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Security of Symmetric Primitives against Key-Correlated Attacks

Authors:
Aisling Connolly , Ingenico Group, Paris, France; Département d’informatique École normale supérieure (DIENS), Centre national de la recherche scientifique (CNRS), Université Paris Sciences et Lettres (PSL), Paris, France
Pooya Farshim , Département d’informatique École normale supérieure (DIENS), Centre national de la recherche scientifique (CNRS), Université Paris Sciences et Lettres (PSL), Paris, France; Inria, Paris, France
Georg Fuchsbauer , Département d’informatique École normale supérieure (DIENS), Centre national de la recherche scientifique (CNRS), Université Paris Sciences et Lettres (PSL), Paris, France; Inria, Paris, France
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DOI: 10.13154/tosc.v2019.i3.193-230
URL: https://tosc.iacr.org/index.php/ToSC/article/view/8363
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Abstract: We study the security of symmetric primitives against key-correlated attacks (KCA), whereby an adversary can arbitrarily correlate keys, messages, and ciphertexts. Security against KCA is required whenever a primitive should securely encrypt key-dependent data, even when it is used under related keys. KCA is a strengthening of the previously considered notions of related-key attack (RKA) and key-dependent message (KDM) security. This strengthening is strict, as we show that 2-round Even–Mansour fails to be KCA secure even though it is both RKA and KDM secure. We provide feasibility results in the ideal-cipher model for KCAs and show that 3-round Even–Mansour is KCA secure under key offsets in the random-permutation model. We also give a natural transformation that converts any authenticated encryption scheme to a KCA-secure one in the random-oracle model. Conceptually, our results allow for a unified treatment of RKA and KDM security in idealized models of computation.
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BibTeX
@article{tosc-2019-29949,
  title={Security of Symmetric Primitives against Key-Correlated Attacks},
  journal={IACR Transactions on Symmetric Cryptology},
  publisher={Ruhr-Universität Bochum},
  volume={2019, Issue 3},
  pages={193-230},
  url={https://tosc.iacr.org/index.php/ToSC/article/view/8363},
  doi={10.13154/tosc.v2019.i3.193-230},
  author={Aisling Connolly and Pooya Farshim and Georg Fuchsbauer},
  year=2019
}