4 ms·

Pretty good illustration of how private and secure contact tracing can work here: https://ncase.me/contact-tracing/ https://ncase.me/contact-tracing/ Not sure

Pretty good illustration of how private and secure contact tracing can work here: https://ncase.me/contact-tracing/ https://ncase.me/contact-tracing/ Not sure whether that's what this implementation would look like.

harrygeez 7y ago
The problem with doing any sort of effective contact tracing requires special APIs for iOS and Android because newer versions of both OS disallow background communication and location gathering
- FabHK 7y ago
  You don’t need location gathering for this. All you do is store anonymous identifiers from people in the vicinity.
FartyMcFarter 7y ago
I'm not a security expert. However, this part looks worrying: > alice can also hide messages from times she wants to keep private If there's a need for this, doesn't that imply that the scheme does not actually keep Alice's privacy in all situations? Furthermore: > the random messages give the hospital NO INFO on where Alice was This seems to assume that the hospital (or anyone with access to the data, such as governments) didn't capture the broadcast messages together with their location. With enough Bluetooth receptors in busy areas, a government could easily find out where Alice had been by looking up each of her messages in their list of message/location pairs? Experts can probably come up with nastier and/or easier exploits...
- charlesju 7y ago
  This definitely isn't "private". It's just obfuscated.
  - LolWolf 7y ago
    Agreed, whenever you divulge any info, you're always losing bits of randomness (obviously, more or less depending on how good the protocol is!). In particular, given an adversary who has several points (receiving these codes) and knows the receiving location of each of these points can de-anonymize a person "A" who is COVID positive if they know, e.g., a minimal amount of A's usual daily movements (from cellphone tower location, for example). That being said, the government probably has better ways of knowing who has COVID-19 and other infectious diseases :)
qutw 7y ago
"The phone warns Bob to self-quarantine". So the app knows, and the crisis will indoctrinate people to trust such apps. Once the crisis is over, they'll continue to use such "safe" apps, for other purposes ...

harrygeez 7y ago

The problem with doing any sort of effective contact tracing requires special APIs for iOS and Android because newer versions of both OS disallow background communication and location gathering

FabHK 7y ago
You don’t need location gathering for this. All you do is store anonymous identifiers from people in the vicinity.

FartyMcFarter 7y ago

I'm not a security expert. However, this part looks worrying: > alice can also hide messages from times she wants to keep private If there's a need for this, doesn't that imply that the scheme does not actually keep Alice's privacy in all situations? Furthermore: > the random messages give the hospital NO INFO on where Alice was This seems to assume that the hospital (or anyone with access to the data, such as governments) didn't capture the broadcast messages together with their location. With enough Bluetooth receptors in busy areas, a government could easily find out where Alice had been by looking up each of her messages in their list of message/location pairs? Experts can probably come up with nastier and/or easier exploits...

charlesju 7y ago
This definitely isn't "private". It's just obfuscated.
- LolWolf 7y ago
  Agreed, whenever you divulge any info, you're always losing bits of randomness (obviously, more or less depending on how good the protocol is!). In particular, given an adversary who has several points (receiving these codes) and knows the receiving location of each of these points can de-anonymize a person "A" who is COVID positive if they know, e.g., a minimal amount of A's usual daily movements (from cellphone tower location, for example). That being said, the government probably has better ways of knowing who has COVID-19 and other infectious diseases :)

qutw 7y ago

"The phone warns Bob to self-quarantine". So the app knows, and the crisis will indoctrinate people to trust such apps. Once the crisis is over, they'll continue to use such "safe" apps, for other purposes ...