Automorphism groups of power functions

Abstract Let 𝐹 be a finite field, and for any integer k ≥ 0 k\geq 0 , let p k p_{k} be the power function on 𝐹 defined by p k ⁢ ( x ) = x k p_{k}(x)=x^{k} . We determine the group of CCZ automorphisms of p k p_{k} , i.e. the group of invertible affine transformations which preserve the graph of p k p_{k} .