Improved meet-in-the-middle collision attack on round-reduced Xoodyak

Abstract With the growing prevalence of compact and resource-constrained computing devices, demand for lightweight cryptographic schemes is burgeoning. , a lightweight hash function that entered the final round of the NIST Lightweight Cryptography (LWC), has received extensive attention owing to its security and high efficiency. Meet-in-the-Middle (MitM) attack serves as an effective method for the analysis of sponge-based hashing. Nevertheless, constrained by the large search space, the optimization of MitM attack remains to be further investigated. We introduce an improved approach, overall-weak-diffusion structure searching strategy, to identify a weak diffusion neutral set in the heuristic two-stage searching strategy, and apply it to 3-round . Ultimately, the time complexity of MitM collision attack against 3-round is reduced to $$2^{124.24}$$ 2 124.24