Tinkerer. (For probably 90% of situations it can be explained that simply)
"Tinkerers reversed engineered the new government X" "Tinkerers were able to crack the new Purple-ray disc standard"
I think it sounds nicer to say "hacker" than "tinkerer," but again, 90% of the time you can just replace one with the other if you need a quick way to explain it to someone.