I'm wondering how feasible it is for individuals to crack encrypted communication, and hack radios, preferably secured ones but I don't know where to buy one. T

I'm wondering how feasible it is for individuals to crack encrypted communication, and hack radios, preferably secured ones but I don't know where to buy one. Those encrypted radios in the 70s and 80s must be obsolete, right? I'm not into communicating with other people. Hacking computers and radios seem to be a lot more interesting.