I had a student when I was teaching crypto machine maintenance and repair at Lackland AFB in the early sixties. He had almost twenty years in, was married, and had children. He was cross training from food services, and was too smart to be cooking up SOS.
He took his class notes (they were also classified top secret) back to the barracks to study for a test, but was caught with them while entering the compound the next morning. He was a good student, and would have passed the test anyway.
He got twenty years at Leavenworth.