This system goes to quite some lengths to preserve privacy.
If you are going to attack it, you need to actually address what it does and explain why you don't think that is sufficient.
If you are going to attack it, you need to actually address what it does and explain why you don't think that is sufficient.
A tech-savvy person could drive by your house and find out your IDs for that day. If you reveal them later on (as you would if infected), that person would know you're infected. In small towns a single person could in practice publish a database of all infected households.
A government can install Bluetooth receivers throughout a city and find out where an infected user passed by.
Or if you don't want to, a tl;dr is:
1. Your phone broadcasts a message via BLE every X milliseconds with a "random" ID. The ID is only predictable with a secret key which never leaves user device before "voluntarily revealing" (I agree this can be shaddy). The "random" ID is rotated every Y minutes.
2. The secret key will be rotated daily. The user device only reveals last 14 keys if user voluntarily do so.
3. Note that every BLE advertisement already contains a hardware address and your phone does this regularly. Guess how they mitigate this privacy issue? Rotating the hardware address every Y minutes. So no additional entropy being leaked here, unless you have the user's secret key.
A government can do much more with less effort using other means. And it's hard to see the value of making that kind of attack as an individual.
If this system goes to some lengths to preserve privacy, slippery slope argument doesn't really apply.
There is not NEED to use this scheme in such a convoluted way. There are far better ways to spy, and the way to protect against it is through politics and laws.
You really think that won't be the predicate for abandoning security and anonymity?
edit: and no, the observable "ID" is not fixed, so you can't link two unknown IDs.