Improved Conditional Cube Attacks on Ascon AEADs in Nonce-Respecting Settings

with a Break-Fix Strategy


  • Kai Hu School of Cyber Science and Technology, Shandong University, Qingdao, Shandong, China; School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore; Key Laboratory of Cryptologic Technology and Information Security, Ministry of Education, Shandong University, Jinan, China



Ascon, AEAD, Conditional Cube Attack


The best-known distinguisher on 7-round Ascon-128 and Ascon-128a AEAD uses a 60-dimensional cube where the nonce bits are set to be equal in the third and fourth rows of the Ascon state during initialization (Rohit et al. ToSC 2021/1). It was not known how to use this distinguisher to mount key-recovery attacks. In this paper, we investigate this problem using a new strategy called break-fix for the conditional cube attack. The idea is to introduce slightly-modified cubes which increase the degrees of 7-round output bits to be more than 59 (break phase) and then find key conditions which can bring the degree back to 59 (fix phase). Using this idea, key-recovery attacks on 7-round Ascon-128, Ascon-128a and Ascon-80pq are proposed. The attacks have better time/memory complexities than the existing attacks, and in some cases improve the weak-key attacks as well.







How to Cite

Improved Conditional Cube Attacks on Ascon AEADs in Nonce-Respecting Settings: with a Break-Fix Strategy. (2024). IACR Transactions on Symmetric Cryptology, 2024(2), 118-140.