• ETRI Journal
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• v.36 no.5
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• pp.856-864
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• 2014

Usually, key-establishment protocols are suggested in a security model. However, there exist several different security models in the literature defined by their respective security notions. In this paper, we study the relations between the security models of key establishment. For the chosen security models, we first show that some proven key-establishment protocols are not secure in the more restricted security models. We then suggest two compilers by which we can convert a key-establishment protocol that is secure in a specific security model into a key-establishment protocol that is still secure in a more restricted security model.

• Korean Membrane Journal
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• v.10 no.1
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• pp.8-12
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• 2008

The electrochemical properties of Nafion type membranes as a function of temperature to examine the key factors affecting the cathodic protection process at low temperatures was investigated in this study. Variable temperature experiments for AC impedance, DC resistance were conducted. The resistances of 3 Nafion membranes (N 324, N 450, N MAC) were measured in 30% KOH (aq) for a range of temperatures between $-30^{\circ}C$ and room temperature. Membrane resistance increases exponentially with decreasing temperature. This behaviour is most significant at operational temperatures below $0^{\circ}C$. These membranes are stable under the low temperature and caustic conditions of the heat exchange system, but they place a much higher restriction on the cathodic protection of the stainless heat exchange stack. N 450 has the lowest AC impedence and DC resistance at temperatures below $0^{\circ}C$ and consequently is most suitable membrane of the three, for low temperature applications.

• Genomics & Informatics
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• v.8 no.2
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• pp.94-96
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• 2010

Integrating various pathway data collections to create new biological knowledge is a challenge, for which novel computational tools play a key role. For this purpose, we developed the Java-based conversion modules KGML2SBML and KGML2BioPAX to translate KGML (KEGG Markup Language) into a couple of common data exchange formats: SBML (Systems Biology Markup Language) and BioPAX (Biological Pathway Exchange). We hope that our work will be beneficial for other Java developers when they extend their bioinformatics system into SBML- or BioPAX-aware analysis tools. This is part of our ongoing effort to develop an ultimate KEGG-based pathway enrichment analysis system.

• East Asian Economic Review
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• v.19 no.3
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• pp.275-322
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• 2015

The key objective of this study is to investigate the return and volatility spillover effects among stock market, credit default swap (CDS) market and foreign exchange market for three countries: Korea, the US and Japan. Using the trivariate VAR BEKK GARCH (1,1) model, the study finds that there are significant return and volatility spillover effects between the Korean CDS market and the Korean stock market. In addition, the return spillover effects from foreign exchange markets and the US stock market to the Korean stock market, and the volatility spillover effect from the Japanese stock market to the Korean stock market are both significant.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.760.1-762
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• 2002

키 교환 프로토콜에서 상호 인증은 필수 요소이며, 사용자에게 편리하고 비용이 적게 드는 패스워드 기반의 인증 방식이 널리 사용되고 있다. 패스워드 기반의 프로토콜은 패스워드가 가지는 제약으로 인한 공격에 대해서 안전해야 할 뿐 아니라, 사용자의 작업량을 줄이기 위한 효율성도 매우 중요한 요건이다. 본 논문에서는 서버와 사용자간의 인증을 제공하고 세션키를 공유하기 위한 키 교환 프로토콜OTP-EKE(One Time Password based Encrypted Key Exchange)를 제안한다. 키 교환을 위한 사용자 인증은 패스워드 방식을 채택하였으며, 특히 서버 디렉토리에 대한 공격 등에 대해서 안전도를 높이기 위하여 일회용 패스워드 확인자와 서버의 공개 패스워드를 이용하였다. 제안한 프로토콜은 모듈라 지수승 계산 횟수와 메시지 전송 횟수를 줄임으로써 효율성 향상을 보인다

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.7C
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• pp.1007-1014
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• 2004

In this paper, H.235 based security mechanism for H.323 multimedia applications was implemented in embedded environment. H.235 covers authentication using HMAC-SHAI -96, authenticated Diffie-Hellman key exchange, security capability exchange, session key management for voice encryption, and encryption functions such as DES, 3DES, RC2. H.235-based mechanisms were also analyzed in terms of its security and possible attacks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.5B
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• pp.833-839
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• 2010

Mobility of sensor node is one of the rising issues in Wireless Sensor Networks (WSN). However, current security researches on WSN only consider static environments. Thus they are not sufficient to be deployed in the dynamic environment where the resource is limited. In this paper, we propose the efficient node authentication and key exchange protocol that reduces the overhead in node re-authentication.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2003.07a
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• pp.126-132
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• 2003

본 논문에서는 PAK(Password-Authenticated Key Exchange)와 PAK-R 프로토콜 기반으로 세가지 형태의 MTI(Matsumoto, Takashima, Imai) 키 일치 프로토콜을 적용하여, 안전한 보안성 요구 조건을 만족하면서 다양한 시스템에 적용할 수 있는, 패스워드-인증 키 분배 프로토콜을 소개하고자 한다. PAK 패스워드-인증 키 프로토콜은 통신 주체의 짧은 길이의 패스워드를 이용하여 통신 주체의 식별 및 상호 인증 후, 크기가 긴 세션키를 분배하기 위한 프로토콜이다. 또한 PAK는 이미 안전한 보안성이 증명되었고,［8,9,10］이를 이용한 많은 패스워드 기반의 인증 키 분배 프로토콜이 소개되었다. 본 논문은 이미 안정성 검증이 된 키 분배 프로토콜을 이용하여 새로운 PAK 프로토콜을 제안하며, credential의 이용성을 보장하기 위한 다양한 응용에 적용될 수 있다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.1
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• pp.3-10
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• 2008

Since a number of password-based protocols are using human memorable passwords they are vulnerable to several kinds of password guessing attacks. In this paper, we show that two password-based key exchange and authentication protocols are insecure against off-line password-guessing attacks.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.4
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• pp.161-168
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• 2003

We discuss the security of two famous password authenticated key exchange protocols, EKE2 and PAK. We introduce ′insider assisted attack′ Based on this assumption we point out weakness of the security of EKE2 and PAK protocols. More precisely, when the legitimate user wants to find other user′s password, called "insider-assisted attacker", the attacker can find out many ephemeral secrets of the server and then after monitoring on line other legitimate user and snatching some messages, he can guess a valid password of the user using the previous information. Of course for this kind of attack there are some constraints. Here we present a full description of the attack and point out that on the formal model, one should be very careful in describing the adversary′s behavior.