신명수, 홍석희, 성재철, 홍득조, 권동근, 김선엽, 김인성, 김선규, 신한범,

Vol. 34, No. 4, pp. 629-639, 8월. 2024
10.13089/JKIISC.2024.34.4.629, Full Text:
Keywords: ARX cipher, CHAM, superscalar architecture
Abstract

CHAM is designed with an emphasis on encryption speed, considering that in the ISO/IEC standard block cipher operation mode, encryption functions are used more often than decryption functions. In the superscalar architecture of modern general-purpose processors, different ordering of operations can lead to different processing speeds, even if the computation configuration is the same. In this paper, we analyze the implementation efficiency and security of CHAM-like structures, which rearrange the order of operations in the ARX-based block cipher CHAM, for single-block and parallel implementations in a general-purpose processor environment. The proposed structures are at least 9.3% and at most 56.4% efficient in terms of encryption speed. The security analysis evaluates the resistance of the CHAM-like structures to differential and linear attacks. In terms of security margin, the difference is 3.4% for differential attacks and 6.8% for linear attacks, indicating that the security strength is similar compared to the efficiency difference. These results can be utilized in the design of ARX-based block ciphers.

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