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

Liqing Yu; Yusai Wu; Yu Yu; Zhenfu Cao; Xiaolei Dong

Paper 2023/1355

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

Liqing Yu, East China Normal University, Shanghai Qi Zhi Institute

Yusai Wu, Shanghai Qi Zhi Institute

Yu Yu

, Shanghai Jiao Tong University, Shanghai Qi Zhi Institute

Zhenfu Cao

, East China Normal University

Xiaolei Dong, East China Normal University

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.

Metadata

Available format(s): PDF
Category: Secret-key cryptography
Publication info: A major revision of an IACR publication in TCC 2023
Keywords: provable security key-alternating cipher KACSP indistinguishability random permutation model non-independent
Contact author(s): lqyups @ 126 com
yusaiwu @ 126 com
yuyu @ yuyu hk
zfcao @ sei ecnu edu cn
dong-xl @ sei ecnu edu cn
History: 2023-09-13: approved; 2023-09-11: received; See all versions
Short URL: https://ia.cr/2023/1355
License: CC BY

BibTeX

@misc{cryptoeprint:2023/1355,
      author = {Liqing Yu and Yusai Wu and Yu Yu and Zhenfu Cao and Xiaolei Dong},
      title = {Security Proofs for Key-Alternating Ciphers with Non-Independent Round Permutations},
      howpublished = {Cryptology {ePrint} Archive, Paper 2023/1355},
      year = {2023},
      url = {https://eprint.iacr.org/2023/1355}
}