Bitcoin Universe · Model 08
Anatomy of a signing device
A hardware wallet keeps the key away from your computer and shows you, on its own screen, exactly what it is about to sign. Walk through one payment, then try it with an infected computer.
Build the payment
The key storage boundary, data going to the device, the buttons when they can sign
The signature coming back
Fictional device, demonstration keys
The device is invented; real products differ in chips, screens, connections and how strongly they resist physical attacks. Keys come from public test phrases and the signature is a real ECDSA signature over a stand-in message. The address-swap attack shown here is real and is why the full address must be checked on the device screen against the address your recipient sent you.