  In a prior paper [14], along with P. Ellingsen, P. Felke and A. Tkachenko, we
defined a new (output) multiplicative differential, and the corresponding
c-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 show that their c-differential uniformity
increases significantly, in some cases.
