AndreasGassmann
Crypto Design for the project
Currently the crypto machinery for the project is involved the following workflow:
- The creation of the random IDs
- Broadcasting them using BLE between mobiles in the range of BLE
- Polling the random IDs of infected users on the mobile phones
- Matching receiving IDs with local IDs
The threat model of the app can be seen as follows:
- External mobile users not in the range of mobile users using the app should not receive anything
- Mobile users in the range of user using the app are seeing only random IDs without being able to track anyone
- Third parties as the relay server do not learn any identifiable information.
Proposal (WIP)
Random IDs
Model H as a hash function and r a random nonce. Time is split in time slots t_1,t_2,...,t_i.
Init Phase:
The app picks a random nonce r, which never leaves the device and it is used to create random looking beacons b_i for each location
-
H(r) = S -
K_0 =random key
Broadcast Phase
- K_i = H(K_i-1)
- H(K_i-1,t_i) = b_i
Hi @leontiad thank you for this feedback, can you please check and review the proposal we have here and tell me what you think: https://github.com/AndreasGassmann/WeTrace/wiki
Hi @dcale it is not clear why you want to use public key encryption here. The above design overviews just sends pseudorandom ids, which are untraceable . It would be better to put your wiki doc to an issue in order to open discuss it