COMSEC, an acronym for
Communication Security, includes
military hardware and
software. To handle
IFF,
UHF and
VHF, you had to have a
Secret clearance (all are short range). Theoretically, the
HF codes were classified
Top Secret on ships, but for those of us who handled the codes for
helicopters, it was only Secret. This always resulted in a big to-do between the
air detachment and the
Radio Room folks.
Not too well known is that some codes were put in fast-key guns so that a technician could totally re-code a helicopter in a few minutes at the end of the code-life day. These guns ranged from pins that pushed into the COMSEC gear, thereby acting like a short-term 50 to 100 tumbler lock, to electronic keying guns that transferred over a regular cable (which was also classified, even though it was a silly wire).
The actual codes themselves would be entered into the guns, then the papers destroyed at the end of the code-life day, depending on the rules at the time. Some dissolved in water, some were burned. COMSEC always required two-man integrity, where two folks with clearance would keep the gear in their possession until it was secured in a safe that had two locks.