### SAND: an AND-RX Feistel lightweight block cipher supporting S-box-based security evaluations

Shiyao Chen, Yanhong Fan, Ling Sun, Yong Fu, Haibo Zhou, Yongqing Li, Meiqin Wang, Weijia Wang, and Chun Guo

##### Abstract

We revisit designing AND-RX block ciphers, that is, the designs assembled with the most fundamental binary operations---AND, Rotation and XOR operations and do not rely on existing units. Likely, the most popular representative is the NSA cipher \texttt{SIMON}, which remains one of the most efficient designs, but suffers from difficulty in security evaluation. As our main contribution, we propose \texttt{SAND}, a new family of lightweight AND-RX block ciphers. To overcome the difficulty regarding security evaluation, \texttt{SAND} follows a novel design approach, the core idea of which is to restrain the AND-RX operations to be within nibbles. By this, \texttt{SAND} admits an equivalent representation based on a $4\times8$ \textit{synthetic S-box} ($SSb$). This enables the use of classical S-box-based security evaluation approaches. Consequently, for all versions of \texttt{SAND}, (a) we evaluated security bounds with respect to differential and linear attacks, and in both single-key and related-key scenarios; (b) we also evaluated security against impossible differential and zero-correlation linear attacks. This better understanding of the security enables the use of a relatively simple key schedule, which makes the ASIC round-based hardware implementation of \texttt{SAND} to be one of the state-of-art Feistel lightweight ciphers. As to software performance, due to the natural bitslice structure, \texttt{SAND} reaches the same level of performance as \texttt{SIMON} and is among the most software-efficient block ciphers.

Available format(s)
Category
Secret-key cryptography
Publication info
Published elsewhere. Design, Codes and Cryptography 2021
DOI
10.1007/s10623-021-00970-9
Keywords
Lightweight cryptographyFeistel structureAND-Rotation-XORSynthetic S-boxRelated-key security
Contact author(s)
mqwang @ sdu edu cn
sychen @ mail sdu edu cn
History
Short URL
https://ia.cr/2021/1560

CC BY

BibTeX

@misc{cryptoeprint:2021/1560,
author = {Shiyao Chen and Yanhong Fan and Ling Sun and Yong Fu and Haibo Zhou and Yongqing Li and Meiqin Wang and Weijia Wang and Chun Guo},
title = {SAND: an AND-RX Feistel lightweight block cipher supporting S-box-based security evaluations},
howpublished = {Cryptology ePrint Archive, Paper 2021/1560},
year = {2021},
doi = {10.1007/s10623-021-00970-9},
note = {\url{https://eprint.iacr.org/2021/1560}},
url = {https://eprint.iacr.org/2021/1560}
}

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