• Journal of the Korea Institute of Information Security & Cryptology
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• v.20 no.4
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• pp.109-115
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• 2010

Differential Power Analysis (DPA) is well known as one of efficient physical side-channel attack methods using leakage power consumption traces. However, since the power traces usually include the components irrelevant to the encryption, the efficiency of the DPA attack may be degraded. To enhance the performance of DPA, we introduce a pre-processing technique which extracts the encryption-related parts from the measured power consumption signals. Experimental results show that the DPA attack with the use of the proposed pre-processing method detects correct cipher keys with much smaller number of signals compared to that of the conventional DPA attack.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2002.11a
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• pp.575-579
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• 2002

스마트카드는 내부의 암호 알고리듬이 수행될 때, 비밀키와 관련된 여러 가지 물리적인 정보가 누출될 가능성이 있다. 이러한 물리적 정보 중에서 소비되는 전력을 측정하고 분석하는 차분 전력분석 공격은 매우 강력한 방법이다. 본 논문에서는 시차공격과 단순전력분석 공격에 대응하는 몽고메리 멱승 알고리듬과 스칼라 상수배 알고리듬이 구현된 스마트카드에서 차분 전력 분석 공격의 방법 중에서 동일한 메시지를 이용하는 MESD 공격을 실험하고 실험과정에서 소모전력의 측정 개수와 표본화율 그리고 잡음의 관계를 분석한다.

• 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.

• Proceedings of the Korean Information Science Society Conference
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• 2010.06d
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• pp.11-15
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• 2010

본 논문에서는 유비쿼터스 환경에서 그 환경을 구성하는 주요 디바이스들에 대하여 물리적인 공격을 통해 내부에 존재하는 비밀키 값과 같은 중요한 정보를 쉽게 찾아낼 수 있는 보다. 효율적인 2차 차분전력분석 기법을 제안한다. 이 기법은 마스킹이 적용된 디바이스에서도 쉽게 그 키 값을 찾아내는 기법으로 기존의 전처리함수를 이용한 2차 차분전력분석 공격 기법과 제안하는 전처리함수를 적용한 기법을 실제로 각각 구현하여 성능을 분석하고 비교함으로써 제안하는 전처리함수를 이용하여 2차 DPA 공격을 했을 때 기존의 공격보다 더 강화되고 위협적인 물리적 공격임을 실험적으로 검증한다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.5
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• pp.93-101
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• 2008

Side channel attacks are well known as one of the most powerful physical attacks against low-power cryptographic devices and do not take into account of the target's theoretical security. As an important succeeding factor in side channel attacks (specifically in DPAs), exact time-axis alignment methods are used to overcome misalignments caused by trigger jittering, noise and even some countermeasures intentionally applied to defend against side channel attacks such as random clock generation. However, the currently existing alignment methods consider only on the position of signals on time-axis, which is ineffective for certain countermeasures based on time-axis misalignments. This paper proposes a new signal alignment method based on interpolation and decimation techniques. Our proposal can align the size as well as the signals' position on time-axis. The validity of our proposed method is then evaluated experimentally with a smart card chip, and the results demonstrated that the proposed method is more efficient than the existing alignment methods.

• Journal of Internet Computing and Services
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• v.4 no.3
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• pp.1-8
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• 2003

The power analysis attack is a physical attack which can be applied to the cryptosystems such as smartcard. We try to experimental attack to a smart card which implemented Elliptic Curve Cryptosystem adopting NAF algorithm as a secret key recording method. Our differential power analysis attack is a potential threat to that implementation. The attacker measures the power traces during the multiplication with secret key bits in a target smart card and the multiplication with the guessed bits in other experimental one. The comparison of these two traces gives a secret bit, which means that attacker can find all secret key bits successively.

• 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 Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.9B
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• pp.1369-1380
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• 2010

In this paper, we propose the efficient Second-Order Differential Power Analysis attack, which has ability to find significant information such as secret key in the devices consisting IT convergence environment such as Smartgrid, Advanced Metering Infrastructure(AMI) and ZigBee-based home networking service. This method helps to find the secret key easily at a device, even though it uses a countermeasure like masking which makes First-Order DPA attack harder. First, we present the performance results of our implementation which implements practical Second-Order DPA attack using the existing preprocessing function, and analyze it. Then we propose a stronger preprocessing function which overcomes countermeasures like masking. Finally, we analyze the results of the Second-Order CPA attack using proposed preprocessing function and verify that proposed scheme is very threatening to the security fields of IT convergence technology through the experimental results.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.6A
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• pp.17-25
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• 2008

The differential power attack (DPA)[8] is a very powerful side-channel attack tool against various cryptosystems and the masking method[10] is known to be one of its algorithmic countermeasures. But it is non-trivial to apply the masking method to non-linear functions, especially, to arithmetic adders. This paper proposes simple and efficient masking methods applicable to arithmetic adders. For this purpose, we use the fact that every combinational logic circuit (including the adders) can be decomposed into basic logic gates (AND, OR, NAND, NOR, XOR, XNOR, NOT) and try to devise efficient masking circuits for these basic gates. The resulting circuits are then applied to the arithmetic adders to get their masking algorithm. As applications, we applied the proposed masking methods to SEED and SHA-1 in hardware.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.5
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• pp.1099-1103
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• 2016

The user's secret key can be retrieved by the leakage informations of power consumption occurred during the execution of scalar multiplication for elliptic curve cryptographic algorithm which can be embedded on a security device. Recently, a carry random recoding method is proposed to prevent simple power and differential power analysis attack by recoding the secret key. In this paper, we show that this recoding method is still vulnerable to the differential power analysis attack due to the limitation of the size of carry bits, which is a different from the original claim.