Paper 2019/126

New Automatic search method for Truncated-differential characteristics: Application to Midori, SKINNY and CRAFT

AmirHossein E. Moghaddam and Zahra Ahmadian

Abstract

In this paper, using Mixed Integer Linear Programming, a new automatic search tool for truncated differential characteristic is presented. Our method models the problem of finding a maximal probability truncated differential characteristic, which is able to distinguish the cipher from a pseudo random permutation. Using this method, we analyse Midori64, SKINNY64/X and CRAFT block ciphers, for all of which the existing results are improved. In all cases, the truncated differential characteristic is much more efficient than the (upper bound of) bit-wise differential characteristic proven by the designers, for any number of rounds. More specifically, the highest possible rounds, for which an efficient differential characteristic can exist for Midori64, SKINNY64/X and CRAFT are 6, 7 and 10 rounds respectively, for which differential characteristics with maximum probabilities of $2^{-60}$, $2^{-52}$ and $2^{-62.61}$ (may) exist. Using our new method, we introduce new truncated differential characteristics for these ciphers with respective probabilities $2^{-54}$, $2^{-4}$ and $2^{-24}$ at the same number of rounds. Moreover, the longest truncated differential characteristics found for SKINNY64/X and CRAFT have 10 and 12 rounds, respectively. This method can be used as a new tool for differential analysis of SPN block ciphers.

Metadata
Available format(s)
PDF
Category
Secret-key cryptography
Publication info
Preprint.
Keywords
Truncated DifferentialMILPSPN
Contact author(s)
zahraahmadian @ yahoo com
History
2019-06-09: last of 2 revisions
2019-02-13: received
See all versions
Short URL
https://ia.cr/2019/126
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2019/126,
      author = {AmirHossein E.  Moghaddam and Zahra Ahmadian},
      title = {New Automatic search method for Truncated-differential characteristics: Application to Midori, SKINNY and CRAFT},
      howpublished = {Cryptology ePrint Archive, Paper 2019/126},
      year = {2019},
      note = {\url{https://eprint.iacr.org/2019/126}},
      url = {https://eprint.iacr.org/2019/126}
}
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