A vectorial Boolean function $F\colon\mathbb F_2^n\to\mathbb F_2^n$ is called almost perfect nonlinear (APN) if the equation $F(x)+F(x+a)=b$ has at most $2$ solutions for all vectors $a,b\in\mathbb F_2^n$, where $a$ is nonzero. For a given $F$, an associated Boolean function $\gamma_F(a,b)$ in $2n$ variables is defined so that it takes value $1$ iff $a$ is nonzero and the equation $F(x)+F(x+a)=b$ has solutions. We introduce the notion of differentially equivalent functions as vectorial functions that have equal associated Boolean functions. The problem to describe the differential equivalence class of a given APN function is very interesting since the answer can potentially lead to some new constructions of APN functions. We start analyzing this problem with the consideration of affine functions $A$ such that a quadratic APN function $F$ and $F+A$ are differentially equivalent functions. We completely describe these affine functions $A$ for an arbitrary APN Gold function $F$. Computational results for known quadratic APN functions in small number of variables $(2,\dots,8)$ are presented.
@article{PDMA_2016_9_a7,
author = {A. A. Gorodilova},
title = {On differential equivalence of quadratic {APN} functions},
journal = {Prikladnaya Diskretnaya Matematika. Supplement},
pages = {21--24},
year = {2016},
number = {9},
language = {ru},
url = {http://geodesic.mathdoc.fr/item/PDMA_2016_9_a7/}
}
TY - JOUR
AU - A. A. Gorodilova
TI - On differential equivalence of quadratic APN functions
JO - Prikladnaya Diskretnaya Matematika. Supplement
PY - 2016
SP - 21
EP - 24
IS - 9
UR - http://geodesic.mathdoc.fr/item/PDMA_2016_9_a7/
LA - ru
ID - PDMA_2016_9_a7
ER -
%0 Journal Article
%A A. A. Gorodilova
%T On differential equivalence of quadratic APN functions
%J Prikladnaya Diskretnaya Matematika. Supplement
%D 2016
%P 21-24
%N 9
%U http://geodesic.mathdoc.fr/item/PDMA_2016_9_a7/
%G ru
%F PDMA_2016_9_a7
A. A. Gorodilova. On differential equivalence of quadratic APN functions. Prikladnaya Diskretnaya Matematika. Supplement, no. 9 (2016), pp. 21-24. http://geodesic.mathdoc.fr/item/PDMA_2016_9_a7/