• Journal of KIISE:Computer Systems and Theory
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• v.29 no.3
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• pp.153-160
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• 2002

In this paper, we consider a secure and efficient metering scheme to measure the interaction between clients and servers in interned advertising. In most cases internet advertising is composed of clients, servers, and an audit agency who collects a metering information about the number of clients that were served by each server. The metering scheme should always be secure against fraud attempts by servers which maliciously try to inflate the number of their clients and against clients that attempt to disrupt the metering process. So we suggest secure and efficient metering schemes, based on some cryptographic techniques, which are also very accurate and robust.

• Proceedings of the Korea Information Processing Society Conference
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• 2006.05a
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• pp.905-908
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• 2006

MIPv6 는 MN(Mobile Node)가 자신의 홈 네트워크를 벗어나 외부 네트워크로 이동하여도 다른 노드들과 끊김 없이 지속적인 통신을 할 수 있게 해주는 인터넷 프로토콜이다. MN 은 외부네트워크로 이동 후 HA(Home Agent) 및 CN(Correspondent Node)로 핸드오버(Handover) 동작의 수행하며 이로 인한 지연이 발생하게 된다. 이러한 지연을 줄이기 위한 대책으로 Fast 핸드오버가 등장하였다. Fast 핸드오버 과정에서 MN 은 이동하려는 서브넷의 라우터(New Access Router: NAR)로의 전환을 위하여 현재 연결된 AR 과 미리 정보를 주고 받게 되고, 이동이 발생한 후에 NAR 과의 핸드오버 지연시간이 감소하게 된다. 반면 공격자가 flooding 을 통해 MN 에게 DoS(Denial of Service) 공격을 가하여 MN 을 다운시킨 후, MN 으로 위장하여 데이터를 가로채는 취약점이 존재한다. 본 논문에서는 위의 취약점을 보완하기 위하여 핸드오버 과정에서 주고받는 메세지에 대한 기밀성 및 노드 인증을 제공하는 ID 기반 암호시스템에 기반한 안전한 Fast 핸드오버 방식을 제안한다. 제안하는 모델은 메시지의 암호화와 노드 인증을 통해 무결성 및 기밀성을 보장하고 Traditional PKI 시스템에 비해 공개키 인증시간을 단축하는 이점을 가질 것으로 기대된다.

• The Transactions of the Korea Information Processing Society
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• v.4 no.6
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• pp.1565-1575
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• 1997

A new encryption algorithm had been proposed as a replacement to the Data Encryption Standard (DES) in [1,2]. It called the Extended DES (EDES) has a key length of 112 bits. The plaintext data consists of 96 bits divided into 3 sub-blocks of 32 bits each. The EDES has a potentially higher resistance to differential cryptanalysis that the DES due to the asymmetric number of f functions performed on each of the 3 sub-blocks and due to the increase of S-boxes from 8 to 16. This paper propose a hardware design for the EDES and its implementation in VLSI. The VLSI chip implements data encryption and decryption in a single hardware unit. With a system clock frequency of 15Mhz the device permits a data conversion rate of about 90Mbit/sec. Therefore, the chip can be applied to on-line encryption in high-speed networking protocols.

• Journal of Korea Multimedia Society
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• v.7 no.7
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• pp.922-933
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• 2004

In recent years, peer-to-peer network have a greate deal of attention for distributed computing or collaborative application, and work of ID-based public key systems have been focusing on the area of cryptography. In this paper, we propose ID-based group key management protocols for secure communication in autonomous peer group. Each member obtains his public/private key pair derived from his identification string from Private Key Generator. No central server participates in group key management protocol instead, all group members share the burden of group key management by the collaboration of themselves, so that our scheme avoids the single point of failure problem. In addition, our scheme considers the nature of dynamic peer group such as frequent joining and leaving of a member.

• Journal of KIISE:Computer Systems and Theory
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• v.30 no.9
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• pp.487-493
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• 2003

A secret sharing scheme is a cryptographic Protocol that a dealer distributes shares about a secret to many participants and authorized subsets of the participants can reconstruct the secret. Secret sharing schemes that reflect various access structure were proposed. We propose a new reusable secret sharing scheme in a hierarchical group. Participants have priority about restoration of secret from high position level of tree. And when participants who belong in high position level are absent, they can delegate restoration competence of the secret transmitting delegation ticket to child nodes that it belongs in low rank level. By participants reuse own share and take part in different secret restoration, they who belong on hierarchical group can be possible different secret restoration by each participant's single share.

• Journal of KIISE:Computer Systems and Theory
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• v.30 no.9
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• pp.494-503
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• 2003

In this paper, we propose the implementation techniques of IC card chipset that is compatible with international standard ISO-7816 and supports WindowsCE operating system to expropriate various electronic cash and credit card. This IC card interface chip set is composed with 32 bit ARM720T Core and AES(Advanced Encryption System) cryptography module for electronic commerce. Six IC card interfaces support T=0, T=1 protocol and two of them are used to interface with user card directly, the others are used for interface with SAM card. In addition, It supports a LCD controller and USB interface for host. We improved the performance about 70% than software based It card chip set and verified using Hynix 0.35um process.

• The Transactions of the Korea Information Processing Society
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• v.7 no.10
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• pp.3128-3137
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• 2000

Secret sharing scheme is a cryptographic protocol in which a dealer distribures shares of a secret among a set of participants such that only authorized set of participants can recover the secret at a later. Secret sharing is an important cryptographic primitive in management of secret information, secure multiparty protocol and group-oriented cryptography, etc. In this paper, we propose an efficient, on-line secret sharing scheme based on one-way hash function. This scheme provides the property to share multiple secrets and allows participants to be added/deleted dynamically, without having to redistributo new shares. Proposed scheme has advantage to detect cheating and identify of all cheater, regardless of then number. Frthermore, it is more eficient than previous schemes.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.11 no.5
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• pp.97-104
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• 2001

In this paper, we propose Recoverable Password Based Key Exchange Protocol(RPKEP). RPKEP has user who has password, server which share the secret key information with user, and password recovery agency(PRA) which help to recover the user\`s password. Proposed protocol has some advantages that it is secure against off-line dictionary attack which is considered most important in password based key exchange protocol and suer\`s security is preserved even though user\`s secret information stored in the server is disclosed. By applying Chaum\`s blind signature scheme in the process of password recovery, even the PRA can\`t obtain any information about user\`s password.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.5 no.4
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• pp.667-674
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• 2015

Internet of things (IoT) has been a focus of research and widespread. Security and privacy are the key issues for IoT applications, and still faced with some enormous challenges. In order to facilitate this emerging domain, we analyzed the research progress of IoT, and pay attention to the security. By means of deeply analyzing the security architecture and features, the security requirements are required. And, we surveyed the demands and requirements.

• The Journal of the Korea Contents Association
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• v.5 no.3
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• pp.9-17
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• 2005

Recently, there are rapid development of information and communication technology and rapid growing of e-business users. We propose a method for security problem on the internet environment which changes from wire internet to wireless internet or wire/ wireless internet. Wireless e-business adopts credit card WPP protocol and AIP protocol proposed by ASPeCT. WAP, one of the protocol used by WPP has weakness of leaking out information from WG which connected wire and wireless communication. Certification chain based AIP protocol requires a lot of computation time and user IDs are known to others. We propose a Micro-Payment protocol based on credit card. Our protocol use the encryption techniques of the public key with ID to ensure the secret of transaction in the step of session key generation. IDs are generated using ECC based Weil pairing. We also use the certification with hidden electronic sign to transmit the payment result. The proposed protocol also solves the privacy protection and Non-repudiation problem.