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ROBERT-proximity-tracing / documents

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Background limitation and impact? #33

Open LegFranck opened 4 years ago

LegFranck commented 4 years ago

TraceTogether/Bluetrace highlight in their WP the major limitation of BLE not being able to run in the background on iPhones (when screen off) requiring users to keep their phone's screen on by all times (see excerpt below). It seems that the background restrictions have not been considered in your design since you focus on privacy. Nonetheless:

  1. Did you evaluate what is the impact of this limitation on contact discovery and hence contact tracing?
  2. How do you plan going around that other than having to use the Apple-Google framework? WP-Bluetrace I've highlighted this limitation in my post here: https://medium.com/@legfranck/the-good-and-the-bad-of-apple-googles-privacy-preserving-contact-tracing-744806450be9
Julien-Roger commented 4 years ago

Other issue on both iOS and Android is that system might kill app anytime if it needs to free some resources. When app is not running (not even in background), collecting bluetooth information is not possible.

PRIVATICS-Inria commented 4 years ago

The iOS issue with applications in background being unable to send/receive BLE traffic is a key practical issue. There are technics to mitigate it and this is what will be deployed in GB. However this is not our goal in the ROBERT protocol design team to focus on this topic.

LegFranck commented 4 years ago

To mitigate the background issues, you can have post-processing on the backend to uncover contacts that where not reported because of those background limitations. Let's say Alice, Bob and Dave are close-by but only Alice has her screen open. Alice will discover both Bob and Dave. With transitivity you can conclude that Bob and Dave were also close-by. Issue is going to be estimating the distances in this setup.

On Thu, 30 Apr 2020 at 15:05, PRIVATICS Inria notifications@github.com wrote:

The iOS issue with applications in background being unable to send/receive BLE traffic is a key practical issue. There are technics to mitigate it and this is what will be deployed in GB https://www.bbc.com/news/technology-52441428. However this is not our goal in the ROBERT protocol design team to focus on this topic.

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Julien-Roger commented 4 years ago

Why Alice would have her Covid application open? This application is not a social network app or an internet browser on which the user might spend some time reading content, watching pictures, videos.

This application will be almost NEVER in foreground state.

LegFranck commented 4 years ago

@Julien-Roger I don't get your comment. Whom are you answering to?