Paper 2015/861

A Synthetic Indifferentiability Analysis of Interleaved Double-Key Even-Mansour Ciphers

Chun Guo and Dongdai Lin

Abstract

Iterated Even-Mansour scheme (IEM) is a generalization of the basic 1-round proposal (ASIACRYPT '91). The scheme can use one key, two keys, or completely independent keys. Most of the published security proofs for IEM against relate-key and chosen-key attacks focus on the case where all the round-keys are derived from a single master key. Whereas results beyond this barrier are relevant to the cryptographic problem whether a secure blockcipher with key-size twice the block-size can be built by mixing two \emph{relatively independent} keys into IEM and iterating sufficiently many rounds, and this strategy actually has been used in designing blockciphers for a long-time. This work makes the first step towards breaking this barrier and considers IEM with Interleaved Double \emph{independent} round-keys: where when is odd, and when is even. As results, this work proves that 15 rounds can achieve (full) indifferentiability from an ideal cipher with security bound. This work also proves that 7 rounds is sufficient and necessary to achieve sequential-indifferentiability (a notion introduced at TCC 2012) with security bound, so that is already correlation intractable and secure against any attack that exploits evasive relations between its input-output pairs.

Metadata
Available format(s)
PDF
Publication info
A major revision of an IACR publication in ASIACRYPT 2015
Keywords
blockcipherideal cipherindifferentiabilitykey-alternating cipherEven-Mansour ciphercorrelation intractability.
Contact author(s)
guochun @ iie ac cn
History
2015-09-06: received
Short URL
https://ia.cr/2015/861
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2015/861,
      author = {Chun Guo and Dongdai Lin},
      title = {A Synthetic Indifferentiability Analysis of Interleaved Double-Key Even-Mansour Ciphers},
      howpublished = {Cryptology {ePrint} Archive, Paper 2015/861},
      year = {2015},
      url = {https://eprint.iacr.org/2015/861}
}
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