Improved differential cryptanalysis of round-reduced speck

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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.

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 roundreduced ciphers are differential attacks, and are described in two papers (presented at FSE 2014) by Abed et al. and Biryukov et al.

Despite our improved attacks, they do not seem to threaten the security of any member of Speck.

Original languageEnglish
Title of host publicationSelected Areas in Cryptography - SAC 2014 - 21st International Conference, Revised Selected Papers
EditorsAntoine Joux, Amr Youssef
PublisherSpringer Verlag
Number of pages18
ISBN (Electronic)9783319130507
StatePublished - 1 Jan 2014
Externally publishedYes
Event21st International Conference on Selected Areas in Cryptography, SAC 2014 - Montreal, Canada
Duration: 14 Aug 201415 Aug 2014

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


Conference21st International Conference on Selected Areas in Cryptography, SAC 2014


  • Cryptanalysis
  • Differential attack
  • Key recovery
  • Lightweight block cipher
  • Speck


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