• Proceedings of the Korea Information Processing Society Conference
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• 2018.10a
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• pp.288-291
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• 2018

블록체인은 암호화폐의 기반이 되는 기술로 데이터를 P2P 분산 방식으로 체인 형태로 기록하여 보안성과 안전성을 갖?다. 중앙 집권화에서 벗어나 사용자들의 네트워크에서 자유롭고 안전한 거래를 가능하게 하는 블록체인은 현재 스마트 계약, 암호화폐, 개인 정보 인증 등 다양한 방법으로 활용되고 있다. 블록체인 사용자들은 거래의 안전성을 위해 채굴이라는 과정으로 블록을 인증하는데 절반 이상의 해시파워를 가진 공격자가 거래내역을 조작하는 것이 51% attack이다. 채굴자들은 채굴을 위해 전문 장비를 개발하고 이익을 도모하기 위해 모이면서 큰 집단으로 모이면서 51% attack에 대한 공격가능성이 높아졌고 실제로 엄청난 피해를 입힌 공격 사례가 있다. 따라서 본 논문은 51% attack의 사례와 기존 대응방안인 PoS 방식과 dPoW 방식 및 각 방식에 대한 한계를 분석하였고 이를 보완한 새로운 블록체인 모델을 제안한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.11a
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• pp.886-889
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• 2013

개인의 사생활 보호를 위한 익명성 확보는 네트워크상에서 다뤄지는 주요 논점 중 하나로서, 오래전부터 연구되어 수많은 기술이 제안되어 왔다. The Amnesic Incognito Live System(이하 Tails) 역시 이 중 하나로, PELD 설계 기반 하에 모든 인터넷 커넥션을 익명화하고 해당 디바이스 디스크에 흔적을 남기지 않는 강력한 Live OS이다. 이렇듯 Tails는 익명화에 있어 완성도 높은 시스템이라고 볼 수 있으나, 아직 해당 분야의 연구가 활발치 못해 공격 기법의 분석이 부족한 실정이다. 이를 바탕으로 본 문서는 Tails를 대상으로 한 소수의 기존 공격 기법들을 TOR 기반, Memory Analysis 기반, HTTP Keepalive 기반 등으로 세분화하여 나열하는 것을 주목적으로 두고 있다. 그리고 나아가 분석을 바탕으로 새로운 공격 가능성을 도출해내는 것이 최종 목적이다.

• Review of KIISC
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• v.31 no.3
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• pp.61-71
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• 2021

최근 블록체인 기술의 적용 범위가 전 산업으로 확대되고 있으며, 고부가가치 정보와 디지털 자산이 블록체인 분산 데이터베이스에 저장되고 관리되면서 블록체인을 대상으로 하는 보안 위협이 급격히 증가하고 있다. 특히 가용성 저하 공격, 분산 서비스 거부 공격, 비정상 거래, 악의적 거래, 51% 공격과 같이 블록체인을 대상으로 한 공격 기법이 고도화되고 피해 규모가 커지고 있다. 블록체인은 금융, 물류, 의료, 인증 등 전 산업 분야에 활용될 가능성이 높아지고 있어서 블록체인 네트워크 보안 위협을 신속하고 정확하게 탐지하는 기술에 대한 연구가 요구된다. 본 논문에서는 블록체인 네트워크 보안 위협에 대해 분석하고, 주요 위협 탐지 기술과 최신 동향을 분석한다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.25 no.5
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• pp.985-991
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• 2015

The user's secret key can be retrieved by various side channel leakage informations occurred during the execution of cryptographic RSA exponentiation algorithm which is embedded on a security device. The collision-based power analysis attack known as a serious side channel threat can be accomplished by finding some collision pairs on a RSA power consumption trace. Recently, an RSA exponentiation algorithm was proposed as a countermeasure which is based on the window method adopted combination of message blinding and exponent splitting. In this paper, we show that this countermeasure provides approximately $2^{53}$ attack complexity, much lower than $2^{98}$ insisted in the original article, when the window size is two.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.7
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• pp.68-75
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• 2013

