4 ms·
In a sense urban area, that would help. In small towns, or out in the country? Not a chance.
by LyndsySimon 7y ago
In a sense urban area, that would help. In small towns, or out in the country? Not a chance.
- c22 7y agoWhy not? To correlate any meaningful data an attacker would have to reverse a significant portion of the database. The most serious attack I see would be a brute force over time of Bob's location segment. At most this gives Eve retroactive information about when Bob was home after Bob has tested positive and uploaded his data. It still doesn't give any insight into where Bob went when he left except perhaps in extremely sparse areas. Our imaginary service can help reduce the impact of this attack further by rate limiting requests and discarding old data as soon as it's no longer relevant. This failure mode is probably still less intrusive than the current system of asking people in quarantine to detail all of their recent movements. Ironically, you might achieve better anonymity by making the time and space boundaries smaller, but at the expense of more false negatives when checking for exposure.