If they've said "please don't encrypt", they're making a much broader request than is necessary to comply. The only thing we really need is for a protocol to h

If they've said "please don't encrypt", they're making a much broader request than is necessary to comply. The only thing we really need is for a protocol to have some way for us to transmit a callsign in cleartext (otherwise there would have to be a break in data exchange every ~10 minutes for transmission of a callsign unencrypted). On WiFi this gets accomplished by setting the SSID to our callsign. The actual data could be encrypted, but we would have to record (and arguably publish) any keys (including session keys) used in the process.