Improved Meet-in-the-Middle Distinguisher on Feistel Schemes

Li Lin; Wenling Wu

Paper 2015/051

Improved Meet-in-the-Middle Distinguisher on Feistel Schemes

Li Lin and Wenling Wu

Abstract

Improved meet-in-the-middle cryptanalysis with efficient tabulation technique has been shown to be a very powerful form of cryptanalysis against SPN block ciphers. However, few literatures show the effectiveness of this cryptanalysis against Balanced-Feistel-Networks (BFN) and Generalized-Feistel-Networks (GFN) ciphers due to the stagger of affected trail and special truncated differential trail. In this paper, we describe a versatile and powerful algorithm for searching the best improved meet-in-the-middle distinguisher with efficient tabulation technique on word-oriented BFN and GFN block ciphers, which is based on recursion and greedy algorithm. To demonstrate the usefulness of our approach, we show key recovery attacks on 14/16-round CLEFIA-192/256 which are the best attacks. We also propose key recovery attacks on 13/15-round Camellia-192/256 (without $FL/FL^{-1}$).

Metadata

Available format(s): PDF
Publication info: Preprint. MINOR revision.
Keywords: Block Ciphers Improved Meet-in-the-Middle Attack Efficient Tabulation Technique Automatic Search Tool Truncated Differential Trail CLEFIA Camellia.
Contact author(s): linli @ tca iscas ac cn
History: 2015-01-22: received
Short URL: https://ia.cr/2015/051
License: CC BY

BibTeX

@misc{cryptoeprint:2015/051,
      author = {Li Lin and Wenling Wu},
      title = {Improved Meet-in-the-Middle Distinguisher on Feistel Schemes},
      howpublished = {Cryptology {ePrint} Archive, Paper 2015/051},
      year = {2015},
      url = {https://eprint.iacr.org/2015/051}
}