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Generic Attack on Duplex-Based AEAD Modes using Random Function Statistics

Authors:
Henri Gilbert , ANSSI, France
Rachelle Heim Boissier , Université Paris-Saclay, UVSQ, CNRS, Laboratoire de mathématiques de Versailles, 78000, Versailles, France
Louiza Khati , ANSSI, France
Yann Rotella , Université Paris-Saclay, UVSQ, CNRS, Laboratoire de mathématiques de Versailles, 78000, Versailles, France
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DOI: 10.1007/978-3-031-30634-1_12 (login may be required)
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Presentation: Slides
Conference: EUROCRYPT 2023
Abstract: Duplex-based authenticated encryption modes with a sufficiently large key length are proven to be secure up to the birthday bound 2^(c/2), where c is the capacity. However this bound is not known to be tight and the complexity of the best known generic attack, that is based on multicollisions, is much larger: it reaches (2^c)/α where α represents a small security loss factor. There is thus an uncertainty on the true extent of security beyond the bound 2^(c/2) provided by such constructions. In this paper, we describe a new generic attack against several duplex-based AEAD modes. Our attack produces a forgery in time complexity O(2^(3c/4)) using negligible memory and no encryption queries. Furthermore, for some duplex-based modes, our attack also recovers the secret key with a negligible amount of additional computations. Most notably, our attack breaks a security claim made by the designers of the NIST lightweight competition candidate Xoodyak. This attack is a step further towards determining the exact security provided by duplex-based constructions.
BibTeX
@inproceedings{eurocrypt-2023-32887,
  title={Generic Attack on Duplex-Based AEAD Modes using Random Function Statistics},
  publisher={Springer-Verlag},
  doi={10.1007/978-3-031-30634-1_12},
  author={Henri Gilbert and Rachelle Heim Boissier and Louiza Khati and Yann Rotella},
  year=2023
}