• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.9
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• pp.4727-4741
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• 2019

The lightweight block cipher Piccolo adopts Generalized Feistel Network structure with 64 bits of block size. Its key supports 80 bits or 128 bits, expressed by Piccolo-80 or Piccolo-128, respectively. In this paper, we exploit the security of reduced version of Piccolo from the first round with the pre-whitening layer, which shows the vulnerability of original Piccolo. As a matter of fact, we first study some linear relations among the round subkeys and the properties of linear layer. Based on them, we evaluate the security of Piccolo-80/128 against the meet-in-the-middle attack. Finally, we attack 13 rounds of Piccolo-80 by applying a 5-round distinguisher, which requires $2^{44}$ chosen plaintexts, $2^{67.39}$ encryptions and $2^{64.91}$ blocks, respectively. Moreover, we also attack 17 rounds of Piccolo-128 by using a 7-round distinguisher, which requires $2^{44}$ chosen plaintexts, $2^{126}$ encryptions and $2^{125.49}$ blocks, respectively. Compared with the previous cryptanalytic results, our results are the currently best ones if considering Piccolo from the first round with the pre-whitening layer.

• Proceedings of the Korea Information Processing Society Conference
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• 2017.04a
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• pp.340-342
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• 2017

국내 기업과 기관을 대상으로 하는 APT(Advanced Persistent Treat) 공격은 꾸준히 발생하고 있다. 이에 대응하기 위해 보안 담당자는 다양한 보안솔루션을 도입하고 있지만, 반대로 보안 솔루션에 의해 공격당하는 사례가 발생하고 있다. 보안 솔루션에 의한 침해사고는 백신과 같은 엔드 포인트(End Point) 보안 솔루션을 공격하는 사례가 많지만, 네트워크 보안솔루션의 취약점을 이용하여 직접적으로 공격할 수 있는 가능성이 충분히 있다. 본 논문은 네트워크 보안 솔루션을 분석하여 확인한 취약점을 바탕으로 공격 시나리오를 제시한다. 이를 통해 네트워크 보안 솔루션에 의한 공격을 사전에 고려하여 대비할 수 있도록 한다.

• Proceedings of the KAIS Fall Conference
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• 2010.11a
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• pp.189-193
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• 2010

SIP 프로토콜 기반 VoIP 서비스는 편리함과 저렴한 통신비용으로 사용자 수가 급증하고 있다. 하지만 Text 형태의 SIP 헤더 정보를 UDP 방식으로 전송하기 때문에 손쉽게 위변조 할 수 있으며, 최근 SIP를 통해 제공되는 다양한 형태의 부가서비스에 대한 보안 위협이 증가하고 있다. FMC 폰을 통해 제공되는 동시착신, 착신전환, 3인통화 등과 같은 부가서비스에 대한 공격을 통해 과금우회 공격 등을 수행할 수 있다. 따라서 본 연구에서는 FMC 환경에서 제공되는 주요 SIP 부가서비스를 대상으로 각각의 취약성에 대해 조사 분석하였으며, 분석된 내용을 중심으로 SIP 기반 인터넷전화 부가서비스에 대한 공격 시나리오를 단계별로 설계 및 개발하였다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2015.01a
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• pp.267-269
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• 2015

본 논문에서는 고성능 컴퓨팅 시스템의 성능 향상을 위한 효율적인 동적 작업부하 균등화 정책을 제안한다. 이 정책은 시스템 자원인 CPU와 메모리를 효율적으로 사용하여 고성능 컴퓨팅 시스템의 처리량을 최대화하고, 각 작업의 수행시간을 최소화한다. 또한 이 정책은 수행중인 작업의 메모리 요구량과 각 노드의 부하 상태를 파악하여 작업을 동적으로 할당한다. 이때 작업을 할당 받은 노드가 과부하 상태가 되면 다른 노드로 작업을 이주시켜 각 노드의 작업부하를 균등하게 유지함으로써 작업의 대기시간을 줄이고, 각 작업의 수행시간을 단축한다. 본 논문에서는 시뮬레이션을 통하여 제안하는 동적 작업부하 균등화 정책이 기존의 메모리 기반의 작업부하 균등화 정책에 비해 고성능 컴퓨팅 시스템의 성능 향상 면에서 우수함을 보인다.

