41 lines
2.2 KiB
Markdown
41 lines
2.2 KiB
Markdown
# Original NHSx app vs Post-may Apple/Google API-based app
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* NHSx app builds a database of significant contacts (<2 metres for at least 15 mins) who can be alerted if the user reports symptoms (presumably a positive test, too) (from [independent](https://www.independent.co.uk/news/uk/home-news/coronavirus-app-nhs-contact-tracing-cyber-attack-hack-a9500401.html))
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* Users could be notified of false positive if this was found out later
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* NHSx uses a centralised model (FIXME: Find decent source and explanation!)
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* A centralised server figures out the matching process
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* Phone has a unique key thats sent to other devices that come in contact
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* If the user logs positive, device tells server their key is positive
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* Other device asks NHS server if any device keys it's received are positive (**here, the server checks for matches**)
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* If the key is found to have logged positive, the user is alerted
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* The server knowing if your key has come into contact with someone could pose a risk of tracking by gov/hackers
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* Could make tracking outbreaks on a national scale easier
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* App connected to NHS account
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* Battery-saving features on phones (especially iPhones) could pose a challenge to keeping the service running 24/7 on the device
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* Even if not, Apple claimed NHSx solution would be less power-efficient
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* Apple/Google uses a semi-decentralized model (good ass diagram [here](https://www.bbc.co.uk/news/technology-52263244))
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* Uses BLE to reduce power usage
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* No NHS account, name or details need to be given
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* When two phones meet, a unique key is created and exhanged between them
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* When one logs a positive, the user agrees to upload the key to a central database
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* All other phones regularly download the central database, and then check (**matches are searched for on-device**) for any keys they have received from other devices
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* If the key is in the db, the user is alerted, but the central server does not know about the match.
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### Similar between the two
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* Risk of high false-positives/Self-certification being used maliciously
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* This was more of a concern when the apps were in development, as conveninent testing (LFD) was not easily available so self-cert was the most likely way to log "positive" on the app
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