Ciphertext only Reconstruction of Stream Ciphers Based on Combination Generators

  • Anne Canteaut
  • Eric Filiol
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 1978)


This paper presents an operational reconstruction technique of most stream ciphers. We primarily expose it for key-stream generators which consist of several linear feedback shift registers combined by a nonlinear Boolean function. It is shown how to completely recover the different feedback polynomials and the combining function, when the algorithm is totally unknown. This attack only requires the knowledge of some ciphertexts, which may be generated from different secret keys. Estimates of necessary ciphertext length and experimental results are detailed.


stream cipher Boolean function correlation linear feedback shift register ciphertext only reconstruction 


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Copyright information

© Springer-Verlag Berlin Heidelberg 2001

Authors and Affiliations

  • Anne Canteaut
    • 1
  • Eric Filiol
    • 1
    • 2
  1. 1.projet CODESINRIALe Chesnay CedexFRANCE
  2. 2.Ecoles militaires de Saint-Cyr CoëtquidanDGER/CRECSC/DSIGuer CedexFRANCE

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