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corona-warn-app / cwa-wishlist

Central repository to collect community feature requests and improvements. The CWA development ends on May 31, 2023. You still can warn other users until April 30, 2023. More information:
https://coronawarn.app/en/faq/#ramp_down
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verifiability by the Health Department (Gesundheitsamt) for quarantine etc. #510

Open kolAflash opened 3 years ago

kolAflash commented 3 years ago

If you had an infection contact - either by Check-In or exposure notification - it would be helpful if you can (voluntarily) proof this to the Health Department (Gesundheitsamt).

If the Health Department is able to verify, that you didn't fake an infection contact, this would help them to support you staying in quarantine / isolation.
Mostly important the Health Department could allow you not to go to work and stay at home.
But because some people may not like to go to work at all ;-) this should be somehow verifiable.

 

Technical

I'm not sure if this is cryptographically possible for the standard Exposure Notification system. But for the Check-In system I'm having two different ideas.

 

Hash Upload

  1. When installing CWA you'd be asked to (voluntarily) register an account with your name at a server trustful to the Health Department.
    Your name is needed to detect multiple registrations, so one can't just create hundreds of accounts registering at all possible locations to fake an infection contact.
  2. When you check in, your phone will hash the Check-In location with a random seed.
    Your phone will store the seed locally and ask you to (voluntarily) upload the hash to the server. The server will store the hash and the time when it's been uploaded under your account. This won't allow the Health Department to get any concrete information, because they can't get any information from the hash. The Health Department will only know that you checked in somewhere, but won't know where. Also there will be an limit on how many hashes you can upload in a certain time interval to prevent infinite fake-Check-Ins to fake an infection contact.
  3. If your CWA informs you about an infection at the location where you've checked in, you'll have the choice to provide the seed + location where you Checked-In and met an infected person.
    If you provide this data to the Health Department, they'll be able to verify that they really got the hash before. So you won't be able to make up a Check-In after the infection event was made available publicly.

 

Signing by the location

Another approach would be to make the locations host sign your Check-In. This could be done without sending anything over the Internet. But the locations host would need a device that can actively receive data from your device (e.g. via Bluetooth) and return a cryptographic signature, that you've really checked in at that location.

Ein-Tim commented 3 years ago

FYI: The UK tried something like this with their app ("NHS Covid-19") and Apple/Google blocked this update from the store: https://www.bbc.com/news/technology-56713017

So seems like they are not allowing this, even not voluntary.

heinezen commented 3 years ago

Hey @kolAflash

A few things to note about your feature request:

  1. The app itself cannot detect if you are infected, it can only detect if you were exposed to an infected person. Only a PCR-Test or rapid test (Schnelltest) can prove that you are infected. It also can't prove that you are not infected since using the CWA is voluntary. A proof of exposure not as useful to the health department as a proof of infection.
  2. The CWA will get a "proof of infection" in the next release (CWA 2.2) which should arrive this week. It allows you to link personal information to a rapid test (Schnelltest) result. This feature should implement everything you proposed, but without revealing the visited locations. It would also require you to make a rapid test, but that is necessary for the proof of infection.

Let me know if you need more details or if I misunderstood something in your post.

Corona-Warn-App Open Source Team

Ein-Tim commented 3 years ago

@heinezen Could you point out the issue that this issue duplicated? Thank you!

kolAflash commented 3 years ago

@heinezen

 

  1. The app itself cannot detect if you are infected, it can only detect if you were exposed to an infected person.

I know.
That's what I meant by "had an infection contact ".
In other words: The app can tell if you had contact (were exposed) to an infected person.

 

A proof of exposure not as useful to the health department as a proof of infection.

The value of a verifyable "proof of exposure" depends on the situation. If you've just been informed by CWA that you had a high risk contact yesterday, there's no time to loose to get the Health Department permission not to go to work and stay at home.

A "proof of infection" by PCR test just takes too long. (usually more than 12 hours)
And a rapid test won't help either in this situation, because it can't detect the infection in the first days. But you're already infectious in the first days.

 

  1. The CWA will get a "proof of infection" [...]

See above.
(as said, I'm not talking about a "proof of infection" but about a verifiable "proof of exposure")

Based on this, please remove the duplicate flag.

 

 

@Ein-Tim

FYI: The UK tried something like this with their app ("NHS Covid-19") and Apple/Google blocked this update from the store: https://www.bbc.com/news/technology-56713017

So seems like they are not allowing this, even not voluntary.

Google allows the voluntary "Data donation" (Datenspende). So I guess the proposed feature might be OK for Google two.