the safest way to reopen the economy
soon without causing a second wave in
the virus will involve some notion of
contact tracing but there's a common
misconception that this requires
tracking people's locations a friend of
mine nikki case recently brought up a
post explaining why contact tracing is
needed and importantly how the privacy
protecting variants of it work this was
done in collaboration with the
epidemiologist Parcells Holliday and the
security researcher carmalit Renko so
what follows is a video adaptation of
that post as far as kovat 19 cares there
are only three kinds of people not
infected yet infected and contagious but
with no symptoms and infected contagious
and showing symptoms if you have
widespread testing you can get people to
self isolate as soon as they show
symptoms the problem is that the virus
still spreads because of all the
contacts that happened while people are
contagious but asymptomatic
however if when someone shows symptoms
and tests positive you isolate not only
them but everyone they've been in
contact with you're staying one step
ahead of the virus the old-school way to
do this is with interviews but that's
slow it's inefficient and frankly it's
quite the intrusion on people's privacy
another approach in the modern world
would be to ask people who've tested
positive to forfeit all the geolocation
information from their phones and then
to track down the people who have been
in those same spots but now we are well
into bigbrother territory so do we have
to sacrifice privacy for health well
I'll just let Nikki's illustration speak
for itself here there are several clever
algorithms that let you alert everybody
who's recently been in contact with
someone who test positive for kovat
19:00 but without compromising the
privacy of anybody involved side note
here I found this very surprising I know
it shouldn't have been since I've gone
through this dance many times of
thinking something's impossible only to
see the cryptography makes it actually
possible but I would not blame anybody
at all for assuming that downloading an
app that can alert everybody you've been
in contact with must necessarily be
tracking and revealing your location and
a lot of other information the code for
these apps is entirely open so you don't
have to trust me
whoever wrote the app wernicki or anyone
to believe that it's doing what it
really claims to be doing anyway back to
the post let's see how this works with
the help of Alice and Bob Alice gets a
tracing app every five minutes
her phone sends out some uniquely pseudo
random gibberish to all the nearby
devices using Bluetooth because these
messages are pseudo-random they don't
use GPS and they contain no information
about Alice's identity not her location
not anything it really is gibberish but
the key point is that this gibberish is
unique now while her phone sends out
messages it also listens for messages
from nearby phones for example Bob's Bob
also has a privacy first tracing app
that's compatible with or the same as
Alice's if Alice and Bob stay close to
each other for more than five minutes
their phones will exchange respective
strings of unique gibberish both of
these phones remember all of the
messages that they said and heard over
the last 14 days again because the
random messages contain no information
Alice's privacy is protected from Bob
and vice versa
the next day alice develops a dry cough
and a fever Alice gets tested Alice has
kovat 19 this is not a good day for
Alice but she won't suffer in vain Alice
tells her app to upload all of the
random gibberish messages that it's been
sending out to a hospital database and
to do this she uses a one-time passcode
given to her by her doctor his code is
to prevent spam the database then stores
Alice's gibberish and again the random
messages give no information about Alice
where she was who she was with what she
was doing or even how many people Alice
met it really is meaningless to the
hospital but it's not meaningless to
Bob's phone Bob's phone often checks
this hospital list of random messages
that have come in from kovat 19 positive
cases essentially the hospital's
database is saying to all the phones out
there hey we just got this new random
gibberish if you've seen that same
random gibberish sometime in the last 14
days it means you've been in contact
with someone who just tested positive
for kovat 19
once Bob's phone recognizes some of
these numbers that are the gibberish
snippets now known to be associated with
positive test cases it can warn Bob to
self quarantine and so Bob cuts off the
chain of transmissions
we're staying one step ahead of the
virus and that's it that's how digital
contact tracing apps can proactively
prevent the spread of kovat 19 while
also protecting our rights
thanks Alison Bob stay safe
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one important thing to realize is that
you don't need everyone to have these
apps estimates have it that about 60%
would do the trick for covet 19 even if
you can't catch all possible contacts
what you need is to catch enough so that
the spread of coronavirus shifts from
growing exponentially to shrinking
exponentially for those of you who know
what this means what we need is for our
to drop below one the author of the post
that this video is an adaptation of is a
friend of mine nikki case who is a
brilliant programmer and artist he often
makes these interactive explanations of
societally important ideas including a
new one all about what happens next with
kovat 19 so I would highly recommend
taking a look at his work if you get the
chance he kindly made this post public
domain and moreover helped me in putting
together this video any reasonable plan
for reopening the economy without
causing a second wave in the virus will
include some kind of contact tracing and
given how counterintuitive the privacy
protection here can be I wanted to do
all that I could to help amplify this
message if you agree please do share
either Nikki's original post or this
video adaptation of it and since the
time that Nikki posted that Apple and
Google have put out press releases about
their own interoperable contact tracing
systems and I'll tell you I'm one of
those people who aggressively turns off
location tracking as much as I can on my
phone no matter how annoying the apps
can be about asking I'm looking at you
Fitbit but I am 100% onboard with these
apps because it's not tracking your
location or anything like that and if
you're a nerd like me who wants to dig
into the cryptography a bit I would
recommend looking at the white paper and
the code for the BP 3t algorithm for
which I've left links in the description
and as a final note among the many
unfortunate consequences of the lock
downs is a spike in calls to mental
health services like the suicide
prevention hotline if somebody that you
know is at risk of suicide give them a
call make sure they're doing okay and if
you're at risk take a look at the
resources in the description and if it's
an option reach out to the people in
your life to talk about what you're
going through
you
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you
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