• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.2
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• pp.416-422
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• 2011

Smart grid is the next generation intelligent power grid that combines the existing electric power infrastructure and information infrastructure. It can optimize the energy efficiency in both directions, suppliers and power consumers to exchange information in real time. In smart grid environments, with existing network security threats due to the smart grid characteristics, there are additional security threats. In this paper, we propose a security mechanism that provides mutual authentication and key agreement between a remote user and the device. The proposed mechanism has some advantages that provides secure mutual authentication and key agreement and secure against a replay attack and impersonation attacks.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.5
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• pp.967-979
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• 2013

Now a day, Wireless Sensor Networks (WSNs) are being widely used in different areas one of which is healthcare services. A wireless medical sensor network senses patient's vital physiological signs through medical sensor-nodes deployed on patient's body area; and transmits these signals to devices of registered medical professionals. These sensor-nodes have low computational power and limited storage capacity. Moreover, the wireless nature of technology attracts malicious minds. Thus, proper user authentication is a prime concern before granting access to patient's sensitive and private data. Recently, P. Kumar et al. claimed to propose a strong authentication protocol for healthcare using Wireless Medical Sensor Networks (WMSN). However, we find that P. Kumar et al.'s scheme is flawed with a number of security pitfalls. Information stored inside smart card, if extracted, is enough to deceive a valid user. Adversary can not only access patient's physiological data on behalf of a valid user without knowing actual password, can also send fake/irrelevant information about patient by playing role of medical sensor-node. Besides, adversary can guess a user's password and is able to compute the session key shared between user and medical sensor-nodes. Thus, the scheme looses message confidentiality. Additionally, the scheme fails to resist insider attack and lacks user anonymity.

• Journal of Digital Convergence
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• v.15 no.10
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• pp.253-260
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• 2017

Authenticated key agreement in multi-server environments is one of very important security issues because only authorized user needs to access their data and services. To support this issue, numerous schemes have been proposed over recent years. Recently, Shin showed the security weaknesses in the previous scheme and proposed an improved scheme called SIAKAS to solve them. Unfortunately, this paper shows that SIAKAS is still weak against application server impersonation attack and could be traceable to attackers. To solve the problems in SIAKAS, we propose an untraceable authenticated key agreement scheme, denoted by UAKAS. UAKAS efficiently solves security and privacy issues in SIAKAS and the related schemes and could reduce the operation overhead at least 12% compared to them.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.2
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• pp.322-332
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• 2017

Wireless Body Area Networks is an environment that provides an appropriate service remotely by collecting user's biometric information. With the growing importance of sensor, WBAN also attracts extensive attention. Since WBAN is representatively used in the medical field, it can be directly related to the patient's life. Hence security is very important in WBAN. Mutual authentication between the client and the application provider is essential. And efficiency is also important because a used device is limited to computation cost. In this reason, ID-based anonymous authentication scheme in WBAN has been intensively studied. We show that the recent research result of Wu et al. which is about the ID-based anonymous authentication scheme is vulnerable to impersonation attack. And we propose a new ID-based anonymous authentication scheme that is secure against the attacks discovered in the existing schemes. Compared to the existing schemes, the computation cost of our scheme is improved by 30.6% and 7.3%.

• 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.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.12
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• pp.1945-1955
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• 1993

Two types of key distribution protocols with user authentication are proposed for PCS(Personal Communication Service) and digital mobile communication systems. In this paper, we investigate the service procedure and security requirement for PCS. also discuss the security problems of KDPs previously proposed for digital mobile communication, and show that Park`s type II among the schemes is easily broken by an impersonation attack. Our proposed I, II are based on the modified cryptosystem of Rabin and ElGamal, and reduce the amount of computation for user authentication. Such a reduction is good solution coped with the limited capability of user terminal on PCS. As a result of making a comparison between our schemes and the previously presented schemes, we can know ours are more secure and efficient for PCS.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.6
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• pp.1131-1141
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• 2013

Most of the single server model of cloud computing services have problems that are hard to solve, such as a service availability, insider attack, and vendor lock-in, etc. To solve these problems, the research about multicloud has emerged. Multicloud model can supplement previous cloud model's weakness and provides new services to user. In this paper, we focus on a user authentication problem in multicloud model and propose a scheme to resolve it. We define a cloud broker-based multicloud model. And we propose an authentication protocol that is applicable at presented model. The proposed scheme can provide service transparency to user and prevent an impersonation attack by service provider.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.2
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• pp.978-1002
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• 2019

With the rapid development of the Internet of Things, the problem of privacy protection has been paid great attention. Recently, Nikooghadam et al. pointed out that Kumari et al.'s protocol can neither resist off-line guessing attack nor preserve user anonymity. Moreover, the authors also proposed an authentication supportive session initial protocol, claiming to resist various vulnerability attacks. Unfortunately, this paper proves that the authentication protocols of Kumari et al. and Nikooghadam et al. have neither the ability to preserve perfect forward secrecy nor the ability to resist key-compromise impersonation attack. In order to remedy such flaws in their protocols, we design a lightweight authentication protocol using elliptic curve cryptography. By way of informal security analysis, it is shown that the proposed protocol can both resist a variety of attacks and provide more security. Afterward, it is also proved that the protocol is resistant against active and passive attacks under Dolev-Yao model by means of Burrows-Abadi-Needham logic (BAN-Logic), and fulfills mutual authentication using Automated Validation of Internet Security Protocols and Applications (AVISPA) software. Subsequently, we compare the protocol with the related scheme in terms of computational complexity and security. The comparative analytics witness that the proposed protocol is more suitable for practical application scenarios.

• 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.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.3
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• pp.1273-1288
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• 2016

With the swift growth of wireless technologies, an increasing number of users rely on the mobile services which can exchange information in mobile networks. Security is of key issue when a user tries to access those services in this network environment. Many authentication schemes have been presented with the purpose of authenticating entities and wishing to communicate securely. Recently, Chou et al. and Farash-Attari presented two ID authentication schemes. They both claimed that their scheme could withstand various attacks. However, we find that the two authentication schemes are vulnerable to trace attack while having a problem of clock synchronization. Additionally, we show that Farash-Attari's scheme is still susceptible to key-compromise impersonation attack. Therefore, we present an enhanced scheme to remedy the security weaknesses which are troubled in these schemes. We also demonstrate the completeness of the enhanced scheme through the Burrow-Abadi-Needham (BAN) logic. Security analysis shows that our scheme prevents the drawbacks found in the two authentication schemes while supporting better secure attributes. In addition, our scheme owns low computation overheads compared with other related schemes. As a result, our enhanced scheme seems to be more practical and suitable for resource-constrained mobile devices in mobile networks.