I have read that one of the British spook agencies secretly sponsored a newspaper cryptogram contest between the wars, and recruited the winners.
As for current recruitment -- when he was in high school, my son went to a two-week summer program for math and science geeks. Participants signed up for one of a half-dozen major courses, one of which was Principles of
Cryptanalysis. When I looked back over the program, I saw that the NSA was one of the sponsors. I have no doubt whatever that if you took that course and did well enough, you got a feeler afterward offering you a fat scholarship in exchange for a period of indentured servitude after graduation.
(My son took Chaos Theory instead.)