10 ms·
GP is correct, but it doesn’t matter much. They were referring to daily key, not the EphID (RPI in the Apple/google spec). DP3T specifies that SK _t = H( SK _{
by FabHK 7y ago
GP is correct, but it doesn’t matter much. They were referring to daily key, not the EphID (RPI in the Apple/google spec).
DP3T specifies that SK _t = H( SK _{t-1} ). In that design, you share the daily key from when you started to become infectious, and then the subsequent ones can be computed. Then you go into quarantine, stop being infectious, and (see spec) create a new random daily key going forward (or delete the app).
In the A/G proposal, daily keys can’t be correlated, and you share the daily key for each day you were infectious.
The end result seems pretty much the same for me.
- sratner 7y agoThe difference is that you can continue tracking a person indefinitely, even after they are no longer infectious. It requires explicit user action to avoid that (opt-out vs opt-in).
- FabHK 7y agoIf the DP3T app is implemented to spec and creates a new random daily key after the infectious period ends, no. If the A/G app is not implemented to spec and keeps uploading daily keys even after the infectious period is over, yes. So, dunno. A/G has a bit more privacy (maybe) for 5x more data volume than DP3T.