Paper 2014/279

Improved Impossible Differential Attacks against Round-Reduced LBlock

Christina Boura, Marine Minier, María Naya-Plasencia, and Valentin Suder


Impossible differential attacks are among the most powerful forms of cryptanalysis against block ciphers. We present in this paper an in-depth complexity analysis of these attacks. We show an unified way to mount such attacks and provide generic formulas for estimating their time, data and memory complexities. LBlock is a well studied lightweight block cipher with respect to impossible differential attacks. While previous single-key cryptanalysis reached up to 22 rounds, by applying our method we are able to break 23 rounds with time complexity $2^{75.36}$ and data complexity $2^{59}$. Other time/data trade-offs are equally possible. This is to our knowledge the best (non-exhaustive search like) cryptanalysis of this function in the single-key model.

Available format(s)
Secret-key cryptography
Publication info
Preprint. MINOR revision.
block ciphersimpossible differential attacksLBlock.
Contact author(s)
christina boura @ prism uvsq fr
2014-09-09: last of 4 revisions
2014-04-24: received
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Creative Commons Attribution


      author = {Christina Boura and Marine Minier and María Naya-Plasencia and Valentin Suder},
      title = {Improved Impossible Differential Attacks against Round-Reduced LBlock},
      howpublished = {Cryptology ePrint Archive, Paper 2014/279},
      year = {2014},
      note = {\url{}},
      url = {}
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