Hyperbent Functions via Dillon-Like Exponents

This paper is devoted to hyperbent functions with multiple trace terms (including binomial functions) via Dillon-like exponents. We show how the approach developed by Mesnager to extend the Charpin–Gong family, which was also used by Wang and coworkers to obtain another similar extension, fits in a much more general setting. To this end, we first explain how the original restriction for Charpin–Gong criterion can be weakened before generalizing the Mesnager approach to arbitrary Dillon-like exponents. Afterward, we tackle the problem of devising infinite families of extension degrees for which a given exponent is valid and apply these results not only to reprove straightforwardly the results of Mesnager and Wang and coworkers, but also to characterize the hyperbentness of several new infinite classes of Boolean functions. We go into full details only for a few of them, but provide an algorithm (and the corresponding software) to apply this approach to an infinity of other new families. Finally, we compare the asymptotic and practical performances of different characterizations, including these in terms of hyperelliptic curves, and actually build hyperbent functions in cases which could not be attained through naive computations of exponential sums.