• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.6
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• pp.95-101
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• 2016

With the rapid development of Internet and communication network technology, various studies had proceeded to develop the technology of wireless sensor networks. Authentication schemes for user and sensor are critical and important security issue to use wireless sensors legally. First, Das introduce a user authentication scheme using smart card and password for wireless sensor networks, various studies had proceeded. Chem et al. suggested a secure user authentication scheme against smart card loss attack but Chen et al. scheme does not still resolve some security vulnerability such as perfect forward secrecy, session key exposure by gateway node, anonymity, and the password check. To resolve the problems, this paper proposes a security enhanced user authentication using the fuzzy extraction, elliptic curves cryptography and dynamic ID and analyzes the security.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.4B
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• pp.226-234
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• 2005

Context-Aware is the most important facts to reason a personalized and optimized service and to provide it to user. In the previous researches, user and surrounding environment were main facts of Context-Aware and middleware or center server has been proposed to support Context-Aware. In the daily space(for example, home, office, Car, etc), interactions between user and service can be a important facts of Context-Aware. In this paper, Context Autogenesis service model is introduced, simplified the Context-Aware process and designed the middleware which performs decentralize management for Context-Aware information of user's portable devices, so that problems occurred during the management and operation of existing Context-Aware system can be minimized and supporting user anonymity

• Journal of the Korea Society of Computer and Information
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• v.29 no.6
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• pp.53-60
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• 2024

In this paper, we analyze the authentication scheme of Hwang et al. proposed in 2023 and propose a new authentication scheme that improves its problems. Hwang et al. claimed that their authentication scheme was practical and secure, but as a result of analysis in this paper, it is possible to attack the password/ID guessing attack and session key disclosure attack due to insider attack and stolen smart card attack. In addition, Hwang et al.'s authentication scheme, which provides user anonymity, does not provide user untraceability due to its unstable design. The proposed authentication scheme, which improves these problems, not only provides user untraceability, but also is secure for stolen smart card attack, insider attack, session key disclosure attack, and replay attack. In addition, except for one fuzzy extraction operation, it shows the same complexity or very similar one as related authentication schemes. Therefore, the proposed authentication scheme can be said to be an authentication scheme with safety and practicality.

• The Transactions of the Korea Information Processing Society
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• v.5 no.11
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• pp.2921-2929
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• 1998

We propose an efficient off-line electronic cash system based on the certificate issued by Certificate Authority. It satisfies all the basic requirements for electronic payment system such as cash unforgeability, cash anonymity, double spending detection, no framing, etc. Our proposed system is very computationally efficient in the sense that: (1) the number of exponentiation operation imposed on the user during withdrawal phase is much smaller than any existing off-line electronic cash schemes, (2) all the computation of user's during withdrawal phase can be performed by off-line pre-processing. So the proposed system is suitable to be implemented by smart cards in both memory and computation.

• IEIE Transactions on Smart Processing and Computing
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• v.2 no.2
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• pp.57-66
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• 2013

Wireless Sensor Networks consist of small, inexpensive, low-powered sensor nodes that communicate with each other. To achieve a low communication cost in a resource constrained network, a novel concept of signcryption has been applied for secure communication. Signcryption enables a user to perform a digital signature for providing authenticity and public key encryption for providing message confidentiality simultaneously in a single logical step with a lower cost than that of the sign-then-encrypt approach. Ring signcryption maintains the signer's privacy, which is lacking in normal signcryption schemes. Signcryption can provide confidentiality and authenticity without revealing the user's identity of the ring. This paper presents the security notions and an evaluation of an ID-based ring signcryption scheme for wireless sensor networks. The scheme has been proven to be better than the existing schemes. The proposed scheme was found to be secure against adaptive chosen ciphertext ring attacks (IND-IDRSC-CCA2) and secure against an existential forgery for adaptive chosen message attacks (EF-IDRSC-ACMA). The proposed scheme was found to be more efficient than scheme for Wireless Sensor Networks reported by Qi. et al. based on the running time and energy consumption.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.12
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• pp.2193-2201
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• 2006

In related to mobile communication environment. Kesdogan and Pfitzmann[1,2,3] proposed solutions using temporary pseudonym identification, called TP(Temporary Pseudonym) to solve the problems concerning current locations of mobile users and exposure of their movements in the privacy aspect. After that, we proposed more improved method protecting mobile users from active attacks of network providers in [4]. But it is the case that mobile users are located in only home domain. As a more extended method. we propose new mobile terminated protocol protecting user privacy in case of moving from the home domain to the remote domain and analyze its security.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.7
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• pp.2719-2735
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• 2015

In the cloud environment, users pay more attentions to their data security since all of them are stored in the cloud server. Researchers have proposed many mutual authentication schemes for the access control of the cloud server by using the smart card to protect the sensitive data. However, few of them can resist from the smart card lost problem and provide both of the forward security and the backward security. In this paper, we propose a novel authentication scheme for cloud computing which can address these problems and also provide the anonymity for the user. The trick we use is using the password, the smart card and the public key technique to protect the processes of the user's authentication and key exchange. Under the Elliptic Curve Diffie-Hellman (ECDH) assumption, it is provably secure in the random oracle model. Compared with the existing smart card based authentication schemes in the cloud computing, the proposed scheme can provide better security degree.

• Journal of KIISE:Information Networking
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• v.30 no.6
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• pp.720-728
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• 2003

Blind signature is such a signature scheme that conceals the contents of signature itself and who is the user of the signature make user's anonymity possible. For this reason, they are used in security services such as electronic cashes and electronic votes in which the behavior of actor should not be exposed. In this paper we propose an ID-based blind signature scheme from Gap Diffie-Hellman group. Its security is based on the hardness of Computational Diffie-Hellman Problem. Proposed scheme efficiently improve against existing blind signature scheme by using two-pass protocol between two users and by reducing computation process. Therefore it can be used efficiently in wireless PKI environment.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.2
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• pp.335-343
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• 2014

It is more important to ensure the credibility of internet media which influence the public opinion. However, there are vague suspicions in public from the examples of manipulation of online reviews with anonymity. In this study, we explore the possibility of manipulating public opinion in online web sites. We investigate the characteristics of comments posted by users on web sites and compare each comments by using the cosine similarity function. Our result shows followings. First, we found a correlation between the similarities of comments and the article ranks in the web sites. Second, it is possible to identify abnormal user activities indicating excessive multiple posting, double posting and astroturf activities.

• Journal of Korea Society of Digital Industry and Information Management
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• v.14 no.4
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• pp.125-134
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• 2018

Lamport firstly suggested password base authentication scheme and then, similar authentication schemes have been studied. Due to the development of Internet network technology, remote user authentication using smart card has been studied. Li et al. analyzed authentication scheme of Chen et al. and then, Li et al. found out the security weakness of Chen et al.'s scheme such forward secrecy and the wrong password login problem, and proposed an a new smart card based user password authentication scheme. But Liu et al. found out that Li et al.'s scheme still had security problems such an insider attack and man-in-the-middle attack and then Liu et al. proposed an efficient and secure smart card based password authentication scheme. This paper analyzed Liu et al.'s authentication and found out that Liu et al.'s authentication has security weakness such as no perfect forward secrecy, off-line password guessing attack, smart-card loss attack, and no anonymity. And then, this paper proposed security enhanced efficient smart card based password authentication scheme using fuzzy extraction technology.