the contact-tracing scheme they are offering to health authorities and brought
forward its launch.
intend to release a software building block to developers on Tuesday, allowing
them to build compatible apps. A fortnight ago, the firms said it would take
until mid-May. Apple’s version will require an updated version of its mobile
operating system. Some countries, however, would prefer the firms to be less
have confirmed they are pursuing designs of their own, and are pressing Apple
to let them have greater access to the iPhone’s capabilities without having to
adopt the initiative.
wing of the NHS, confirmed it was “working with Apple and Google” on
its UK contact tracing app, but stopped short of committing itself to the companies’
apps are based on the principle that people’s smartphones can be used to log
when two people are in close enough proximity for long enough that there’s a
high risk of contagion if one of them has the coronavirus.
one of the phone-owners is subsequently diagnosed as having caught the virus,
others they might have infected can be sent alerts advising them to get tested
or go into self-isolation.
combining the use of such apps with other measures – including manual contact
tracing by humans and frequent handwashing – the hope is that the spread of the
disease can be slowed or suppressed.
system is based on the use of Bluetooth Low Energy (LE) beacons. Effectively,
the two handsets wirelessly “shake hands” with each other, and in
doing so exchange a string of randomly-generated numbers that can be used to
log matches without revealing the users’ names, location or other identifying
the team responsible said they had listened to feedback received from health
authorities, governments and data protection watchdogs, and made changes to
both increase security and to make it easier for apps to be built using the API
(application programming interface) building block they are providing.
about different devices’ Bluetooth power levels, to help developers better
estimate how far two handsets are from each other.
decide for themselves how close together phones should be and for how long to
trigger a handshake.
from logging any meeting as having lasted longer than 30 minutes.
the transmission power of the phones, to prevent anyone retrospectively using
the logs to reveal what models had been involved.
different encryption algorithm – AES – to reduce the toll on battery life.
users to install a new version of iOS 13 to use the API. That means any handset
older than the iPhone 6S – which was released in September 2015 – will be
running version 6 of Google’s operating system, which launched in October 2015,
or higher will work without needing an update.
system has been described as “decentralised” as the contact-matching
takes place on the users’ devices, preventing the authorities being able to see
who got an alert unless a user decides to disclose the fact – for example to
request a diagnostic test.
are pursuing “centralised” designs. This would give them more insight
into the number of alerts being sent out and potentially the ability to
re-identify users, meaning they would not truly be anonymous
nations face a problem with the iPhone versions of their software. Apple places
restrictions on third-party apps’ use of Bluetooth, which it is only dropping
if the authorities adopt its scheme.
heavily restricted on iOS when the app is in the background,” explained
Quentin Zervaas, a developer who is building a Google-Apple compliant app.
to occasionally broadcast or receive data while backgrounded, but there are no
guarantees how frequently this would be, and the app would be competing against
any other apps on your phone trying to use Bluetooth.
tracing it can’t constantly send or receive the necessary data necessary to
effectively keep track of every device you come into contact with.
all the contact tracing apps should be using the system level tools Apple and
Google are rolling out.”
declined to discuss the implications of countries that opt to go it alone.