• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.4
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• pp.923-941
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• 2017

A side-channel attack is a method of attacking a cipher based on physical information of a cryptographic device. The masking method, which is a typical method overcoming this attack, is a method of calculating an arbitrary masking value at the round intermediate value through rounds. Thus, it is difficult to guess the intermediate value by the side-channel attack, but if the masking operation is applied to all rounds of the encryption algorithm, the encryption process may become overloaded. Therefore, it is practical to use a reduced-round masking technique that applies a masking technique to only a part of the cipher for lightweight equipment such as Internet of Things(IoT) and wearable devices. In this paper, we describe a Hamming weight filtering for SIMON family with reduced-round masking technique and it is shown that first round key recovery is possible through actual programming.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.4
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• pp.709-718
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• 2019

A lightweight block cipher CHAM designed for suitability in resource-constrained environment has reasonable security level and high computational performance. Since this cipher may contain intrinsic weakness on side channel attack, it should adopt a countermeasure such as masking method. In this paper, we implement the masked CHAM cipher on 32-bit microprosessor Cortex-M3 platform to resist against side channel attack and analyze their computational performance. Based on the shortcoming of having many round functions, we apply reduced masking method to the implementation of CHAM cipher. As a result, we show that the CHAM-128/128 algorithm applied reduced masking technique requires additional operations about four times.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.25 no.2
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• pp.253-260
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• 2015

The side-channel attack is widely known as an attack on implementations of cryptographic algorithms using additional side-channel information such as power traces, electromagnetic waves and sounds. As a countermeasure of side channel attack, the masking method is usually used, however full-round masking makes the efficiency of ciphers dramatically decreased. In order to avoid such a loss of efficiency, one can use reduced-round masking. In this paper, we describe a side channel attack on the lightweight block cipher LEA with the first one~six rounds masked. Our attack is based on differentials and power traces which provide knowledge of Hamming weight for the intermediate data computed during the enciphering of plaintexts. According to our experimental result, it is possible to recover 25 bits of the first round key in LEA-128.