Seems to me like the overhead it would add would way outweigh the benefit for the use case. I wouldn't want to wait an extra 10 seconds for the audio to finish transmitting every time just to prevent nonexistent spies in my kitchen from listening in.
The data/time overhead would be negligible. Engineering overhead to implement it on the other hand, perhaps not.
> The data/time overhead would be negligible.
Doubling or tripling the amount of data sent would be negligible over a wire, but an audio protocol won't be as snappy. Then there's the matter of trust/decryption. How are those keys being kept safe? What happens if I lose access?
You can encrypt data and keep the exact same original byte size.
If you're using symmetric encryption, sure. And then every dishwasher has the same symmetric key, guaranteeing it'll leak.
Everything uses symmetric encryption, including asymmetric encryption. Using symmetric encryption doesn't mean you'd use the same key for every dishwasher, you'd obviously just pair the devices and generate a new key, like everything does nowadays. Also, my dishwasher doesn't use any sort of encryption, and it still leaks.