• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.674-677
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• 2003

Modern society is information-oriented society that allow letters in electron, telecommunication, computer, highly Information-Communication and information processing by great development of semi-conductor technologies. All businesses are depending on computer. Also, Great many user according to development who is worth watching eagerly of computer network and utilization of database and technology could collect, search, handle, transmit and store data at the same time using computer. But, while processing and use of information that use computer become convenient, exposure of data became serious relatively. For these reason, Security problem of data that need the secret rose. Accordingly, new encryption methods to use computer for security of data are presented and are developed continuously. Studied about DES, 3DES, RSA, ECC algorithm to select cipher algorithm to use in research hereafter in this treatise.

• Journal of KIISE:Computing Practices and Letters
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• v.6 no.3
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• pp.348-355
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• 2000

Loyalty is a bonus point that a customer earns in reward of purchasing goods of a shop or a manufacturer. The management of loyalty such as issuing, accounting, reimbursing is carried out by the loyalty system. Traditional loyalty systems were proprietary. As a result, the systems are not interoperable with each other. However, our loyalty system allows a group of merchants join together and use the same IC card to operate their own loyalty programs. Data and counters can be shared or totally isolated, using secret codes and keys. The loyalty pool system communicates with the loyalty service providers over the Internet and performs the management of loyalty in fully automated manner. This paper describes the functional architecture and internal behavior of the loyalty pool system along with the communication protocols.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.3
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• pp.351-358
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• 2013

In 2008, Pointcheval and Zimmer have presented multi-factor authenticated key exchange protocol with client's secret key, password, biometrics. However, it has been found to be flawed by Hao and Clarke if an attacker has single authentication factor (password), then the attacker can deduce other authentication factors. Interestingly, its countermeasure has not been presented due to the difficulty of design and structural problem. In this paper, an efficient countermeasure is briefly presented and its security is discussed as well.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.5
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• pp.1104-1109
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• 2015

Due to the rapid growth in digital contents, it is important for us to design a high speed and secure encryption algorithm which is able to comply with the existing and future needs. This paper proposes an alternative approach for self-decimated LM-128 summation sequence generator, which will generate a higher throughput if compared to the conventional generator. We design and implement a threshold clock-controlled LM-128 and prove that it has a lower clock cycle and hence giving a higher key stream generation speed. The proposed threshold clock-control LM-128 generator consists of 256 bits inner state with 128 bits secret key and initialization vector. The cipher achieves a security level of 128 bits to be adapted to the digital contents security with high definition and high quality.

• Journal of Korea Multimedia Society
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• v.7 no.12
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• pp.1719-1728
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• 2004

The fusion of Internet technology and applications with wireless communication provides a new business model and promises to extend the possibilities of commerce to what is popularly called mobile commerce, or m-commerce. In mobile Internet banking service through wireless local area network, security is a most important factor to consider. We describe the development of security service for mobile Internet banking on Personal Digital Assistants (PDAs). Banking Server and Authentication Server were developed to simulate banking business and to support certificate management of authorized clients, respectively. To increase security, we took hybrid approach in implementation: symmetric block encryption and public-key encryption. Hash function and random number generation were exploited to generate a secret key. The data regarding banking service were encrypted with symmetric block encryption, RC4, and the random number sequence was done with public-key encryption. PDAs communicate through IEEE 802.IIb wireless LAN (Local Area Network) to access banking service. Several banking services and graphic user interfaces, which emulatedthe services of real bank, were developed to verity the working of each security service in PDA, the Banking Server, and the Authentication Server.

