Paper 2014/320

Improved Differential Cryptanalysis of Round-Reduced Speck

Itai Dinur

Abstract

Simon and Speck are families of lightweight block ciphers designed by the U.S. National Security Agency and published in 2013. Each of the families contains 10 variants, supporting a wide range of block and key sizes. Since the publication of Simon and Speck, several research papers analyzed their security using various cryptanalytic techniques. The best previously published attacks on all the 20 round-reduced ciphers are differential attacks, and are described in two papers (presented at FSE 2014) by Abed et al. and Biryukov et al. In this paper, we focus on the software-optimized block cipher family Speck, and describe significantly improved attacks on all of its 10 variants. In particular, we increase the number of rounds which can be attacked by 1, 2, or 3, for 9 out of 10 round-reduced members of the family, while significantly improving the complexity of the previous best attack on the remaining round-reduced member. Our attacks use an untraditional key recovery technique for differential attacks, whose main ideas were published by Albrecht and Cid at FSE 2009 in the cryptanalysis of the block cipher PRESENT. Despite our improved attacks, they do not seem to threaten the security of any member of Speck.

Metadata
Available format(s)
PDF
Category
Secret-key cryptography
Publication info
Published elsewhere. MINOR revision.SAC 2014
Keywords
Lightweight block cipherSpeckcryptanalysisdifferential attackkey recovery
Contact author(s)
dinur @ di ens fr
History
2014-08-31: last of 2 revisions
2014-05-06: received
See all versions
Short URL
https://ia.cr/2014/320
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2014/320,
      author = {Itai Dinur},
      title = {Improved Differential Cryptanalysis of Round-Reduced Speck},
      howpublished = {Cryptology ePrint Archive, Paper 2014/320},
      year = {2014},
      note = {\url{https://eprint.iacr.org/2014/320}},
      url = {https://eprint.iacr.org/2014/320}
}
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