• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.3
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• pp.35-43
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• 2003

The randomization of scalar multiplication in ECC is one of the fundamental concepts in defense methods against side-channel attacks. This paper proposes a countermeasure against simple and differential power analysis attacks through randomizing the transformed m-ary method based on a random m-ary receding algorithm. The proposed method requires an additional computational load compared to the standard m-ary method, yet the power consumption is independent of the secret key. Accordingly, since computational tracks using random window width can resist against SPA and DPA, the proposed countermeasure can improve the security for smart cards.

• 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.

• International Journal of Internet, Broadcasting and Communication
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• v.16 no.1
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• pp.17-28
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• 2024

As listed as one of the most important requirements for Post-Quantum Cryptography standardization process by National Institute of Standards and Technology, the resistance to various side-channel attacks is considered very critical in deploying cryptosystems in practice. In fact, cryptosystems can easily be broken by side-channel attacks, even though they are considered to be secure in the mathematical point of view. The timing attack(TA) and the simple power analysis attack(SPA) are such side-channel attack methods which can reveal sensitive information by analyzing the timing behavior or the power consumption pattern of cryptographic operations. Thus, appropriate measures against such attacks must carefully be considered in the early stage of cryptosystem's implementation process. The Montgomery multiplier is a commonly used and classical gadget in implementing big-number-based cryptosystems including RSA and ECC. And, as recently proposed as an alternative of building blocks for implementing post quantum cryptography such as lattice-based cryptography, the big-number multiplier including the Montgomery multiplier still plays a role in modern cryptography. However, in spite of its effectiveness and wide-adoption, the multiplier is known to be vulnerable to TA and SPA. And this paper proposes a new countermeasure for the Montgomery multiplier against TA and SPA. Briefly speaking, the new measure first represents a multiplication operand without 0 digits, so the resulting multiplication operation behaves in a very regular manner. Also, the new algorithm removes the extra final reduction (which is intrinsic to the modular multiplication) to make the resulting multiplier more timing-independent. Consequently, the resulting multiplier operates in constant time so that it totally removes any TA and SPA vulnerabilities. Since the proposed method can process multi bits at a time, implementers can also trade-off the performance with the resource usage to get desirable implementation characteristics.

• 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.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.25 no.2
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• pp.449-456
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• 2015

Recently, information security of IoT(Internet of Things) have been increasing to interest and many research groups have been studying for cryptographic algorithms, which are suitable for IoT environment. LEA(Lightweight Encryption Algorithm) developed by NSRI(National Security Research Institute) is commensurate with IoT. In this paper, we propose two first-order Correlation Power Analysis(CPA) attacks for LEA and experimentally demonstrate our attacks. Additionally, we suggest the mask countermeasure for LEA defeating our attacks. In order to estimate efficiency for the masked LEA, its operation cost is compared to operation time of masked AES.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.17 no.5
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• pp.65-72
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• 2007

In this paper, we investigate the several different types of higher-order differential side channel analysis (DSCA) attacks. We present that some of exiting higher-order DSCA attacks have some practical problem applying to two masked intermediate values being parallel processed. In order to solve this problem we propose a new higher-order DSCA attack using an efficient and simple preprocessing function. Using the proposed preprocessing function we clearly show that 2nd-order DSCA attacks are still a practical threat fur masked hardware implementations.

• ETRI Journal
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• v.31 no.5
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• pp.625-627
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• 2009

This letter describes an improved side-channel attack on DES with the first four rounds masked. Our improvement is based on truncated differentials and power traces which provide knowledge of Hamming weights for the intermediate data computed during the enciphering of plaintexts. Our results support the claim that masking several outer rounds rather than all rounds is not sufficient for the ciphers to be resistant to side-channel attacks.

• ETRI Journal
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• v.38 no.2
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• pp.387-396
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• 2016

This paper introduces a new type of collision attack on first-order masked Advanced Encryption Standards. This attack is a known-plaintext attack, while the existing collision attacks are chosen-plaintext attacks. In addition, our method requires significantly fewer power measurements than any second-order differential power analysis or existing collision attacks.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.390-393
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• 2014

The importance of this emerging information security and u-Korea or ubiquitous IT era, and the information security is more important. Especially, the small core device password encryption algorithm is an important part of the secure side channel attack cryptographic algorithms. However, it can provide high level of security, an adversary can attack small core device through implementation of cryptographic algorithms. In this paper describes for the Power Analysis attack and analyze the experimental environment.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.6
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• pp.125-134
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• 2004

When cryptosystem designers implement devices that computing power or memory is limited such as smart cards, PDAs and so on, not only he/she has to be careful side channel attacks(SCA) but also the cryptographic algorithms within the device has to be efficient using small memory. For this purpose, countermeasures such as Moiler's method, Okeya-Takagi's one and overlapping window method, based on window method to prevent SCA were proposed. However, Moiler's method and Okeya-Talngi's one require additional cost to prevent other SCA such as DPA, Second-Order DPA, Address-DPA, and so on since they are immune to only SPA. Also, overlapping window method has a drawback that requires big memory. In this paper, we analyze existing countermeasures and propose an efficient and secure countermeasure that is immune to all existing SCA using advantages of each countermeasure. Moreover, the proposed countermeasure can enhance the efficiency using mixed coordinate systems.