International Association for Cryptologic Research

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Improved Differential Meet-In-The-Middle Cryptanalysis

Authors:
Zahra Ahmadian , Department of Electrical Engineering, Shahid Beheshti University, Tehran, Iran
Akram Khalesi , Department of Electrical Engineering, Shahid Beheshti University, Tehran, Iran
Dounia M'foukh , INRIA Paris
Hossein Moghimi , Department of Electrical Engineering, Shahid Beheshti University, Tehran, Iran
María Naya-Plasencia , INRIA Paris
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Conference: EUROCRYPT 2024
Abstract: In this paper, we extend the applicability of differential meet-in-the-middle attacks, proposed at Crypto 2023, to truncated differentials, and in addition, we introduce three new ideas to improve this type of attack: we show how to add longer structures than the original paper, we show how to improve the key recovery steps by introducing some probability in them, and we combine this type of attacks with the state-test technique, that was introduced in the context of impossible differential attacks. Furthermore, we have developed a MILP-based tool to automate the search for a truncated differential-MITM attack with optimized overall complexity, incorporating some of the proposed improvements. Thanks to this, we can build the best known attacks on the cipher CRAFT, reaching 23 rounds against 21 previously; we provide a new attack on 23 round SKINNY-64-192, and we improve the best attacks on SKINNY-128-384.
BibTeX
@inproceedings{eurocrypt-2024-33999,
  title={Improved Differential Meet-In-The-Middle Cryptanalysis},
  publisher={Springer-Verlag},
  author={Zahra Ahmadian and Akram Khalesi and Dounia M'foukh and Hossein Moghimi and María Naya-Plasencia},
  year=2024
}