32 ms·
Some of the attacks seem to be high cost, low payoff. Have you read the newer version? There is a new proposal that would protect against most of these attack
by xorfish 7y ago
Some of the attacks seem to be high cost, low payoff.
Have you read the newer version?
There is a new proposal that would protect against most of these attacks.
- john_payette 7y agoDP-3T admits now that the best solution is the Apple-Google one. They greatly contributed to the design of the A-G solution so kudos to them. After reviewing this critical review of DP-3T, the only attack I see that applies to the Google-Apple solution is the replay attack. It can be fixed easily by the solution proposed by Prof. Serge Vaudenay of EPFL in Section 4.4 of https://eprint.iacr.org/2020/399.pdf https://eprint.iacr.org/2020/399.pdf. In a nutshell, send a tag along the ephemeral ID. This tag would be a message authentication code (MAC) computed with the ephemeral ID and a coarse timestamp of when it was sent using the sender's key, SKt. When Apple-Google sends out the SKt keys of the infected people to everybody, recipients will go through the ephemeral IDs they saw to look for matches. When there's a match, the tag will also be checked, i.e. does the tag I compute based on the timestamp when I received the ephemeral ID match the tag I received. If yes, then it was sent by this infected person. Otherwise, it's a replay attack and should be discarded.