Let f(x) be a mapping f: GF(p ⁿ ) →GF(p ⁿ ), where p is prime and GF(p ⁿ ) is the finite field with p ⁿ elements. A mapping f is called differentially k-uniform if k is the maximum number of solutions x ∈ GF(p ⁿ ) of f(x + a) − f(x) = b, where a, b ∈ GF(p ⁿ ) and a ≠ 0. A 1-uniform mapping is called perfect nonlinear (PN). In this paper, we propose an approach for assurance of perfect nonlinearity which involves simply checking a trace condition.