Meet-in-the-Middle Preimage Attack on Round-Reduced Areion256

Areion is a family of highly-efficient permutations proposed by Isobe et al. in the Annual Conference on Cryptographic Hardware and Embedded Systems (CHES) 2023, which is designed for short-(fixed)-input-length (SFIL) hash functions. In this paper, we study the preimage attack on Areion-DM, an SFIL hash function based on Areion permutation. Following the previous works of meet-in-the-middle (MITM) preimage attack, we proposed a new mixed integer linear programming-based automatic search model utilizing the linear combination of bytes from different chunks. We introduce a new attribute with new propagation rules, which could simplify the previous models. The new model reduces the number of variables and constraints of superposition technique. To search MITM attacks with lower memory, we add new constraints to limit the size of the stored list. We have identified new preimage attacks on 6-round and 5-round Areion256-DM. In the case of Areion256 without the final swap, our findings reveal novel preimage attacks on 7-round and 5-round configurations, demonstrating lower memory complexities compared to previous results.