Investigations on c-(Almost) Perfect Nonlinear Functions

In a prior paper (Ellingsen <italic>et al.</italic>, 2020), two of us, along with P. Ellingsen, P. Felke, and A. Tkachenko, defined a new (output) multiplicative differential and the corresponding <inline-formula> <tex-math notation="LaTeX">$c$ </tex-math></inline-formula>-differential uniformity, which has the potential of extending differential cryptanalysis. Here, we continue the work by looking at some APN functions through the mentioned concept and showing that their <inline-formula> <tex-math notation="LaTeX">$c$ </tex-math></inline-formula>-differential uniformity increases significantly in some cases.