But: your data will get on a central server, when you or someone else designates positive.
There will be data exchange all over Europe.
The bluetooth hash is not anonymous, because contacts shall be "warned". It's clear by functionality and openly said, it's "pseudonymous".
Of course you can relate a contact out of a list with a device.
Nothing else than with google API.
Right here, Google is out, gov is still in.
About Germany: existing data will get abused and there is no barrier which prevents that data from being shared, once they are on the server.
ok, how the system is implemented simplified:
1. ~ every 15min phone generates random number
2. phone sends out hash of random number via BLE
3. you test positive and submit your random numbers of the last 2w
and in paralel:
0. always save all hashes you receive via BLE on your phone
1. ~once a day request all new submitted random numbers
2. check if hashes of downloaded random numbers match the once received via BLE
3. If not show no contacts, if yes show alarm.
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