• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.1
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• pp.5-15
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• 2016

Power analysis attacks are techniques to analyze power signals to find out the secrets when cryptographic algorithm is performed. One of the most famous countermeasure against power analysis attacks is masking methods. Masking types are largely classified into two types which are boolean masking and arithmetic masking. For the cryptographic algorithm to be used with boolean and arithmetic masking at the same time, the converting algorithm can switch between boolean and arithmetic masking. In this paper we propose an algorithm for switching from boolean to arithmetic masking using storage size at less cost than ones. The proposed algorithm is configured to convert using the look-up table without the least significant bit(LSB), because of equal the bit of boolean and arithmetic masking. This makes it possible to design a converting algorithm compared to the previous algorithm at a lower cost without sacrificing performance. In addition, by applying the technique at the LEA it showed up to 26 percent performance improvement over existing techniques.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.3
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• pp.69-77
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• 2008

In the recent years, power attacks were widely investigated, and so various countermeasures have been proposed. In the case of block ciphers, masking methods that blind the intermediate results in the algorithm computations(encryption, decryption, and key-schedule) are well-known. Applications of masking methods are able to vary in different block ciphers, therefore suitable masking methods about each ciphers have been researched. Existed methods of ARIA have many revisions of mask value. And because existed masking methods pay no regard for key schedule, secret information can be exposed. In the case of ARIA, this problem is more serious than different block ciphers. Therefore we proposes an efficient masking scheme of ARIA including the key-schedule. Our method reduces time-complexity of ARIA encryption, and solve table-size problem of the general ARIA masking scheme from 256*8 byte to 256*6 byte.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2002.11a
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• pp.183-186
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• 2002

본 논문에서는 신호의 마스킹 특성을 이용한 Inter-Band Smoothing 기법을 통한 음질 개선 연구를 하였다. 이것은 임계 대역 신호 처리 후 신호의 전체 신호 대 마스킹 비를 보상해 주는 방식으로, 각 대역의 여기(Excitation) 에너지로부터 근사화 시킨 전역 마스킹 임계치를 통한 보상 기법이다. 잡음 에너지 제어를 통한 음질 개선알고리즘을 이용한 실험 결과 보다 자연스러운 음질의 제공을 통해 MOS의 개선을 확인 할 수 있었다.

• The KIPS Transactions:PartC
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• v.17C no.3
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• pp.233-242
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• 2010

In the recent years, power attacks were widely investigated, and so various countermeasures have been proposed. In the case of block ciphers, masking methods that blind the intermediate results in the algorithm computations(encryption, decryption) are well-known. In case of SEED block cipher, it uses 32 bit arithmetic addition and S-box operations as non-linear operations. Therefore the masking type conversion operations, which require some operating time and memory, are required to satisfy the masking method of all non-linear operations. In this paper, we propose a new masked S-boxes that can minimize the number of the masking type conversion operation. Moreover we construct just one masked S-box table and propose a new formula that can compute the other masked S-box's output by using this S-box table. Therefore the memory requirements for masked S-boxes are reduced to half of the existing masking method's one.

• 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.26 no.6
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• pp.1431-1441
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• 2016

In case of ARX based block cipher algorithms with masking countermeasures, there is a need for a method to convert between Boolean masking and arithmetic masking. However, to apply masking countermeasures to ARX based algorithms is less efficient compared to masked AES with single masking method because converting between Boolean and arithmetic masking has high computation time. This paper shows performance results on 32-bit platform implementations of LEA with various masking conversion countermeasures against first order side channel attacks. In the implementation point of view, this paper presents computation time comparison between actual measurement value and theoretical one. This paper also confirms that the masked implementations of LEA are secure against first order side channel attacks by using a T-test.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2002.12a
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• pp.353-356
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• 2002

본 논문은 카오스 신호를 이용하여 안전한 음성신호의 전송을 위한 아날로그 비화통신 시스템의 성능분석에 관한 연구이다. 기존의 카오스 동기화 및 카오스 변조통신 알고리즘을 개선하여 실제 통신환경에서 발생하는 다양한 조건들을 적용하여 음성신호의 복원능력을 모의실험으로 분석하였다. 일반적인 PC 제어기법과 제안한 피드백 마스킹 기법을 사용하여 송신단에서 음성신호를 카오스 신호로 마스킹하여 변조하고, 통신채널에 잡음신호를 추가하여 전송하였다. 수신단에서는 카오스 응답시스템을 이용하여 음성신호를 복조하고, 복원성능을 계산하기 위하여 아날로그 복원 에러신호의 평균전력을 제안하여 계산하였다. 실험결과 마스킹 정도, 파라미터들의 민감성, 채널잡음 등에 대하여 PC 제어기법보다 피드백 제어기법의 복원성능이 우수함을 확인할 수 있었다. 또한 로렌쯔 카오스 시스템을 비화통신시스템에 사용할 경우 파라미터들의 조합으로 암호키를 구성해야 하므로 키값들의 선정에 기준이 되는 파라미터 변화율에 대응하는 복원에러율의 관계를 실험 값으로 구하였다.

• Review of KIISC
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• v.33 no.3
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• pp.85-96
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• 2023

LWE-like 암호는 지난 몇 년간 표준화 선정 대상 유력 후보로 주목받았다. 실제로 NIST가 선정한 양자내성암호 표준화 진행 대상 4종 중 2종이 LWE 기반 암호인만큼, LWE-like 암호는 많은 중요성을 가지고 있으며 이에 따라 LWE-like 암호에 대한 부채널 분석/대응 기술 연구가 활발히 진행되었다. 특히 전력/전자파를 이용한 분석과 이에 대한 마스킹 대응기법 연구가 많은 결실을 맺었다. 따라서 본 논문은 LWE-like KEM/전자서명에 대한 부채널 대응기술 중 마스킹 기법 동향을 서술한다. LWE-like KEM에 대한 1차 및 고차 마스킹 기법 연구 동향을 정리하고, LWE-like 전자서명에 대한 고차 마스킹 기법 동향을 정리한다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.2
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• pp.149-156
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• 2011

In the recent years, power analysis attacks were widely investigated, and so various countermeasures have been proposed. In the case of block ciphers, masking methods that blind the intermediate values in the en/decryption computations are well-known among these countermeasures. But the cost of non-linear part is extremely high in the masking method of block cipher, and so the countermeasure for S-box must be efficiently constructed in the case of AES, ARIA and SEED. Existing countermeasures for S-box use the masked S-box table to require 256 bytes RAM corresponding to one S-box. But, the usage of the these countermeasures is not adequate in the lightweight security devices having the small size of RAM. In this paper, we propose the new countermeasure not using the masked S-box table to make up for this weak point. Also, the new countermeasure reduces time-complexity as well as the usage of RAM because this does not consume the time for generating masked S-box table.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.16 no.3
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• pp.143-155
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• 2006

ARIA is a 128-bit block cipher, which became a Korean Standard in 2004. According to recent research, this cipher is attacked by first order DPA attack. In this paper, we propose a new masking technique as a countermeasure against first order DPA attack and apply it to the ARIA. The proposed method is suitable for low memory environment. By using this countermeasure, we verified that it is secure against first order DPA attack. In addition, our method based on precomputation of inverse table can reduce the computational cost as increasing the number of S-BOX masking.