Sur la non-linéarité des fonctions booléennes

François Rodier (1)

1 IML - Institut de mathématiques de Luminy

Boolean functions on the space $F_{2}^m$ are not only important in the theory of error-correcting codes, but also in cryptography, wherethey occur in private key systems. In these two cases, the nonlinearity ofthese function is a main concept. In this article, I show that the spectral amplitude of booleanfunctions, which is linked to their nonlinearity, is of theorder of $2^{m/2}\sqrt{m}$ in mean, whereas its range is bounded by$2^{m/2}$ and$2^m$.Moreover I examine a conjecture of Patterson and Wiedemann saying that theminimum of this spectral amplitude is as close as desired to $2^{m/2}$.I also study a weaker conjecture about the moments of order 4 of theirFourier transform. This article is inspired by works of Salem, Zygmund,Kahane and others about the related problem of real polynomials withrandom coefficients.

Mots clés: rayon de recouvrement; code correcteur d'erreur; cryptographie; non-linéarité; fonction booléenne; polynôme aléatoire; transformation de Fourier.; transformation de Fourier

Domaines: Théorie des nombres [math.NT]

François Rodier. Sur la non-linéarité des fonctions booléennes. 2003. ⟨hal-00000454⟩