Paper 2015/051

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

Li Lin and Wenling Wu


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 $FL/FL^{-1}$).

Available format(s)
Publication info
Preprint. MINOR revision.
Block CiphersImproved Meet-in-the-Middle AttackEfficient Tabulation TechniqueAutomatic Search ToolTruncated Differential TrailCLEFIACamellia.
Contact author(s)
linli @ tca iscas ac cn
2015-01-22: received
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Creative Commons Attribution


      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},
      note = {\url{}},
      url = {}
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