Paper 2018/332

Differential Cryptanalysis of Round-Reduced Sparx-64/128

Ralph Ankele and Eik List

Abstract

Sparx is a family of ARX-based block ciphers designed according to the long-trail strategy (LTS) that were both introduced by Dinu et al. at ASIACRYPT'16. Similar to the wide-trail strategy, the LTS allows provable upper bounds on the length of differential characteristics and linear paths. Thus, the cipher is a highly interesting target for third-party cryptanalysis. However, the only third-party cryptanalysis on Sparx-64/128 to date was given by Abdelkhalek et al. at AFRICACRYPT'17 who proposed impossible-differential attacks on 15 and 16 (out of 24) rounds. In this paper, we present chosen-ciphertext differential attacks on 16 rounds of Sparx-64/128. First, we show a truncated-differential analysis that requires $2^{32}$ chosen ciphertexts and approximately $2^{93}$ encryptions. Second, we illustrate the effectiveness of boomerangs on Sparx by a rectangle attack that requires approximately $2^{59.6}$ chosen ciphertexts and about $2^{122.2}$ encryption equivalents. Finally, we also considered a yoyo attack on 16 rounds that, however, requires the full codebook and approximately $2^{126}$ encryption equivalents.

Note: Fix non-math latex command in abstract

Metadata
Available format(s)
PDF
Publication info
Published elsewhere. MAJOR revision.ACNS 2018 Applied Cryptography & Network security
Keywords
Symmetric-key cryptographycryptanalysisboomerangtruncated differentialyoyoARX
Contact author(s)
ralph ankele 2015 @ live rhul ac uk
History
2018-04-10: received
Short URL
https://ia.cr/2018/332
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2018/332,
      author = {Ralph Ankele and Eik List},
      title = {Differential Cryptanalysis of Round-Reduced Sparx-64/128},
      howpublished = {Cryptology ePrint Archive, Paper 2018/332},
      year = {2018},
      note = {\url{https://eprint.iacr.org/2018/332}},
      url = {https://eprint.iacr.org/2018/332}
}
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