Paper 2026/482

Cryptanalysis of Two Alternating Moduli Weak PRFs

Gregor Leander, Ruhr Bochum University

Håvard Raddum, Simula UiB

Arne Sandrib, University of Bergen

Aleksei Udovenko, University of Luxembourg

Abstract

In this work, we present new cryptanalytic attacks on recently proposed, theory-inspired constructions of weak pseudorandom functions (weak-PRFs). We demonstrate attacks on several such designs, showing that the initial security arguments require significant refinement. Methodologically, our approach relies on novel observations about the structure of cyclic matrices, applications of Wagner's generalized birthday technique, and conversion into polynomial systems over $\mathbb{F}_3$. These findings highlight the need for a more careful analysis of those weak-PRF candidates

@misc{cryptoeprint:2026/482,
      author = {Kai Hu and Gregor Leander and Håvard Raddum and Arne Sandrib and Aleksei Udovenko},
      title = {Cryptanalysis of Two Alternating Moduli Weak {PRFs}},
      howpublished = {Cryptology {ePrint} Archive, Paper 2026/482},
      year = {2026},
      url = {https://eprint.iacr.org/2026/482}
}