Mixed Bases for Efficient Inversion in \({{\mathbb F}{((2^2)^2)}{2}}\) and Conversion Matrices of SubBytes of AES

  • Yasuyuki Nogami
  • Kenta Nekado
  • Tetsumi Toyota
  • Naoto Hongo
  • Yoshitaka Morikawa
Conference paper

DOI: 10.1007/978-3-642-15031-9_16

Part of the Lecture Notes in Computer Science book series (LNCS, volume 6225)
Cite this paper as:
Nogami Y., Nekado K., Toyota T., Hongo N., Morikawa Y. (2010) Mixed Bases for Efficient Inversion in \({{\mathbb F}{((2^2)^2)}{2}}\) and Conversion Matrices of SubBytes of AES. In: Mangard S., Standaert FX. (eds) Cryptographic Hardware and Embedded Systems, CHES 2010. CHES 2010. Lecture Notes in Computer Science, vol 6225. Springer, Berlin, Heidelberg

Abstract

A lot of improvements and optimizations for the hardware implementation of SubBytes of Rijndael, in detail inversion in \({\mathbb F}_{2^8}\) have been reported. Instead of the Rijndael original \({\mathbb F}_{2^8}\), it is known that its isomorphic tower field \({{\mathbb F}{((2^2)^2)}{2}}\) has a more efficient inversion. For the towerings, several kinds of bases such as polynomial and normal bases can be used in mixture. Different from the meaning of this mixture of bases, this paper proposes another mixture that contributes to the reduction of the critical path delay of SubBytes. To the \({{\mathbb F}{(2^2)}{2}}\)–inversion architecture, for example, the proposed mixture inputs and outputs elements represented with normal and polynomial bases, respectively.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2010

Authors and Affiliations

  • Yasuyuki Nogami
    • 1
  • Kenta Nekado
    • 1
  • Tetsumi Toyota
    • 1
  • Naoto Hongo
    • 1
  • Yoshitaka Morikawa
    • 1
  1. 1.Graduate School of Natural Science and TechnologyOkayama UniversityOkayamaJapan

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