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Security Proofs for Key-Alternating Ciphers with Non-Independent Round Permutations

Authors:
Liqing Yu , East China Normal University
Yusai Wu , Shanghai Qi Zhi Institute
Yu Yu , Shanghai Jiao Tong University
Zhenfu Cao , East China Normal University
Xiaolei Dong , East China Normal University
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Presentation: Slides
Conference: TCC 2023
Abstract: This work studies the key-alternating ciphers (KACs) whose round permutations are not necessarily independent. We revisit existing security proofs for key-alternating ciphers with a single permutation (KACSPs), and extend their method to an arbitrary number of rounds. In particular, we propose new techniques that can significantly simplify the proofs, and also remove two unnatural restrictions in the known security bound of 3-round KACSP (Wu et al., Asiacrypt 2020). With these techniques, we prove the first tight security bound for t-round KACSP, which was an open problem. We stress that our techniques apply to all variants of KACs with non-independent round permutations, as well as to the standard KACs.
BibTeX
@inproceedings{tcc-2023-33412,
  title={Security Proofs for Key-Alternating Ciphers with Non-Independent Round Permutations},
  publisher={Springer-Verlag},
  author={Liqing Yu and Yusai Wu and Yu Yu and Zhenfu Cao and Xiaolei Dong},
  year=2023
}