Improved Security Bounds for Generalized Feistel Networks

  • Yaobin Shen Department of Computer Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
  • Chun Guo Key Laboratory of Cryptologic Technology and Information Security of Ministry of Education, Shandong University, Qingdao, Shandong, 266237, China; School of Cyber Science and Technology, Shandong University, Qingdao, Shandong, China
  • Lei Wang Department of Computer Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
Keywords: Block ciphers, Coupling, Tweakable block ciphers, Generalized Feistel networks, Provable security, Mode of operation

Abstract

We revisit the security of various generalized Feistel networks. Concretely, for unbalanced, alternating, type-1, type-2, and type-3 Feistel networks built from random functions, we substantially improve the coupling analyzes of Hoang and Rogaway (CRYPTO 2010). For a tweakable blockcipher-based generalized Feistelnetwork proposed by Coron et al. (TCC 2010), we present a coupling analysis and for the first time show that with enough rounds, it achieves 2n-bit security, and this provides highly secure, double-length tweakable blockciphers.

Published
2020-05-07
How to Cite
Shen, Y., Guo, C., & Wang, L. (2020). Improved Security Bounds for Generalized Feistel Networks. IACR Transactions on Symmetric Cryptology, 2020(1), 425-457. https://doi.org/10.13154/tosc.v2020.i1.425-457
Section
Articles