• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.1
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• pp.221-227
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• 2014

When implementing cryptographic algorithms in mobile devices like smart cards, the security against side-channel attacks should be considered. Side-channel attacks try to find critical information from the side-channel infromation obtained from the underlying cryptographic devices' execution. Especially, the power analysis attack uses the power consumption profile of the devices as the side-channel information. This paper proposes a new gate-level countermeasure against the power analysis attack and the glitch attack and suggests how to apply the measure to securely implement AES.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.30 no.1
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• pp.39-49
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• 2020

In this paper, we show that the Chinese standard block cipher SM4 is vulnerable to the side channel attacks and present a countermeasure to resist them. We firstly validate that the secret key of SM4 can be recovered by differential power analysis(DPA) and correlation power analysis(CPA) attacks. Therefore we analyze the vulnerable element caused by power attack and propose a first order masking-based countermeasure to defeat DPA and CPA attacks. Although the proposed countermeasure unfortunately is still vulnerable to the profiling power attacks such as deep learning-based multi layer perceptron(MLP), it can sufficiently overcome the non-profiling attacks such as DPA and CPA.

• The KIPS Transactions:PartC
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• v.18C no.1
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• pp.7-14
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• 2011

Power analysis attack on low-power consumed security devices such as smart cards is very powerful, but it is required that the correlation between the measured power signal and the mid-term estimated signal should be consistent in a time instant while running encryption algorithm. The power signals measured from the security device applying the random clock do not match the timing point of analysis, therefore random clock is used as counter measures against power analysis attacks. This paper propose a new constant pitch based time alignment for power analysis with random clock power trace. The proposed method neutralize the effects of random clock used to counter measure by aligning the irregular power signals with the time location and size using the constant pitch. Finally, we apply the proposed one to AES algorithm within randomly clocked environments to evaluate our method.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2007.02a
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• pp.112-115
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• 2007

최근 부채널 공격으로 스마트 카드 같은 장치의 비밀키를 알아낼 수 있음이 알려지면서 많은 알고리즘에 대한 부채널 공격과 대웅 방안이 연구되고 있다. 차분전력분석은 부채널 공격의 일종으로 암호화 연산 중 발생하는 전력 소모 곡선을 통계적으로 분석하여 키를 알아내는 공격이다. 본 논문에서는 Hocker 형태의 IC칩 차분전력분석공격에 대한 실험 분석 모델을 설정한 후 이를 검증하고자 축소형 모델로 실험한다 실험 분석을 위하여 선정된 장치에 DES 암호알고리즘을 어셈블리로 구현한 후 8비트 마이크로프로세서 형 칩에 탑재하여 암호 알고리즘 실행 시에 발생되는 차분 전력 신호를 분석한다. 그리고 차분전력분석 공격에서 중요한 기술인 분류함수 설정에 따른 분석 성공 여부에 따른 비교를 한다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.16 no.4
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• pp.59-68
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• 2006

Although the cryptographic algorithms in IC chip such as smart card are secure against mathematical analysis attack, they are susceptible to side channel attacks in real implementation. In this paper, we analyze the security of smart card using a developed experimental tool which can perform power analysis attacks and fault insertion attacks. As a result, raw smart card implemented SEED and ARIA without any countermeasure is vulnerable against differential power analysis(DPA) attack. However, in fault attack about voltage and clock on RSA with CRT, the card is secure due to its physical countermeasures.

• Proceedings of the Korean Society of Computer Information Conference
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• 2011.06a
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• pp.71-74
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• 2011

2030년까지 한국에 Smart Grid를 구축할 계획을 가지고 추진하고 있다. Smart Grid는 지능형 전력망으로 기존의 전력망에 IT를 접목시켜 통신을 실시하여 양방향성을 가지게 된다. 기존의 전력망에 부가될 IT전기기기들은 기존에 IT가 지니고 있는 취약점들이 있어 기존의 Smart Grid공격에 노출되어 있다. 본 논문에서는 한국보다 먼저 구축되어서 활용되고 있는 미국의 Smart Grid에 대한 공격사례를 분석한다. 그리고 한국 Smart Grid에 대한 전기IT기기의 취약점을 분석하여, 한국 Smart Grid에 대한 예상 공격을 분석하고, 보안 대책을 제시한다. 본 논문은 한국 Smart Grid에 안정성과 보안성을 갖춘 기술 자료로 활용할 것이다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.19 no.2
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• pp.11-21
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• 2009

The NTRU cryptosystem proposed by Hoffstein et al. in 1990s is a public key cryptosystem based on hard lattice problems. NTRU has many advantages compared to other public key cryptosystems such as RSA and elliptic curve cryptosystems. For example, it guarantees high speed encryption and decryption with the same level of security, and there is no known quantum computing algorithm for speeding up attacks against NTRD. In this paper, we analyze the security of NTRU against the simple power analysis (SPA) attack and the statistical power analysis (STPA) attack such as the correlation power analysis (CPA) attack First, we implement NTRU operations using NesC on a Telos mote, and we show how to apply CPA to recover a private key from collected power traces. We also suggest countermeasures against these attacks. In order to prevent SPA, we propose to use a nonzero value to initialize the array which will store the result of a convolution operation. On the other hand, in order to prevent STPA, we propose two techniques to randomize power traces related to the same input. The first one is random ordering of the computation sequences in a convolution operation and the other is data randomization in convolution operation.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.32 no.6
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• pp.1059-1068
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• 2022

A Post-Quantum Cryptographic algorithm NTRU, which is designed by considering the computational power of quantum computers, satisfies the mathematically security level. However, it should consider the characteristics of side-channel attacks such as power analysis attacks in hardware implementation. In this paper, we verify that the private key can be recovered by analyzing the power signal generated during the decryption process of NTRU. To recover the private keys, the Simple Power Analysis (SPA), Correlation Power Analysis (CPA) and Differential Deep Learning Analysis (DDLA) were all applicable. There is a shuffling technique as a basic countermeasure to counter such a power side-channel attack. Neverthe less, we propose a more effective method. The proposed method can prevent CPA and DDLA attacks by preventing leakage of power information for multiplication operations by only performing addition after accumulating each coefficient, rather than performing accumulation after multiplication for each index.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.12
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• pp.2883-2890
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• 2013

Correlation power analysis attack takes place at the point of operating a known value and a hidden value from a master key as an input. The hidden value can be found by analyzing a correlation between the result value and the measured power signal during the operation, witch makes it possible to estimate the master key from the hidden value. However, the correlation power analysis attack can be very difficult by changing the conditions that make the power analysis possible, when the known value and the operation is hidden, when it is impossible to estimate the master key from the hidden value, or when the correlation between the result value and the power signal is considerably lowered. Therefore this study proposes a software countermeasure using a secrete intermediate key to witch these conditions are applied.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.4
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• pp.135-140
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• 2004

The ID-based cryptosystem and Power Analysis Attack are attracting many researchers and have been developed aggressively to date. Especially, DPA (Differential Power Analysis) attack has been considered to be the most powerful attack against low power devices, such as smart cards. However, these two leading topics are researched independently and have little hewn relations with each other. In this paper, we investigate the effect of power analysis attack against ID based cryptosystem. As a result, we insist that ID-based cryptosystem is secure against DPA and we only need to defend against SPA (Simple Power Analysis).