I had a relative that once worked in "government security" for the U.S. government. What that meant, we weren't permitted to know. Personally, I think he was full of crap and here's why: in his Professional Opinion, any encryption algorithm implemented in software was doomed to failure because "it could be hacked" - he was completely unaware that any hardware circuit can be emulated in software.

Point: it tends to be these very gov't lackeys that think just because the signal is in the air that it can be intercepted, decoded, decrypted and its plaintext content recorded.