• Convergence Security Journal
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• v.5 no.3
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• pp.23-32
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• 2005

This paper presents a 128-bit Reversible Cellular Automata (RCA) based lightweight block cipher for Ubiquitous computing security. To satisfy resource-constraints for Ubiquitous computing, it is designed as block architecture based on Cellular Automata with high pseudo-randomness. Our implementation requires 704 clock cycles and consumes 2,874 gates for encryption of a 128-bit data block. In conclusion, the processing time outperformed that of AES and NTRU by 31%, and the number of gate was saved by 20%. We evaluate robustness of our implementation against both Differential Cryptanalysis and Strict Avalanche Criterion.

• KIPS Transactions on Computer and Communication Systems
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• v.4 no.2
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• pp.73-80
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• 2015

In the various application environments on the internet, we use verified cipher algorithm to protect personal information. Even so, if an application method isn't proper, the information you want to keep can be intercepted. One of the representative examples of it is a PADDING ORACLE ATTACK. This thesis studied about STRP, MIKEY, CMS, IPSec, TLS, IPTV, an application environment which apply CBC operational mode based on block cipher and CBC padding method, and about whether we can attack against the Padding Oracle Attack as well as the vulnerable points.

• Annual Conference of KIPS
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• 2024.05a
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• pp.367-370
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• 2024

양자컴퓨터 시대가 눈앞에 도래한 지금 차세대 암호로 주목받고 있는 양자 내성 암호는 다양한 수학적 알고리즘에 안전성을 기반하고 있으나 이 안전성을 위협하는 대표적인 공격 기법 중 하나인 부채널 분석 공격에 대응하기 위한 노력들이 계속되어 왔다. 이 논문에서는 코드 기반 양자 내성 암호를 중심으로 알고리즘에 위협적인 부채널 분석 공격에 대한 연구 동향을 분석하였다. 그리고 NIST 에서 PQC 표준화를 위해 Round 를 진행 중인 후보 중 하나인 코드 기반 알고리즘 MEDS 에 대해 소개하고, MEDS 알고리즘의 최적화를 위해 기존에 연구되었던 코드 기반 암호에 대한 부채널 분석 공격 대응 측면에서의 알고리즘의 안전성 확보라는 보안 비용과 하드웨어 가속 등을 통한 성능 향상이 적절한 조화를 이룰 수 있도록 설계하기 위한 방안에 대해 알아보았다.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 1999.12a
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• pp.113-119
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• 1999

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1992.06a
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• pp.490-494
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• 1992

• Journal of Internet Computing and Services
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• v.23 no.3
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• pp.21-33
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• 2022

This paper is to suggest the secure secret sharing system in order to outstandingly reduce the damage caused by the leakage of the corporate secret. This research system is suggested as efficient P2P distributed system kept from the centrally controlled server scheme. Even the bitcoin circulation system is also based on P2P distribution scheme recenly. This research has designed the secure circulation of the secret shares produced by Threshold Shamir Secret Sharing scheme instead of the shares specified in the torrent file using the simple, highly scalable and fast transferring torrent P2P distribution structure and its protocol. In addition, this research has studied to apply both Shamir Threshold Secret Sharing scheme and the securely strong multiple user authentication based on Collaborative Threshold Autentication scheme. The secure transmission of secret data is protected as using the efficient symmetric encryption with the session secret key which is safely exchanged by the public key encryption. Also it is safer against the leakage because the secret key is effectively alive only for short lifetime like a session. Especially the characteristics of this proposed system is effectively to apply the threshold secret sharing scheme into efficient torrent P2P distributed system without modifying its architecture of the torrent system. In addition, this system guaranttes the confidentiality in distributing the secret file using the efficient symmetric encryption scheme, which the session key is securely exchanged using the public key encryption scheme. In this system, the devices to be taken out can be dynamically registered as an user. This scalability allows to apply the confidentiality and the authentication even to dynamically registerred users.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.219-222
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• 2013

The Side Channel attack methods proposed by P.Kocher are mainly used for cryptanalysis different cipher algorithms even though they are claimed to be strongly secured. Those kinds of attacks depend on environment implementation especially on the hardware implementation of the algorithm to the crypto module. side-channel attacks are a type of attack introduced by P.Kocher and is applicable according to each environment or method that is designed. This kind of attack can analyze and also extract important information by reading the binary code data via measurement of changes in electricity(voltage) consumption, running time, error output and sounds. Thus, in this paper, we discuss recent SPA and DPA attacks as well as recent countermeasure techniques.

• Annual Conference of KIPS
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• 2005.05a
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• pp.827-830
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• 2005

본 논문은 DRM(Digital Rights Management)의 핵심요소기술인 디지털 비디오 워터마킹 기술에서 암호화 기법을 함께 적용하여 저작권 판별 및 콘텐츠 보호의 두 가지 역할을 수행하는 시스템을 제안하고자 한다. 본 논문에서는 저작권 정보를 공개키 기반의 RSA 암호화 방법으로 암호문을 만든 후 이진화 과정을 수행하여 워터마크 키 정보를 생성하였고, 워터마킹 기법으로는 통계적 모델의 계산 속도가 빠른 NVF(Noise Visibility Function) 방식의 Adaptive Stationary GG(Generalized Gaussian) model[1]의 기법을 사용하였다. 암호문은 사용자 컨트롤러에서 제어가 가능하도록 하여 권한이 부여된 사용자만이 재생이 가능하도록 하였다. 본 논문의 구성은 2장에서 암호화 과정을 설명하고, 3장에서는 기존의 기법과는 다른 통계적 접근의 워터마킹 기법을 적용한 과정을 설명하며, 4장에서는 제안한 방법이 실제 환경에서의 실험 결과를 보여준다. 마지막으로 5장에서는 결론과 개선점을 바탕으로 향후 연구방향을 제시한다. 본 논문에서 제안한 방법은 미래사회 인터넷에서의 올바른 디지털 콘텐츠 사용 문화 정책에 큰 역할을 할 것으로 기대된다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.4
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• pp.709-718
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• 2019

A lightweight block cipher CHAM designed for suitability in resource-constrained environment has reasonable security level and high computational performance. Since this cipher may contain intrinsic weakness on side channel attack, it should adopt a countermeasure such as masking method. In this paper, we implement the masked CHAM cipher on 32-bit microprosessor Cortex-M3 platform to resist against side channel attack and analyze their computational performance. Based on the shortcoming of having many round functions, we apply reduced masking method to the implementation of CHAM cipher. As a result, we show that the CHAM-128/128 algorithm applied reduced masking technique requires additional operations about four times.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.16 no.4
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• pp.139-146
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• 2006

A Signcryption proposed by Yuliang Zheng in 1997 is a hybrid public key primitive that combines a digital signature and a encryption. It provides more efficient method than a straightforward composition of an signature scheme with a encryption scheme. In a mobile communication environment, the authenticated key agreement protocol should be designed to have lower computational complexity and memory requirements. The password-based authenticated key exchange protocol is to authenticate a client and a server using an easily memorable password. This paper proposes an secure Authenticated Key Exchange protocol using Signcryption scheme. In Addition we also show that it is secure and a more efficient that other exiting authenticated key exchange protocol.