The purpose of this talk is to introduce generic attacks based on functional graphs. Over the past ten years, the statistical properties of random functions have been particularly fruitful tool to mount generic attacks. Initially, these attacks targeted iterated hash constructions and their combiners, developing a wide array of methods based on internal collisions and on the average behavior of iterated random functions. More recently, we (Gilbert et al., EUROCRYPT 2023) introduced a forgery attack on so-called duplex-based Authenticated Encryption modes which is based on exceptional random functions, i.e., functions whose graph admits a large component with an exceptionally small cycle. We have since then improved this attack Bonnetain et al., CRYPTO 2024) using so-called nested exceptional functions. We also improved several attacks against hash combiners using exceptional random functions. This talk will present a variety of generic attacks based on functional graphs against hash functions, hash-based MACs and AEAD modes.
PhD student at Université Versailles Saint-Quentin-en-Yvelines working under the supervision of Christina Boura, Henri Gilbert and Yann Rotella.