An augmented family of cryptographic Parity Circuits

  • Kenji Koyama
  • Routo Terada
Part of the Lecture Notes in Computer Science book series (LNCS, volume 1396)


A computationally inexpensive involution called value dependent swapping is introduced. This involution is included in the non-linear cryptographic family of functions called Parity Circuits to increase its non-affineness and thus increase its strength against cryptanalysis. Our analysis shows that this augmented version of Parity Circuits still has fundamental cryptographic properties. The addition of this involution introduces a new type of randomization while preserving the invertibility of the functions being defined. We formulate affineness for a general function, and introduce a normalized non-affineness measure. We prove some non-affineness conditions for the augmented Parity Circuits, and evaluate their non-affineness. We suggest the value-dependent swapping can also be incorporated into DES-like cryptographic functions as well to make them stronger against cryptanalysis.


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Copyright information

© Springer-Verlag Berlin Heidelberg 1998

Authors and Affiliations

  • Kenji Koyama
    • 1
  • Routo Terada
    • 2
  1. 1.Nippon Telegraph and Telephone C.S. LabsSouraku-gun, KyotoJapan
  2. 2.University of S. PauloComputer Science Dept.Bra[sz]il

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