• Journal of information and communication convergence engineering
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• v.9 no.4
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• pp.431-434
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• 2011

Password-based user-authentication schemes have been widely used when users access a server to avail internet services. Multiserver password-authentication schemes enable remote users to obtain service from multiple servers without separately registering with each server. In 2008, Jia-Lun Tsai proposed an improved and efficient password-authenticated key agreement scheme for a multiserver architecture based on Chang-Lee's scheme proposed in 2004. However, we found that Tsai's scheme does not provide forward secrecy and is weak to insider impersonation and denial of service attacks. In this article, we describe the drawbacks of Tsai's scheme and provide a countermeasure to satisfy the forward secrecy property.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.5
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• pp.37-43
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• 2002

This paper proposes a password-based mutual authentication and key agreement protocol, which is designed by applying ECDSA and ECDH. The proposed protocol, AKE-ECC, computes 2 times of point multiplication over ECC on each of client and server, and generates the key pairs(public key. private key) and a common session key using ECDH that is different compare to previously proposed protocol. It is against common attacks include a dictionary attack and the security of proposed protocol is based on the ECDLP, ECDH.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.3
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• pp.137-144
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• 2004

3GPP(3rd Generation Project Partnership)-WLAN(Wireless Local Area Network) interworking refers to the utilization of resources and access to services within the 3GPP system by the WLAN UE(User Equipment) and user respectively. The intent of 3GPP-WLAN Interworking is to extend 3GPP services and functionality to the WALN access environment. We propose an efficient mechanism for the setup of UE-initiated tunnels in 3GPP-WLAN interworking. The proposed mechanism is based on a secret key which is pre-distributed in the process of authentication and key agreement between UE and 3GPP AAA(Authentication, Authorization Accounting) server. Therefore it can avoid modular exponentiation and public key signature which need a large amount of computation in UE. Also the proposed scheme provides mutual authentication and session key establishment between UE and PDGW(Packet Data Gateway).

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.7
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• pp.3678-3698
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• 2017

With the rapid development of vehicular ad hoc Network (VANET), it has gained significant popularity and received increasing attentions from both academics and industry communities in aspects of security and efficiency. To address the security and efficiency issues, a self-authentication and deniable efficient group key agreement protocol is proposed in this paper. The scheme establishes a group between road side units (RSUs) and vehicles by using self-authentication without certification authority, and improves certification efficiency by using group key (GK) transmission method. At the same time, to avoid the attacker attacking the legal vehicle by RSUs, we adopt deniable group key agreement method to negotiation session key (sk) and use it to transmit GK between RSUs. In addition, vehicles not only broadcast messages to other vehicles, but also communicate with other members in the same group. Therefore, group communication is necessary in VANET. Finally, the performance analysis shows superiority of our scheme in security problems, meanwhile the verification delay, transmission overheard and message delay get significant improvement than other related schemes.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.3
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• pp.49-59
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• 2002

As the electronic commerce increases rapidly in the mobile communication, security issues become more important. A suitable authentication and key agreement for the mobile communication environment is a essential condition. Some protocols based on the public key cryptosystem such as Diffie-Hellman, EIGamal etc. were adapted in the mobile communication. But these protocols that are based on the difficult mathematical problem in the algebra, are so slow and have long key-length. Therefore, these have many limitation to apply to the mobile communication. In this paper, we propose an authentication and key agreement protocol based on NTRU to overcome the restriction of the mobile communication environment such as limited sources. low computational fewer, and narrow bandwidth. The proposed protocol is faster than other protocols based on ECC, because of addition and shift operation with small numbers in the truncated polynomial ring. And it is as secure as other existent mathematical problem because it is based on finding the Shortest or Closest Vector Problem(SVP/CVP).

• IEMEK Journal of Embedded Systems and Applications
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• v.5 no.3
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• pp.168-174
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• 2010

User authentication is an important requirement to provide secure network service. Therefore, many authentication schemes have been proposed to provide secure authentication, such as key agreement and anonymity. However, authority of scheme is limited to one's self. It is inefficient when authenticated users grant a certification to other users who are in an organization which has a hierarchical structure, such as a company or school. In this paper, we propose the first authentication scheme to use Attributes-Based Re-encryption that creates a certification to other users with specified attributes. The scheme, which has expanded from Rhee et al. scheme, has optimized computation performance on a smart card, ensuring the user's anonymity and key agreement between users and server.

• Journal of Korea Society of Digital Industry and Information Management
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• v.5 no.4
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• pp.139-150
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• 2009

Authentication and key exchange are fundamental for establishing secure communication channels over public insecure networks. Password-based protocols for authenticated key exchange are designed to work even when user authentication is done via the use of passwords drawn from a small known set of values. There have been many protocols proposed over the years for password authenticated key exchange in the three-party scenario, in which two clients attempt to establish a secret key interacting with one same authentication server. However, little has been done for password authenticated key exchange in the more general and realistic four-party setting, where two clients trying to establish a secret key are registered with different authentication servers. In fact, the recent protocol by Yeh and Sun seems to be the only password authenticated key exchange protocol in the four-party setting. But, the Yeh-Sun protocol adopts the so called "hybrid model", in which each client needs not only to remember a password shared with the server but also to store and manage the server's public key. In some sense, this hybrid approach obviates the reason for considering password authenticated protocols in the first place; it is difficult for humans to securely manage long cryptographic keys. In this work, we introduce a key agreement protocol and a key distribution protocol, respectively, that requires each client only to remember a password shared with its authentication server.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2003.07a
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• pp.47-50
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• 2003

본 논문에서는 DH(Diffie-Hellman) 기반의 사용자 인증 및 키 교환 프로토콜인 SAK(Simple Authentication and Key-agreement)를 제안하고자 한다. 제안 프로토콜 SAK는 단순하고 사용하기 쉬운 패스워드와 이산 대수 문제의 어려움을 이용하여 안전하고 효율적이다. 패스워드 기반 프로토콜의 취약점인 사전 공격(Dictionary attack)과 알려진 공격으로부터 안전하고 DH 기반의 기존 프로토콜보다 적은 지수 계산량을 요구한다.

• Journal of information and communication convergence engineering
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• v.7 no.3
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• pp.340-344
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• 2009

Multi-server password authentication schemes enable remote users to obtain service from multiple servers with single password without separately registering to each server. In 2007, Hu-Niu-Yang proposed an improved efficient password authenticated key agreement scheme for multi-server architecture based on Chang-Lee's scheme proposed in 2004. This scheme is claimed to be more efficient and is able to overcome a few existing deficiencies in Chang-Lee's scheme. However, we find false claim of forward secrecy property and some potential threats such as offline dictionary attack, key-compromise attack, and poor reparability in their scheme. In this paper, we will discuss these issues in depth.

• The Transactions of the Korea Information Processing Society
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• v.6 no.12
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• pp.3613-3621
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• 1999

In this paper, we analyzed the suity of key distribution protocol based on discrete logarithm for the purpose of designing key distribution protocol systematically. We also propose the efficient key agreement protocol with direct authentication. In comparison with Station-to-Station protocol, it provides the direct authentication using the Diffie-Hellman problem without signature.