I've just read your lock and key whitepaper and have some questions.......

A discrete MCU with both Bluetooth and cellular chipsets and antennas is going to be far too big for mobile phones, MP3 players and many laptops, so we are presumably talking about larger household electronics - TVs, HiFi etc in this context?

If there is a need to use the cellular network, won't it be necessary for each device to have a contract/pay as you go deal with a mobile phone operator? A sim card will also be necessary?

If I lose the key, the device shuts down?

If I have a laptop with the MCU embedded I also need to remember to take the key when mobile? In this scenario, a TV that I leave at home would need it's own separate key?

On the subject of the key, how long will a charge last? Battery capacity is directly related to it's physical size.

I understand  that in the context of mobile phones you will be able to utilise the radio chipsets already built into the handset, but you will still have to carry the key or specify a when the next check is made and hope you are in the vicinity of the key at that time?