[sidewndr46]

Encryption is permitted for remote control of space borne systems.

Repeaters may use any method to limit access and control to authorized users.

[agiacalone]

I forgot about that one use case. But it's not allowed for most practical purposes in the U.S. at least.

[sidewndr46]

almost every single repeater I know of uses this method for remote control. I even remember listening to someone sending long strings of high speed DTMF, presumably to try and brute force control of the repeater. One of the managers said they weren't successful