> A watermark is a visible mark embedded in a physical or digital medium to verify authenticity or assert ownership.
We also recently had this with LG spy-TVs. Cars here in the EU also spy on people, allegedly to show how alert they are. Perhaps they sneakily upload that information somewhere ... Facebook also has the spy-glasses now. People getting angry about Flock-spy-cameras.
It seems we are now in the age of spying of everyone at all times. Future spying will be done via even smaller devices.
People are most afraid of cameras, somehow.
The concern is valid, but microphones are far worse. They're simpler, smaller, extremely sensitive to sound and an order of magnitude cheaper, both the mic itself as well as any spying with it.
It is possible to record voice using few bytes, to send later. It's further possible to transcribe cheaply into text, and analyze said text.
And mics are already everywhere, including in devices that do not need them, as well as speakers that can be rewired by software to act as microphones.