For LAPP.... you quote...
Really! Was it a kind of barstool conversation perhaps. Because, you know "listening devices" need to be powered on to listen to "encrypted signals".
But do you realise how little power is required in the listening mode?
I have a radio locked clock that runs for a year on an AA battery. If I equipped it with a 35Ah battery it would keep receiving its time signal for maybe 100 years.
Also my Seiko watch lasts a year or more on just a miniature button cell.