New results on the quantum security analysis of lightweight block cipher Simeck

Abstract

Simeck demonstrates reliable resistance against conventional cryptanalytic attacks and offers sound security properties, making it a noteworthy design in the field of lightweight cryptography. Nevertheless, ongoing progress in quantum computing poses a potential threat to the security of Simeck, underscoring the need for a rigorous analysis of its quantum resilience. In this paper, we analyze quantum distinguishers and key-recovery attacks on Simeck in the Q2 model. Leveraging the connection between truncated differentials and periodic functions, we revisit Simon-type qCPA distinguishers for Simeck-32/48/64 and further extend them to the qCCA setting. The qCPA distinguishers cover 8/9/11 rounds of Simeck-32/48/64, matching the round numbers reported by Lu et al. (2026), whereas our qCCA distinguishers cover 10/11/13 rounds. Based on these distinguishers, we investigate their application to Grover-meets-Simon key-recovery attacks on reduced-round Simeck. Furthermore, we mount qCPA key-recovery attacks on 11/12/14-round Simeck-32/48/64 and extend them to qCCA attacks on 13/14/16-round Simeck-32/48/64. Finally, we provide empirical estimates of the quantum resources required for the proposed key-recovery attacks. For Simeck-32/48/64, the empirical quantum query complexities are 228.09/240.32/252.59\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$2^{28.09}/2^{40.32}/2^{52.59}$$\end{document} in the qCPA setting and 226.81/239/251.17\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$2^{26.81}/2^{39}/2^{51.17}$$\end{document} in the qCCA setting, respectively, under the stated decision-test assumptions and empirical false-positive estimates.