Apple, Android, Google, and now Microsoft have a feature called "auto|smart|dynamic|proximity lock" which enables to unlock your computer by simply carrying a (Bluetooth) support device with you. That means if you move "too far" away from your computer it will automatically lock your screen, contrary if you move to your device to the computer it will automatically unlock.
I am interested in researching the security aspect of these methods, e.g. what are the specifications and how are they actually implemented. However, I am surprised (well, in the case of Apple not so much) that details of their smart locks are not widely available, not to say not publicly available at all.
In the case of Apple, I was already able to find some specifications that the protocol uses both, Bluetooth LE and WiFi. But do they prevent re(p)lay attacks? Can malware installed on the smartphone give an attacker the power to unlock the computer?
My question is: Where do I start? Do you know any sources that give me pieces of information about how the locks work? I think it would be not feasible to sniff the send traffic (which would be extremely annoying in the case of Bluetooth frequency hopping), so how else could I get information about what is sent over the channel?