• Proceedings of the Korea Information Processing Society Conference
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• 2016.10a
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• pp.241-242
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• 2016

안드로이드 시스템은 공개적인 구조 때문에 다양한 공격에 노출될 수 있다. 특히 공개된 앱의 코드를 재사용하는 앱 재사용(reuse) 공격에 취약하다. 안드로이드 앱 재사용 공격에서 공격자는 역공학을 통해서 파악한 기존 앱의 유용한 코드 블록을 재사용해서 악성앱을 만든다. 이러한 안드로이드 앱 재사용 공격에 대항하기 위해서 다양한 방어기법들이 제안되었다. 기존에 제안된 기법들이 앱 전체 코드에 대한 재사용 공격을 탐지하는데 반해, 본 논문에서는 앱에서 코드 블록 재사용에 대한 분석기법을 제안하고자 한다. 기본 아이디어는 Birthday paradox을 이용해서 앱에서 재사용되는 코드 블록에 대한 수리적 분석을 수행하는 것이다. 분석을 통해서 동일 코드 블록 재사용 확률은 전체 코드 블록중에서 재사용 코드 블록이 차지하는 비율과 코드 블록 재사용에 참여하는 악성앱들의 개수에 영향을 받는다는 것을 파악하였다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.19 no.1
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• pp.53-62
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• 2009

H. Gilbert et al. proposed a collision attack on 7-round reduced Rijndael[5]. Applying this attack, we propose collision attacks on 8-round reduced Crypton, 8-round reduced mCrypton in this paper. Attacks on Crypton requires $2^{161.6}$ time complexity with $2^{96}$ chosen plaintexts, respectively. The attack on mCrypton requires $2^{81.6}$ time complexity with $2^{48}$ chosen plaintexts. These results are the best attacks on Crypton and mCrypton in published literatures.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.2
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• pp.422-429
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• 2007

Location awareness is one of the key functionalities to build an U-city. Recently, many of works of the location-aware systems are emerging to commercially apply to on-going large-scale apartment complex based on U-city. As dwellers or cars being attached with active tags are moving in the U-city complex, the active tags periodically broadcast their own identifiers and receivers fixed along the street or in building use those information to calculate location of them. There are several issues to be considered for such an environment. The first is that the number of active tags operating in the same region are large as much as tens of thousands, and the second is that the active tags should be alive without change of batteries more than a year, hence low power consumption is very important. In this paper we propose i) a new architecture for location-aware system considering such issues, ii) technical issues to implement it using active tags, and iii) a mathematical analytic model to investigate overall performance and verify it by comparing with actual experimental results. Through the analysis we can show the theoretical boundary of the lowest packet loss rate and the maximum number of tags with acceptable performance for the systems based on active tags. The results can be applied to practical design of location-based systems of U-City projects.