[Manuel_D]

Isn't encryption, by definition, obscuring the meaning of messages to everyone except authorized recipients?

I guess you could transmit the contents of messages in plain text but cryptographically sign the contents to authenticate. This would probably be useful to remotely administer infrastructure: e.g. have an "net operator only" mode for a repeater when pileups occur or somebody is not abiding by rules.

[BenjiWiebe]

You could transmit stuff encrypted with AES as long as you also transmitted your key (and scheme) in plaintext, afaik. So you could use ham radio to experiment with an encrypted scheme that you'd later use with non-ham bands/licenses.