• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.5C
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• pp.415-421
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• 2005

Passive RFID tag does not have its own power, so it has very poor computation abilities and it can deliver signals in very short range. From the facts, most RFID Tag security schemes assumed that the backward channel from tags to a reader is safe from eavesdropping. However, eavesdroppers near a tag can overhear message from a tag illegally. In this paper, we propose a method to protect the backward channel from eavesdropping by illegal readers. The proposed scheme can overcome the problems of conventional schemes such as randomized tree walking, which have been proposed to secure tag information in tree-walking algorithm as an anti-collision scheme for RFID tags. We showed the efficiency of our proposed method by using an analytical model, and it is also shown that the proposed method can provide the probability of eavesdropping in some standardized RFID tag system such as EPCglobal, ISO, uCode near to '0'.

• Annual Conference of KIPS
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• 2012.11a
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• pp.946-949
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• 2012

클라우드 컴퓨팅환경에서 사용되는 분산 파일 시스템은 데이터를 저장하는 분산 저장 서버와 각 데이터의 메타데이터를 저장하는 마스터 서버로 구성되어 있다. 마스터 서버와 분산 저장 서버는 수시로 서버의 상태나 메타데이터의 정보를 교환하지만, 통신 시 암호화가 전혀 고려되지 않아, 제 3자에 의한 도청이나 위변조시 사용자의 데이터에 대한 가용성을 보장받지 못할 수 있다. 이에 대한 방지 대책으로 통신 과정을 암호화함으로써 해결할 수 있지만, 무한히 확장 가능한 분산 저장서버에 대해 단일 마스터 서버와의 통신과정을 암호화하게 된다면 수많은 키에 대한 관리 대책을 필요로 하게 된다. 하지만 이 때, 분산저장서버를 하나의 그룹으로 묶어 그룹키를 사용하여 통신과정을 암호화한다면 보다 효율적으로 해결할 수 있다. 따라서 본 논문에서는 분산 저장 서버와 마스터 서버 간 안전하고 효율적인 암호화 통신을 위한 그룹키 확립 프로토콜을 제안하였다.

• Journal of Internet Computing and Services
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• v.10 no.2
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• pp.53-63
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• 2009

e-Passport system is new type of emigration and immigration control system and it is a research to introduce the e-Passport Authentication Protocol with Improved Efficiency is lively proceeded over the entire world. The e-Passport's chip has a biometric information and personal identification information, Radio Frequency Identification(RFID) technology is used for communication with the Inspection System(IS). However, the feature of the RFID system may bring about various security threats such as eavesdropping, data forgeries, data alternation, cloning, biometric data-leakage. Therefore, in this paper, we analyse the e-Passport system's authentication protocol to protect vulnerability and proposed e-Passport system's authentication protocol reduce computation. Also, we compared their efficiency.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.9 no.2
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• pp.83-92
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• 1999

Cryptography techniques can prevent eavesdroppers from maliciously intercepting or modifying sensitive information. however misuses of encryption may cause other problems First if the encryption key is lost or damaged even an authorized access to the original data will be denied. Second criminals can prevent authorized law enforcement officers from examining the necessary information by using the strong encrypted data can provide solutions for the situations. In this paper we propose a new key escrow system based on the ElGamal cryptosystem. Our system provide time-bound eavesdropping under court authorized permission protect from trustee's cheating and prevent user's shadow public key generation.

• Annual Conference of KIPS
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• 2000.10a
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• pp.141-144
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• 2000

XML은 단순함과 융통성이라는 특징을 가지고 있기 때문에 Internet B2B(Business to Business) 메세지 송수신을 용이하게 한다. Internet B2B에서 메세지 송수신을 하는 데 있어서 보안이 점차 중요하게 대두되고 있다. 인터넷은 공용 네트워크이므로 도청과 위조와 같은 공격에 어떠한 보호장치도 있지 않기 때문에 메시지가 송수신되는 동안 자신의 중요한 정보가 다른곳으로 유출되거나 손실될 경우 B2B 메시지 송수신에 있어서 크나큰 손실을 가져올 수 있다. SSL(Secure Socket Layer)은 transport-level 보안 프로토콜이 제공하는 인증, 무결성, 기밀성을 제공하고 있다. 하지만 부인방지를 제공하고 있지 못하고 있는 실정이다. 하지만 XML-Signature를 이용하면 이러한 문제점을 해결할 수 있고 프로토콜 차원이 아닌 어플리케이션 차원에서 보안 시스템을 설계하므로 B2B 간 메시지 송수신하는데 있어서 서버와 클라이언트에 각각 XML-Signature 사용하여 안전하게 통신 할 수 있도록 해주는 보안모들 설계를 소개한다.

• The KIPS Transactions:PartC
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• v.9C no.3
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• pp.343-350
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• 2002

This paper describes the implementation of H.235 protocol for authentication and media stream encryption of multimedia conference systems. H.235 protocol is recommended by ITU-T for H.323 multimedia conference security protocol to prevent from being eavesdropped and modified by an illegal attacker. The implementation in this paper has used password-based with symmetric encryption authentication. Media streams are encrypted using the Diffie-Hellman key exchange algorithm and symmetric encryption algorithms such as RC2, DES and Triple-DES. Also, 128-bit Advanced Encryption Standard and 128-bit Korean standard SEED algorithms are implemented for the future extension. The implemented authentication and media stream encryption has shown that it is possible to identify terminal users without exposing personal information on networks and to preserve security of multimedia conference. Also, encryption delay time and used memory are not increased even though supporting media stream encryption/decryption, thus the performance of multimedia conference system has not deteriorated.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.2C
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• pp.208-218
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• 2008

We are sure that RFID system should be a widely used automatic identification system because of its various advantages and applications. However, many people know that invasions of privacy in RFID system is still critical problem that makes it difficult to be used. Many works for solving this problem have focused on light-weight cryptographic functioning in the RFID tag. An agent scheme is another approach that an agent device controls communications between the tag and the reader for protecting privacy. Generally an agent device has strong security modules and enough capability to process high-level cryptographic protocols and can guarantees consumer privacy. In this paper, we present an enhanced mobile agent for RFID privacy protection. In enhanced MARP, we modified some phases of the original MARP to reduce the probability of successful eavesdropping and to reduce the number of tag's protocol participation. And back-end server can authenticate mobile agents more easily using public key cryptography in this scheme. It guarantees not only privacy protection but also preventing forgery.