Cheng Che
Information Engineering University, Zhengzhou, China

Tian Tian
Information Engineering University, Zhengzhou, China

Keywords: ChiLow, Differential-Linear Cryptanalysis, Cube Attack, MILP

Abstract

ChiLow is a family of tweakable block ciphers specifically designed for embedded code encryption and was proposed at EUROCRYPT 2025. Its nested tweak-key schedule and chi-based design significantly improve latency and energy efficiency. This paper studies ChiLow from the perspectives of differential-linear cryptanalysis and cube attacks, filling gaps in the original security analysis. The main contributions are threefold: distinguishing attacks based on differential-linear cryptanalysis that can distinguish full-round ChiLow from random permutations; key-recovery attacks on full-round ChiLow based on differential-linear cryptanalysis with time complexity better than exhaustive search; and a key-recovery attack on 6-round ChiLow based on cube attacks. These results shed new light on the security boundaries of ChiLow and provide useful insights for the design of low-latency ciphers for embedded systems.