Vectorial Hyperbent Trace Functions From the \(\mathcal {PS}_{\rm ap}\) Class—Their Exact Number and Specification

Autor: Enes Pasalic, Amela Muratovic-Ribic, Samir Ribic
Rok vydání: 2014
Předmět:
Zdroj: IEEE Transactions on Information Theory. 60:4408-4413
ISSN: 1557-9654
0018-9448
DOI: 10.1109/tit.2014.2320269
Popis: To identify and specify trace bent functions of the form \(Tr(P(x))\) , where \(P(x) \in {\mathbb F} _{2^n}[x]\) , has been an important research topic lately. We characterize a class of vectorial (hyper)bent functions of the form \(F(x)=Tr_k^n(\sum _{i=0}^{2^k}a_ix^{i(2^k-1)})\) , where \(n=2k\) , in terms of finding an explicit expression for the coefficients \(a_i\) so that \(F\) is vectorial hyperbent. These coefficients only depend on the choice of the interpolating polynomial used in the Lagrange interpolation of the elements of \(\mathcal {U}\) and some prespecified outputs, where \(\mathcal {U}\) is the cyclic group of \((2^{n/2}+1)\) th roots of unity in \( {\mathbb F}_{2^n}\) . We show that these interpolation polynomials can be chosen in exactly \((2^k+1)!2^{k-1}\) ways and this is the exact number of vectorial hyperbent functions of the form \(Tr^n_k(\sum _{i=0}^{2^k}a_ix^{i(2^k-1)})\) . Furthermore, a simple optimization method is proposed for selecting the interpolation polynomials that give rise to trace polynomials with a few nonzero coefficients.
Databáze: OpenAIRE