  In this work, the field of a gravitational shockwave generated by a massless
point-like particle is calculated at the event horizon of a stationary
Kerr-Newman black hole. Using the geometric framework of generalized
Kerr-Schild deformations in combination with the spin-coefficient formalism of
Newman and Penrose, it is shown that the field equations of the theory, at the
event horizon of the black hole, can be reduced to a single linear ordinary
differential equation for the so-called profile function of the geometry. This
differential relation is solved exactly. Based on the results obtained, a
physical interpretation is given for the found shockwave spacetime, and it is
clarified how these results lead back to those of previous works on the
subject, which deal with the much simpler cases of gravitational shockwaves in
static black hole backgrounds.
