On generalized bent functions with Dillon's exponents

  • Authors:
  • Samed Bajrić;Enes Pasalic;Amela Ribić-Muratović;Gangopadhyay Sugata

  • Affiliations:
  • University of Primorska, FAMNIT, Koper, Slovenia;University of Primorska, FAMNIT, Koper, Slovenia;University of Sarajevo, Sarajevo, Bosnia and Herzegovina;Department of Computer Science and Engineering, Indian Institute of Technology, Roorkee, India

  • Venue:
  • Information Processing Letters
  • Year:
  • 2014

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Abstract

In this paper we investigate the possibility of constructing bent functions over fields with odd characteristic. While in the binary case, and for n=2k, the bent property of monomials of the form Tr"1^n(ax^r^(^2^^^k^-^1^)) and binomials Tr"1^n(x^2^^^k^-^1+ax^r^(^2^^^k^-^1^)) were investigated in several papers, generalized bent functions f:GF(p^n)-GF(p) of the form Tr"1^n(@?"i"="1^ta"ix^r^"^i^(^p^^^k^-^1^)), p being an odd prime and n=2k, were not analyzed previously. In particular, the construction of vectorial (generalized) bent functions has not been addressed. It is shown that the necessary and sufficient bent conditions for both the single output function of the form f(x)=Tr"1^n(@?"i"="1^ta"ix^r^"^i^(^p^^^k^-^1^)) and the associated mapping F(x)=Tr"k^2^k(@?"i"="1^ta"ix^r^"^i^(^p^^^k^-^1^)), where F:GF(p^2^k)-GF(p^k), are very similar and can be expressed in terms of the image of a set V used in the direct sum decomposition of GF(p^2^k). Furthermore, it is observed that vectorial bent functions are easily constructed using the Maiorana-McFarland method.