We’ve known for years that things like webcams and microphones can be used to spy on us and steal our passwords. Now that cool wearable device on your wrist can give attackers your PIN. Basically the movements of your hand can be recorded by the device and sent to an attacker for analysis. Looks like that have an 80% chance of getting it on the first try. From a technical point of view it’s a cool hack. From a security point of view it’s another reason to be cautious about wearing a computer all the time.