• Proceedings of the Korean Society of Computer Information Conference
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• 2013.07a
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• pp.173-175
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• 2013

본 논문에서는 정보통신망 이용촉진 및 정보보호 등의 관한 법률에서 '타인'의 범위에 관한 해석을 논점으로 삼고 있다. 대법원은 위 법 제49조의 '타인'의 범위에 관한 해석에서 생존한 사람뿐만 아니라 사망한 자도 포함하여 해석하고 있다. 물론 동법의 사자(死者)도 정보통신망의 안정성과 정보의 신뢰성 확보를 위해 포섭하여 해석할 수 있다는 견해가 존재할 수 있지만 형법 및 형사특별법은 죄형법정주의라는 이념상 허용될 수 없다는 견해가 타당하다. 형사법의 해석은 형벌이라는 가혹한 법률효과를 예정하고 있으므로 형벌법규의 해석은 엄격해야 하고 명문규정의 의미를 피고인에게 불리한 방향으로 확장해석하거나 유추해석을 해서는 안된다. 만약 동법 제49조의 '타인'의 범위에 사자(死者)를 포함한다면 법률해석의 방법인 문리해석, 논리해석, 목적론적 해석, 헌법 합치적 해석에도 반하므로 동법에서 '타인'의 범위에 사자(死者)를 포함시키고자 한다면 동법의 개정을 통해 법규 수범자에게 예측가능성을 확보할 수 있도록 용어의 분명한 정의규정이 입법을 통해 반영되어야 한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.2
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• pp.389-395
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• 2000

Digital Watermarking is a research area which aims at hiding secret information in digital multimedia content such as images, audio, and video. In this paper, we propose a new watermarking method with visually recognizable symbols into the digital images using wavelet transform, spread spectrum method and multilevel threshold value in considering the wavelet coefficients. The information of watermark can be extracted by subtracting wavelet coefficients with the original image and the watermarked image. The results of this experiment show that the proposed algorithm was superior to other similar watermarking algorithms. We showed Watermarking algorithm in JPEG lossy compression, resizing, LSB(Least Significant Bit) masking, and filtering.

• The Journal of Korean Association of Computer Education
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• v.7 no.1
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• pp.45-53
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• 2004

Ad-Hoc network is wireless network architecture without infrastructure. We encounter new types of security problems in Ad-Hoc networks because such networks have little or no support from infrastructure. Thus, wireless communications need security mechanisms in order to guarantee the integrity and the privacy of the communication, as well as the authentication of the entities involved. Many practical systems have been proposed. The most familiar system is the Diffie-Hellman key distribution system. This algorithm allows the establishment of a cryptographic secret key between two entities. If more than two users want to compute a common key, then a group key agreement system is used. This paper discusses several group key agreement systems and presents two efficient fault tolerant methods to perform successful group key agreement.

• Journal of Information Technology Services
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• v.3 no.2
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• pp.119-127
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• 2004

A mobile ad hoc network(MANET) is a network where a set of mobile devices communicate among themselves using wireless transmission without the support of a fixed network infrastructure. The use of wireless links makes MANET susceptible to attack. Eavesdroppers can access secret information, violating network confidentiality, and compromised nodes can launch attack from within a network. Therefore, the security for MANET depends on using the cryptographic key, which can make the network reliable. In addition, because MANET has a lot of mobile devices, the authentication scheme utilizing only the symmetric key cryptography can not support a wide range of device authentication. Thereby, PKI based device authentication technique in the Ad Hoc network is essential and the paper will utilize the concept of PKI. Especially, this paper is focused on the key management technique of PKI technologies that can offer the advantage of the key distribution, authentication, and non-reputation, and the issuing and managing technique of certificates based on clustering using Threshold Cryptography for secure communication in MANET.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.2
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• pp.751-765
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• 2012

Key establishment protocols are fundamental for establishing secure communication channels over public insecure networks. Security must be given the topmost priority in the design of a key establishment protocol. In this work, we provide a security analysis on two recent key establishment protocols: Harn and Lin's group key transfer protocol and Dutta and Barua's group key agreement protocol. Our analysis shows that both the Harn-Lin protocol and the Dutta-Barua protocol have a flaw in their design and can be easily attacked. The attack we mount on the Harn-Lin protocol is a replay attack whereby a malicious user can obtain the long-term secrets of any other users. The Dutta-Barua protocol is vulnerable to an unknown key-share attack. For each of the two protocols, we present how to eliminate their security vulnerabilities. We also improve Dutta and Barua's proof of security to make it valid against unknown key share attacks.