• Journal of the Korea Society for Simulation
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• v.13 no.3
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• pp.21-29
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• 2004

The major objective of this paper is to analyze network vulnerabilities using the SIMVA (SIMualtion-based Vulnerability Analyzer). SIMVA is capable of monitor network status and analyze vulnerabilities automatically. To do this, we have employed the advanced modeling and simulation concepts such as SES/MB (System Entity Structure / Model Base) framework, DEVS (Discrete Event System Specification) formalism, and experimental frame for developing network security models and simulation-based analysis of vulnerability. SIMVA can analyze static vulnerability as well as dynamic vulnerability consistently and quantitatively. In this paper, we verified and tested the capability of application of SIMVA by slammer worm attack scenario.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.19 no.3
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• pp.271-287
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• 2015

In this article, a more generalized form of the impact time and angle control guidance law is proposed based on the linear quadratic optimal control methodology. For the purpose on controlling an additional constraint such as the impact time, we introduce an additional state variable that is defined to be the jerk (acceleration rate). Additionally, in order to provide an additional degree of freedom in choosing the guidance gains, the performance index that minimizes the control energy weighted by an arbitrary order of time-to-go is considered in this work. First, the generalized form of the impact angle control guidance law with an additional term which is used for the impact time control is derived. And then, we also determine the additional term in order to achieve the desired impact time. Through numbers of numerical simulations, we investigate the superiority of the proposed guidance law compared to previous guidance laws. In addition, a salvo attack scenario with multiple missile systems is also demonstrated.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.3
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• pp.491-501
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• 2019

In side-channel analysis, which exploit physical leakage from a cryptographic device, deep learning based attack has been significantly interested in recent years. However, most of the state-of-the-art methods have been focused on classifying side-channel information in a profiled scenario where attackers can obtain label of training data. In this paper, we propose a new method based on deep learning to improve non-profiling side-channel attack such as Differential Power Analysis and Correlation Power Analysis. The proposed method is a signal preprocessing technique that reduces the noise in a trace by modifying Auto-Encoder framework to the context of side-channel analysis. Previous work on Denoising Auto-Encoder was trained through randomly added noise by an attacker. In this paper, the proposed model trains Auto-Encoder through the noise from real data using the noise-reduced-label. Also, the proposed method permits to perform non-profiled attack by training only a single neural network. We validate the performance of the noise reduction of the proposed method on real traces collected from ChipWhisperer board. We demonstrate that the proposed method outperforms classic preprocessing methods such as Principal Component Analysis and Linear Discriminant Analysis.

• Journal of the Korea Society of Computer and Information
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• v.19 no.10
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• pp.99-106
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• 2014

In this paper, we analyze weaknesses of the biometrics-based user authentication scheme proposed by An. The result of analysis An's authentication scheme by the login success scenario proposed in this paper, if the attacker successes to get user's random number, he/she can pass user authentication phase of the legal server. Also the biometrics guessing scenario proposed in this paper shows the legal user's the biometric information is revealed in lost smart card. Since An's authentication scheme submit user ID and biometrics in plain text to the server, it is very vulnerable to inner attack and it is not provide the user anonymity to the server as well as the one to the third by user ID in plain text. Besides An's authentication scheme is contextual error too, due to this, it has weakness and so on that it did not check the validity of the smart card holder.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.4
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• pp.857-869
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• 2016

It is a well-known fact that password based authentication system has been threatened for crucial data leakage through monitoring key log. Recently, to prevent this type of attack using keystroke logging, virtual onscreen keyboards are widely used as one of the solutions. The virtual keyboards, however, also have some crucial vulnerabilities and the major weak point is that important information, such as password, can be exposed by tracking the trajectory of the mouse cursor. Thus, in this paper, we discuss the vulnerabilities of the onscreen keyboard, and present hypothetical attack scenario and a method to crack passwords. Finally to evaluate the performance of the proposed scheme, we demonstrate an example experiment which includes attacking and cracking by utilizing password dictionary and analyze the result.

• Journal of Information Technology Services
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• v.19 no.1
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• pp.145-158
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• 2020

With the development and widespread application of online shopping, the number of online consumers has increased. With one click of a mouse, people can buy anything they want without going out and have it sent right to the doors. As consumers benefit from online shopping, people are becoming more concerned about protecting their privacy. In the group buying scenario described in our paper, online shopping was regarded as intra-group communication. To protect the sensitive information of consumers, the polynomial-based encryption key sharing method (Piao et al., 2013; Piao and Kim, 2018) can be applied to online shopping communication. In this paper, we analyze security problems by using a polynomial-based scheme in the following ways : First, in Kamal's attack, they said it does not provide perfect forward and backward secrecy when the members leave or join the group because the secret key can be broken in polynomial time. Second, for simultaneous equations, the leaving node will compute the new secret key if it can be confirmed that the updated new polynomial is recomputed. Third, using Newton's method, attackers can successively find better approximations to the roots of a function. Fourth, the Berlekamp Algorithm can factor polynomials over finite fields and solve the root of the polynomial. Fifth, for a brute-force attack, if the key size is small, brute force can be used to find the root of the polynomial, we need to make a key with appropriately large size to prevent brute force attacks. According to these analyses, we finally recommend the use of a relatively reasonable hash-based mechanism that solves all of the possible security problems and is the most suitable mechanism for our application. The study of adequate and suitable protective methods of consumer security will have academic significance and provide the practical implications.