# The connection between quadratic bent–negabent functions and the Kerdock code

• Pantelimon Stănică
• Bimal Mandal
• Subhamoy Maitra
Original Paper

## Abstract

In this paper we prove that all bent functions in the Kerdock code, except for the coset of the symmetric quadratic bent function, are bent–negabent. In this direction, we characterize the set of quadratic bent–negabent functions and show some results connecting quadratic bent–negabent functions and the Kerdock code. Further, we note that there are bent–negabent preserving nonsingular transformations outside the well known class of orthogonal ones that might provide additional functions in the bent–negabent set. This is the first time we could identify non-orthogonal (nonsingular) linear transformations that preserve bent–negabent property for a special subset.

## Keywords

Boolean function Bent function Negabent function Kerdock code

## Notes

### Acknowledgements

The authors would like to thank the reviewers for extraordinarily useful criticisms and suggestions, and for providing us with a better code of Fig. 1. The paper was partly written while the first author visited the second and third authors at the Indian Statistical Institute, Kolkata. He would like to thank the hosts and the institute for hospitality and excellent working conditions.

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© This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply 2019

## Authors and Affiliations

• Pantelimon Stănică
• 1
• Bimal Mandal
• 2
• Subhamoy Maitra
• 3
1. 1.Department of Applied MathematicsNaval Postgraduate SchoolMontereyUSA
2. 2.R. C. Bose Centre for Security and Cryptology, Indian Statistical InstituteKolkataIndia
3. 3.Applied Statistics UnitIndian Statistical InstituteKolkataIndia