In fact, 90% of the work in cracking RC4 is in this file here:-
https://github.com/stiabhan/p25lib/blob/master/src/adp/adp.cc https://github.com/stiabhan/p25lib/blob/master/src/adp/adp.cc
It's hardly a challenge these days. Perhaps we should add ADP key recovery into the OP25 GUI!
Cheers, Matt