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Linear Redundancy in S-Boxes

  • Joanne Fuller
  • William Millan
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 2887)

Abstract

This paper reports the discovery of linear redundancy in the S-boxes of many ciphers recently proposed for standardisation (including Rijndael, the new AES). We introduce a new method to efficiently detect affine equivalence of Boolean functions, and hence we study the variety of equivalence classes existing in random and published S-boxes. This leads us to propose a new randomness criterion for these components. We present experimental data supporting the notion that linear redundancy is very rare in S-boxes with more than 6 inputs. Finally we discuss the impact this property may have on implementations, review the potential for new cryptanalytic attacks, and propose a new tweak for block ciphers that removes the redundancy. We also provide details of a highly nonlinear 8*8 non-redundant bijective S-box, which is suitable as a plug in replacement where required.

Keywords

Equivalence Class Boolean Function Block Cipher Algebraic Degree Algebraic Attack 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2003

Authors and Affiliations

  • Joanne Fuller
    • 1
  • William Millan
    • 1
  1. 1.Information Security Research CentreQueensland University of TechnologyBrisbaneAustralia

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