Recently, the research achievement titled "Unlocking Mix-Basis Potential: Geometric Approach for Combined Attacks" by Professor Wang Meiqin's team from the School of Cyber Science and Technology has been accepted by CRYPTO 2025 — a pinnacle conference in cryptography. Research Professor Hu Kai is the first author of the paper, with Professor Wang as the corresponding author. This work was conducted in collaboration with both the research team from Shandong University and Professor Thomas Peyrin from Nanyang Technological University.

Fig. 1: The process of generating the transition matrix under a pair of different bases

The geometric approach for symmetric cryptanalysis, first pioneered by Tim Beyne at ASIACRYPT 2021, introduced a novel mathematical toolkit to analyze cryptographic algorithms, offering a new perspective for cryptanalytic theory. Prof. Wang Meiqin’s team has delved into advancing this framework, specifically exploring the potential of employing different bases within geometric methods. Their development of mix-basis geometric techniques has significantly enhanced the methodology’s flexibility. Building on this theory, the team refined the ultrametric integral analysis proposed by Beyne and Verbauwhede, unifying the application of ultrametric properties with other geometric tools. Moreover, leveraging their innovative framework, they discovered a new multiple-of-2t distinguisher for the SKINNY-64 algorithm, outperforming previous state-of-the-art results. Finally, the research established closed-form expressions for differential-linear approximations without relying on heuristic assumptions. Notably, they confirmed that two differential-linear approximations for SIMECK-32 and SIMECK-48 (originally proposed by Hadipour et al.) are deterministic — their validity holds independent of specific key values.

CRYPTO (International Cryptology Conference) is organized by IACR. Alongside EUROCRYPT and ASIACRYPT, it ranks among cryptography's top three global conferences, representing the field's highest research level and wielding significant international influence.

Prof. Wang Meiqin has been actively engaged in the analysis of symmetric cryptographic algorithms for years, specializing in pinpointing vulnerabilities within cryptographic systems to strengthen security protocols and foster robust cybersecurity ecosystems. Her team has made groundbreaking contributions to this field, with findings extensively published at leading cryptography conferences including EUROCRYPT, ASIACRYPT and FSE/ToSC.

By Hu Kai and Xiao Anqi