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Cryptanalysis of Achterbahn-Version 2

  • Martin Hell
  • Thomas Johansson
Part of the Lecture Notes in Computer Science book series (LNCS, volume 4356)

Abstract

Achterbahn is one of the stream cipher proposals in the eSTREAM project. After the first version had been successfully cryptanalyzed, the second version, denoted Achterbahn-Version 2, was proposed. This paper demonstrates an attack on this second version. In the attack, a quadratic approximation of the output function is considered. The attack uses less keystream bits than the upper limit given by the designers and the computational complexity is significantly less than exhaustive key search.

Keywords

Achterbahn cryptanalysis stream ciphers key recovery attack 

References

  1. 1.
    ECRYPT. eSTREAM: ECRYPT Stream Cipher Project, IST-2002-507932. Available at http://www.ecrypt.eu.org/stream/
  2. 2.
    Gammel, B.M., Göttfert, R., Kniffler, O.: The Achterbahn stream cipher. eSTREAM, ECRYPT Stream Cipher Project, Report 2005/002 (2005), http://www.ecrypt.eu.org/stream
  3. 3.
    Gammel, B.M., Göttfert, R., Kniffler, O.: Improved Boolean combining functions for Achterbahn. eSTREAM, ECRYPT Stream Cipher Project, Report 2005/072 (2005), http://www.ecrypt.eu.org/stream
  4. 4.
    Gammel, B.M., Göttfert, R., Kniffler, O.: Status of Achterbahn and tweaks. The State of the Art of Stream Ciphers. In: Workshop Record, SASC 2006, Leuven, Belgium (February 2006)Google Scholar
  5. 5.
    Johansson, T., Meier, W., Müller, F.: Cryptanalysis of Achterbahn. eSTREAM, ECRYPT Stream Cipher Project, Report 2005/064 (2005), http://www.ecrypt.eu.org/stream
  6. 6.
    Johansson, T., Meier, W., Müller, F.: Cryptanalysis of Achterbahn. In: Robshaw, M. (ed.) FSE 2006. LNCS, vol. 4047, Springer, Heidelberg (2006)CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2007

Authors and Affiliations

  • Martin Hell
    • 1
  • Thomas Johansson
    • 1
  1. 1.Dept. of Information Technology, Lund University, P.O. Box 118, 221 00 LundSweden

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