• Journal of Advanced Navigation Technology
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• v.11 no.3
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• pp.329-336
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• 2007

The use of digital imaging technique and digital contents based on internet has grown rapidly for last several years, and the needs of digital image protection become more important. For the purpose of copyright protection on digital image, the verification of authentication techniques like content authentication, ownership authentication, illegal copy and etc are needed. Digital watermarking, the invisible encryption technique to insert digital watermark into image, the sophisticated perceptual information should be used for providing transparency and robustness of images on watermarking process. In this paper, we implement the digital watermarking algorithm for preventing forged attack, ownership protection and authentication by transforming the wavelet algorithms in frequency domain in terms of human visual system.

• Journal of Advanced Navigation Technology
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• v.13 no.5
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• pp.691-698
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• 2009

Chen et al. proposed a RFID authentication protocol for anti-counterfeiting and privacy protection. A feasible security mechanism for anti-counterfeiting and privacy protection was proposed using XOR and random number shifting operations to enhance RFID tag's security providing a low cost. However, their authentication protocol has some drawbacks and security problems because they did not consider the surrounding environments. We conduct analysis on the protocol and identify problematic areas for improvement of the research. We also provide enhanced authentication and update scheme based on the comment for efficient supply chain management. The proposed protocol was analyzed and compared with typical XOR based RFID authentication protocols and it was confirmed that our protocol has high safety and low communication cost.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.7B
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• pp.403-410
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• 2007

Neighbor Discovery (ND) protocol was proposed to discover neighboring hosts and routers in IPv6 wire/wireless local networks. ND protocol, however, has a problem that it is vulnerable to network attacks because ND protocol allows malicious users to impersonate other legitimate hosts or routers by forging ND protocol messages. To address the security problem, Secure Neighbor Discovery (SEND) protocol was proposed. SEND protocol provides address ownership proof mechanism, ND protocol message protection mechanism, reply attack prevention mechanism, and router authentication mechanism to protect ND protocol. In this paper, we design and implement SEND protocol in IPv6 local networks. And also, we evaluate and analyze the security vulnerability and performance of SEND protocol by experimenting the implemented SEND protocol on IPv6 networks.

• Journal of the Korea Computer Industry Society
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• v.3 no.8
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• pp.1105-1116
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• 2002

This paper has presented three types of key recovery methods, which are known as key escrow, key encapsulation, and trusted third party scheme. we have analyzed the existing key recovery products, which have been developed by the advanced nations for electronic commerce and electronic government. we have also analyzed the key recovery policies proposed by the advanced nations, such as The United States of America, Great Britain, and Japan. In this paper, several key recovery policies are proposed for the e-commerce and e-government system. And we have proposed key recovery scheme for the e-commerce system utilizing the on-line secret sharing scheme based on the Internet and public bulletin board.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.6
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• pp.937-942
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• 2002

The use of digital imaging technique and digital contents based on internet has grown rapidly for last several years, and the needs of digital image protection become more important. For the purpose of copyright protection on digital image, the verification of authentication techniques like content authentication, ownership authentication, illegal copy and etc are needed. Digital watermarking, the invisible encryption technique to insert digital watermark into image the sophisticated perceptual information should be used for providing transparency and robustness of images on watermarking process. In this paper, we implement the algorithm for preventing forged attack, ownership protection and authentication by transforming the wavelet algorithms in frequency domain in terms of human visual system.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.6
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• pp.288-295
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• 2005

Multi-signcryption scheme is an extension of signcryption scheme for multi-signers performing together the signcryption operation on messages, and it provides useful cryptographic functions such as confidentiality and authenticity for the sound circulation of messages through the Internet. In this paper, we show the weaknesses of the previous multi-signcryption schemes. And then we propose a new multi-signcryption scheme that improves the weaknesses and the efficiency of the previous schemes. Our scheme efficiently provides message flexibility, order flexibility, message verifiability, order verifiability, message confidentiality, message unforgeability, non-repudiation and robustness. Therefore, it is suitable for protecting messages and multi-signers from malicious attacks in the Internet.

• Proceedings of the Korea Information Processing Society Conference
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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 Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.7C
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• pp.743-750
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• 2003

With the expansion of computer technology the mobility of a mobile agent code having the flexibility in the dispersive computer situation is used to set up the applications distributed on the Internet. As it also has the ability to transmit the mobile code of a mobile agent and to receive it from a far-off host, the executive circumstances of the host system in which an agent is executed have to access to an agent code and the executive state capable of executing an agent code. Therefore, it is difficult to prevent the forgery, the alteration and the wrong execution of an agent from a malicious host. This dissertation suggests the mechanism which can protect an agent from the malicious action through the executive pursuit of a code-named mobile agent. The security of this mechanism is verified through the protective process of a mobile agent in this mechanism.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.04a
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• pp.615-619
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• 2000

최근 급증하고 있는 인터넷 전자상거래의 가장 필수적인 부분이 전자지불 시스템이다. 전자적으로 처리되는 지불시스템은 사용자의 익명성 보장, 지불정보의 위조 및 재사용방지 등의 특징을 가지며, 거래 주체들간의 신뢰구축을 위한 상호 인증이 요구된다. 디지털 기술의 발달로 소액의 디지털 상품들이 많이 등장함에 따라 소액 상품만을 결제하기 위한 소액지불 시스템의 필요성이 증대되면서, Millicent, PayWord, MicroMint, MPTP 등의 소액 지불 시스템들이 연구되었으나 아직 효과적으로 사용되지 못하고 있다. 이러한 소액 지불 시스템의 경우에는 소비자가 한 상점에서 연속적인 거래를 수행하는데 따르는 비용을 먼저 생각해야 한다. 그 이유는 소액거래를 하는 대부분의 소비자들은 여러 개의 상품을 연속적으로 구입하는 경향을 가지기 때문이다. 또한 거래 주체간의 대금결제의 편의성을 도모하기위한 선불방식에 대한 연구가 필요하다. 그러나, 기존의 소액 지불 시스템들은 연속거래에 있어 제한적이거나 소비자의 신용을 기반으로 한 후불방식을 채택하고 있어 소비자의 화폐남용에 대한 자원낭비의 문제를 안고있다. 이에 본 논문에서는 Hash Chain을 이용하여 연속거래에 적합한 선불방식의 소액전자지불 시스템을 제안한다.

• Korean Journal of Optics and Photonics
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• v.14 no.6
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• pp.630-635
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• 2003

We propose an encryption method using visual cryptography and virtual phase images. In the encryption process, the original image is shared by virtual images and the decryption key image. We multiply the virtual phase images with each complex image, which has the constant value of its sum after performing the phase modulation of the virtual images and the decryption key. The encryption cards are made by Fourier transforming the multiplied images. It is possible to protect information about the original image because the cards do not have any information from the original image. To reconstruct the original image, all the encryption cards are placed on each path of a Mach-Zehnder interferometer and then the lights passing through them are summed. Since the summed image is inverse Fourier transformed by a Fourier lens, the phase image is multiplied with the decryption key and the output image is obtained in the form of intensity on the CCD plane. Computer simulations show a good performance of the pro-posed optical security system.