against shoulder surfing attack.

• The Journal of the Korea Contents Association
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• v.17 no.7
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• pp.276-282
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• 2017

Password-based authentication is vulnerable because of its low cost and convenience, but it is still widely used. In order to increase the security of the password-based user authentication method, the password is changed frequently, and it is recommended to use a combination of numbers, alphabets and special characters when generating the password. However, it is difficult for users to remember passwords that are difficult to create and it is not easy to change passwords periodically. Therefore, in this paper, we implemented a user authentication system that does not require a password by using the USB memory that is commonly used. Authentication data used for authentication is protected by USB data stored in USB memory using USB device information to improve security. Also, the authentication data is one-time and reusable.Based on this, it is possible to have the same security as the password authentication system and the security level such as certificate or fingerprint recognition.

• Journal of Digital Contents Society
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• v.14 no.2
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• pp.179-189
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• 2013

With the rapid development of information technology in 21st century, networks are being used with various devices. Most human actions are processed through cyber space, and it is no longer separate from daily life; it has changed into one of the most important aspects of human life. Unfortunately, in cyber space, certification method has not only technical problems, but also ethological problems. Many users seemed to use the same password throughout several sites. And for a long period they refused to change it or made a small change from the earlier password. This research aims to discuss general factors of choosing and using passwords within information security through statistical analysis.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.1
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• pp.27-38
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• 2003

Most password-authenticated key exchange schemes in the literature provide an authenticated key exchange between a client and a server based on a pre-shared password. With a rapid change in modem communication environments, it is necessary to construct a secure end-to-end channel between clients, which is a quite different paradigm from the existing ones. In this paper we propose a new framework which provides a password-authenticated ky exchange between clients based only on their two different Passwords without my Pre-shared secret, so called Client-to-Client Password-Authenticated Key Exchange(C2C-PAKE). Security notions and types of possible attacks are newly defined according to the new framework We prove our scheme is secure against all types of attacks considered in the paper. Two secure C2C-PAKE schemes are suggested, one in a cross-realm setting and the other in a single-sorrel setting.

• International Journal of Internet, Broadcasting and Communication
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• v.8 no.3
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• pp.41-49
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• 2016

Recently, many biometrics-based user authentication schemes for telecare medicine information systems (TMIS) have been proposed to improve the security problems in user authentication system. In 2014, Mishra et al. proposed an improvement of Awasthi-Srivastava's biometric based authentication for TMIS which is secure against the various attacks and provide mutual authentication, efficient password change. In this paper, we discuss the security of Mishra et al.'s authentication scheme, and we have shown that Mishra et al.'s authentication scheme is still insecure against the various attacks. Also, we proposed the improved scheme to remove these security problems of Mishra et al.'s authentication scheme, even if the secret information stored in the smart card is revealed. As a result, we can see that the improved biometric based authentication scheme is secure against the insider attack, the password guessing attack, the user impersonation attack, the server masquerading attack and provides mutual authentication between the user and the telecare system.

• KIPS Transactions on Computer and Communication Systems
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• v.9 no.7
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• pp.149-156
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• 2020

All operating systems have privileged administrator accounts for efficient management. Dangerous or sensitive tasks or resources should be banned from normal users and should only be accessible by administrators. One example of this privilege is to reset a user's password when the user loses his/her password. In this paper, the privileges of the sudoer group, the administrator group of Linux Ubuntu, and the management system of the sudoer group were analyzed. We show the danger that a sudoer can use the privilege to change the password of other users, including other sudoers, and modify the log, and suggest a countermeasure to prevent the manipulation of shadow files as a solution to this. In addition, the proposed method was implemented and the possibility of practical use was confirmed with excellent performance.

• The Journal of the Korea Contents Association
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• v.17 no.7
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• pp.571-578
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• 2017

In order to approach information system through smart device and pc, user has to authenticate him or herself via user authentication. At that time when user tries reaching the system, well-used user authentication technologies are ID/PW base, OTP, certificate, security card, fingerprint, etc. The ID/PWbased method is familiar to users, however, it is vulnerable to brute force cracking, keylogging, dictionary attack. so as to protect these attacks, user has to change the passwords periodically as per password combination instructions. In this paper, we designed and implemented a user authentication system using smartphone's USIM without using password while enhancing security than existing ID / PW based authentication technology.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.10
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• pp.2750-2759
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• 2009

In this paper, we analyze vulnerabilities in a remote authentication protocol using smartcards which was proposed by Bindu et al. and propose an improved scheme. The proposed scheme can prevent from restricted replay attack and denial of service attack by replacing time stamp with random number. In addition, this protocol can guarantee user anonymity by transmitting encrypted user's ID using AES cipher algorithm. The computational load in our protocol is decreased by removing heavy exponentiation operations and user efficiency is enhanced due to addition of password change phase in which a user can freely change his password. Furthermore, we really implement the proposed authentication protocol using a STM smartcard and authentication server. Then we prove the correctness and effectiveness of the proposed remote authentication system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.8C
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• pp.697-702
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• 2012

In 2011, C.-T. Li et al. proposed a secure user authentication scheme, which is an improvement over Kim et al.'s scheme to resolve several security flaws such as off-line password guessing attack and masquerading attack. C.-T. Li et al. claimed that their scheme prevents smart card security related attacks. Moreover, it provides mutual authentication and session key establishment. However, we found that their scheme is vulnerable to password guessing attack through password change phase, smart card forgery attack and stolen verifier attack. Moreover, C.-T. Li et al.'s scheme is not secure against password guessing attack as they claimed. In this paper, we also point out that their scheme is not practical to use.