3 ms·

In widely distributed and important spec like this it may be useful to look for what is conspicuously absent or unstated, rather than simply reading the precise

by jka 7y ago

In widely distributed and important spec like this it may be useful to look for what is conspicuously absent or unstated, rather than simply reading the precise positive language. To my mind this phrase under 'Privacy Considerations' in the Cryptography Specification stands out: "A server operator implementing this protocol does not learn who users have been in proximity with or users’ location unless it also has the unlikely capability to scan advertisements from users who recently reported Diagnosis Keys." That phrase explicitly mentions that server operators cannot learn about user proximities. What I reckon may be unstated there is that it could be possible for adversaries with sidechannel / network monitoring capability to learn those kind of details about users (i.e. internet, cell data, and other data network operators). If such a side door did exist, it would seem in the public interest to be aware of the scope of the availability of that data, especially given the potential (physical, social) vulnerability and risk of those users. I'd also like to be proven wrong about the possibility of such sidechannel attacks by anyone who understands the spec in more detail. [1] - https://covid19-static.cdn-apple.com/applications/covid19/current/static/contact-tracing/pdf/ContactTracing-CryptographySpecification.pdf https://covid19-static.cdn-apple.com/applications/covid19/cu...

ericlavigne 7y ago
The approach outlined by Apple and Google is very similar to, and likely based on, the TCN protocol developed by a coalition of open source projects. If you'd like to discuss possible vulnerabilities and propose further improvements, there's an active community already doing that who would be happy to have one more contributor. :-) https://tcn-coalition.org/ https://tcn-coalition.org/
- jka 7y ago
  Thank you, I'll take a look into TCN and the protocol. Do you know whether TCN have worked with and/or compared notes with OpenTrace[1]? [1] - https://github.com/OpenTrace-Community https://github.com/OpenTrace-Community
  - tastroder 7y ago
    The projects I've seen inside of TCN seem aware of OpenTrace and the code / data they put out over the last few days, not sure if direct contacts exist yet.
  - ericlavigne 7y ago
    I’m part of the CoEpi project, one of the member projects of the TCN Coalition. I see that some of my teammates are searching through the OpenTrace code to see if anything there is worth taking, such as their device-specific bluetooth range calibrations. I don’t think there’s been any two-way communication between these teams.

by jka 7y ago

ericlavigne 7y ago

The approach outlined by Apple and Google is very similar to, and likely based on, the TCN protocol developed by a coalition of open source projects. If you'd like to discuss possible vulnerabilities and propose further improvements, there's an active community already doing that who would be happy to have one more contributor. :-) https://tcn-coalition.org/ https://tcn-coalition.org/

jka 7y ago
Thank you, I'll take a look into TCN and the protocol. Do you know whether TCN have worked with and/or compared notes with OpenTrace[1]? [1] - https://github.com/OpenTrace-Community https://github.com/OpenTrace-Community
- tastroder 7y ago
  The projects I've seen inside of TCN seem aware of OpenTrace and the code / data they put out over the last few days, not sure if direct contacts exist yet.
- ericlavigne 7y ago
  I’m part of the CoEpi project, one of the member projects of the TCN Coalition. I see that some of my teammates are searching through the OpenTrace code to see if anything there is worth taking, such as their device-specific bluetooth range calibrations. I don’t think there’s been any two-way communication between these teams.