I have no experience with amateur radio, but from a quick google search, it looks like the relevent regulation is: (a) No amateur station shall transmit: ... (

I have no experience with amateur radio, but from a quick google search, it looks like the relevent regulation is: (a) No amateur station shall transmit: ... (4)...messages encoded for the purpose of obscuring their meaning, except as otherwise provided herein If you read through the rest of the restrictions, it looks like they are trying to setup a fairly specific environment on amateur radio, and encrypted traffic is inconsistent with that environment. http://www.hallikainen.com/FccRules/2013/97/113/index.php http://www.hallikainen.com/FccRules/2013/97/113/index.php