A New Approach for FCSRs

  • Franc̨ois Arnault
  • Thierry Berger
  • Cédric Lauradoux
  • Marine Minier
  • Benjamin Pousse
Part of the Lecture Notes in Computer Science book series (LNCS, volume 5867)


The Feedback with Carry Shift Registers (FCSRs) have been proposed as an alternative to Linear Feedback Shift Registers (LFSRs) for the design of stream ciphers. FCSRs have good statistical properties and they provide a built-in non-linearity. However, two attacks have shown that the current representations of FCSRs can introduce weaknesses in the cipher. We propose a new “ring” representation of FCSRs based upon matrix definition which generalizes the Galois and Fibonacci representations. Our approach preserves the statistical properties and circumvents the weaknesses of the Fibonacci and Galois representations. Moreover, the ring representation leads to automata with a quicker diffusion characteristic and better implementation results. As an application, we describe a new version of F-FCSR stream ciphers.


Stream cipher FCSRs ℓ-sequence ring FCSRs 


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Copyright information

© Springer-Verlag Berlin Heidelberg 2009

Authors and Affiliations

  • Franc̨ois Arnault
    • 1
  • Thierry Berger
    • 1
  • Cédric Lauradoux
    • 2
  • Marine Minier
    • 3
  • Benjamin Pousse
    • 1
  1. 1.XLIM (UMR CNRS 6172)Université de LimogesLimoges CedexFrance
  2. 2.Information Security GroupUCL / INGI / GSILouvain-la-NeuveBelgium
  3. 3.CITI Laboratory - INSA de LyonLyon UniversityVilleurbanne CedexFrance

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