Cryptology ePrint Archive: Report 2020/285

Improved Security Bounds for Generalized Feistel Networks

Yaobin Shen and Chun Guo and Lei Wang

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 Feistel network 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.

Category / Keywords: secret-key cryptography / Block ciphers, Coupling, Tweakable block ciphers, Generalized Feistel networks, Provable security, Mode of operation

Original Publication (in the same form): IACR-FSE-2020

Date: received 4 Mar 2020

Contact author: yb_shen at sjtu edu cn

Available format(s): PDF | BibTeX Citation

Version: 20200306:084904 (All versions of this report)

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