  It is known that crooked functions can be used to construct many interesting
combinatorial objects, and a quadratic function is crooked if and only if it is
almost perfect nonlinear (APN). In this paper, we introduce two infinite
classes of quadratic crooked multinomials on fields of order $2^{2m}$. One
class of APN functions constructed in [7] is a particular case of the one we
construct in Theorem 1. Moreover, we prove that the two classes of crooked
functions constructed in this paper are EA inequivalent to power functions and
conjecture that CCZ inequivalence between them also holds.
