Differential Cryptanalysis of Q

  • Eli Biham
  • Vladimir Furman
  • Michal Misztal
  • Vincent Rijmen
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 2355)


Q is a block cipher based on Rijndael and Serpent, which was submitted as a candidate to the NESSIE project by Leslie McBride. The submission document of Q describes 12 one-round iterative characteristics with probability 2-18 each. On 7 rounds these characteristics have probability 2-126, and the author of Q claims that these are the best 7-round characteristics. We find additional one-round characteristics that can be extended to more rounds. We also combine the characteristics into differentials. We present several differential attacks on the full cipher. Our best attack on the full Q with 128-bit keys (8 rounds) uses 2105 chosen plaintexts and has a complexity of 277 encryptions. Our best attack on the full Q with larger key sizes (9 rounds) uses 2125 chosen ciphertexts, and has a complexity of 296 for 192-bit keys, and 2128 for 256-bit keys.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2002

Authors and Affiliations

  • Eli Biham
    • 1
  • Vladimir Furman
    • 1
  • Michal Misztal
    • 2
  • Vincent Rijmen
    • 3
  1. 1.Computer Science DepartmentTechnion — Israel Institute of TechnologyHaifaIsrael
  2. 2.Institute of Mathematics and Operational ResearchMilitary University of TechnologyWarsawPoland
  3. 3.ESAT/COSICK.U.LeuvenHeverleeBelgium

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