Recently, there has been introduced various types of pairing computations to implement ID based cryptosystem for mobile ad hoc network. According to spreading the applications of pairing computations, various fault attacks have been proposed. Among them, a counter fault attack has been considered the strongest threat. Thus this paper proposes a new countermeasure to prevent the counter fault attack on Miller's algorithm. The proposed method is able to reduce the possibility of fault propagation by a random index of intermediate values. Additionally, it is difficult to challenge fault attacks on the proposed method since a simple side channel leakage of 'if' branch is eliminated.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.2
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• pp.70-79
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• 2013

Recently, there has been introduced various types of pairing computations to implement ID based cryptosystem for mobile ad hoc network. The Miller algorithm is the most popular algorithm for the typical pairing computation such as Weil, Tate and Ate. In this paper, we analyze the feasibility of concrete data fault injection attack, which was proposed by Whelan and Scott, in terms of regardless of round positions during the execution of the Miller algorithm. As the simulation results, the proposed attack that can be employed to regardless of round positions and coordinate systems is effective and powerful.

• The KIPS Transactions:PartC
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• v.17C no.1
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• pp.1-14
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• 2010

IEEE 802.15.4[1] has been standardized for the physical layer and MAC layer of LR-PANs(Low Rate-Wireless Personal Area Networks) as a technology for operations with low power on sensor networks. The standardization is applied to the variety of applications in the shortrange wireless communication with limited output and performance, for example wireless sensor or virtual wire, but it includes vulnerabilities for various attacks because of the lack of security researches. In this paper, we analyze the vulnerabilities against the denial of sleep attacks on the MAC layer of IEEE 802.15.4, and propose a detection mechanism against it. In results, we analyzed the possibilities of denial of sleep attacks by the modification of superframe, the modification of CW(Contention Window), the process of channel scan or PAN association, and so on. Moreover, we comprehended that some of these attacks can mount even though the standardized security services such as encryption or authentication are performed. In addition to, we model for denial of sleep attacks by Beacon/Association Request messages, and propose a detection mechanism against them. This detection mechanism utilizes the management table consisting of the interval and node ID of request messages, and signal strength. In simulation results, we can show the effect of attacks, the detection possibility and performance superiorities of proposed mechanism.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.1
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• pp.115-120
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• 2013

There are lots of vulnerability and chance to be attacked in wireless sensor networks, which has many applications. Among those attacks, sybil attack is to generate a lot of false node and to inject false information into networks. When a user uses such false information without recognizing the attack, there might be a disaster. Although authentication method can be used to protect such attack, the method is not a good choice in wireless sensor networks, where sensor nodes have a limited battery and low power. In this paper, we propose a novel method to detect sybil attack with a little extra overhead. The proposed method use the characteristics that there is a weak connection between a group of normal nodes and a group of false nodes. In addition, the method uses energy aware routing based on random routing and adds a little information into the routing. Experimental results show that the proposed method detects false node by more than 90% probability with a little energy overhead.

• The KIPS Transactions:PartC
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• v.11C no.7 s.96
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• pp.959-970
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• 2004

It has become more difficult to correspond an cyber attack quickly as patterns of attack become various and complex. However, current so curity mechanisms just have passive defense functionalities. In this paper, we propose new network suity architecture to respond various cyber attacks rapidly and to chase and isolate the attackers through cooperation between security zones. The proposed architecture makes it possible to deal effectively with cyber attacks such as IP spoofing or DDoS(Distributed Denial of Service), by using active packet technology including a mobile code on active network. Also, it is designed to have more active correspondent than that of existing mechanisms. We im-plemented these mechanisms in Linux routers and experimented on a testbed to verify realization possibility of attacker response framework using mobile code. The experimentation results are analyzed.

• Journal of Internet Computing and Services
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• v.9 no.2
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• pp.69-81
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• 2008

It has become more difficult to correspond a cyber attack quickly as patterns of attack become various and complex. However, current security mechanism just have passive defense functionalities. In this paper, we propose new network security mechanism to respond various cyber attacks rapidly and to chase and isolate the attackers through cooperation between security zones. The proposed mechanism makes it possible to deal effectively with cyber attacks such as IP spoofing, by using active packet technology including a mobile code on active network. Also, it is designed to hove more active correspondent than that of existing mechanisms. We implemented these mechanisms in Linux routers and experimented on a testbed to verify realization possibility of attacker response framework using mobile code. The experimentation results are analyzed.