Several classes of bent functions over finite fields

08/02/2021

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by   Xi Xie, et al.

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Let 𝔽_p^n be the finite field with p^n elements and Tr(·) be the trace function from 𝔽_p^n to 𝔽_p, where p is a prime and n is an integer. Inspired by the works of Mesnager (IEEE Trans. Inf. Theory 60(7): 4397-4407, 2014) and Tang et al. (IEEE Trans. Inf. Theory 63(10): 6149-6157, 2017), we study a class of bent functions of the form f(x)=g(x)+F(Tr(u_1x),Tr(u_2x),⋯,Tr(u_τx)), where g(x) is a function from 𝔽_p^n to 𝔽_p, τ≥2 is an integer, F(x_1,⋯,x_n) is a reduced polynomial in 𝔽_p[x_1,⋯,x_n] and u_i∈𝔽^*_p^n for 1≤ i ≤τ. As a consequence, we obtain a generic result on the Walsh transform of f(x) and characterize the bentness of f(x) when g(x) is bent for p=2 and p>2 respectively. Our results generalize some earlier works. In addition, we study the construction of bent functions f(x) when g(x) is not bent for the first time and present a class of bent functions from non-bent Gold functions.