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<article> | |||
<h1>Temporary Contact Number based Contact Tracing</h1> | |||
<h2><a href="https://lucumr.pocoo.org/2020/4/9/tcn-contact-tracing/">Source originale du contenu</a></h2> | |||
<p class="date">written on Thursday, April 9, 2020 | |||
</p> | |||
<p>I have already talked here before about <a class="reference external" href="https://lucumr.pocoo.org/2020/4/3/contact-tracing/">privacy preserving contact | |||
tracing</a> to fight Covid-19 but I figured I | |||
give an update to this. I have spent the last week now investigating | |||
different approaches to this and my view has changed quite a bit.</p> | |||
<p>I strongly believe that contact tracing through phone apps is one of our | |||
best chances to return to normal and without losing our civil liberties. | |||
If you want to understand why, have a look at <a class="reference external" href="https://lucumr.pocoo.org/2020/4/3/contact-tracing/">previous post about this | |||
topic</a>.</p> | |||
<div class="section" id="two-fundamental-approaches"> | |||
<h2>Two Fundamental Approaches</h2> | |||
<p>In the previous post I talked in favour of a partially centralized | |||
approach. This was largely because I felt that one of the inherent | |||
problems of any privacy preserving contact tracing system could be | |||
somewhat mitigated. That downside is that a person could always use any | |||
such contact tracing system in a way where they could determine that | |||
another person they met tested positive for covid-19 later. With a | |||
system that has support from a central authority this still cannot be | |||
prevented, but such behavior could be detected as abusive. However I am | |||
not quite convinced that this would just be security by obscurity and that | |||
the more correct way to deal with this is to just fundamentally | |||
communicate to users that this is an inherent property of the system.</p> | |||
<p>So the disclaimer to any app has to be: if you do not want that other | |||
people discover when you will test positive for covid-19 you should not | |||
use any contact tracing apps. Which is also why I strongly believe that | |||
any such system absolutely needs to be voluntary.</p> | |||
<p>So if I no longer believe in favour of the centralized approach, what do I | |||
prefer then? Quite simply put an approach based on temporary contact | |||
numbers, short <a class="reference external" href="https://tcn-coalition.org/">TCNs</a>. These protocols are | |||
fundamentally decentralized and give us some other benefits.</p> | |||
</div> | |||
<div class="section" id="reality-on-the-ground"> | |||
<h2>Reality on the Ground</h2> | |||
<p>What makes application based contact tracing very interesting is that they | |||
take advantage of working on top of a widely deployed piece of hardware: | |||
smart phones. Specifically smartphones which support Bluetooth low | |||
energy (BLE). If you hold an AirPods case close to your iPhone you will | |||
notice that something happens on your screen. BLE is what enables that.</p> | |||
<p>The downside of this is that BLE comes with some restrictions. The two | |||
most relevant ones are the payload size. BLE comes with different modes | |||
and different platforms call this in different ways but the most | |||
compatible and energy preserving modes restrict us to under 30 bytes of | |||
payload. That's not enough to make fancy public key cryptography work | |||
which would be necessary for centralized approaches to play to their | |||
advantages. This is also why systems that currently follow the | |||
centralized approach will typically exchange a short ID and the extra | |||
payload is then actually exchanged through the cloud or <a class="reference external" href="https://en.wikipedia.org/wiki/Bluetooth_Low_Energy#GATT_operations">GATT</a>. | |||
The former makes a system that could be somewhat decentralized much more | |||
centralized.</p> | |||
<p>TCN based protocols instead will exchange just random identifiers instead. | |||
Most TCN based protocols currently suggest between 16 and 26 bytes of | |||
effectively random data which is easier to work with.</p> | |||
<p>Another complexity is that at present iOS devices in background cannot | |||
discover each other. This limitation might be solvable by Apple and it | |||
appears various groups are currently in contact with Apple to see what can | |||
be done. Interestingly an iOS device with the app in background can be | |||
discovered by an Android device so there might be a way to fix this.</p> | |||
</div> | |||
<div class="section" id="tcn-strawman-protocol"> | |||
<h2>TCN Strawman Protocol</h2> | |||
<p>The TCN strawman protocol is the most basic of all these protocols. It | |||
was first written down by the <a class="reference external" href="https://www.coepi.org/">Co-Epi project</a> | |||
and is very easy to explain.</p> | |||
<ol class="arabic simple"> | |||
<li>all mobile phones randomly generate TCNs and remember and broadcast | |||
these.</li> | |||
<li>all mobile phones check against a server which publishes TCNs that are | |||
known to be covid-19 positive.</li> | |||
<li>all mobile phones check their local contact list against the downloaded | |||
list locally for an intersection.</li> | |||
</ol> | |||
<p>Step 2 is the only one where a central system is necessary. For instance | |||
this could be the server of the Austrian Red Cross which publishes TCNs. | |||
Since the TCNs of encounters are only stored on the devices they have to | |||
get on contact with covid-19 tested positive individuals first.</p> | |||
<p>The strawman protocol wouldn't work in practice at the peak of the | |||
infection because of the sheer data requirements. However there are | |||
various cryptographic tricks which are floating around to reduce the size | |||
of the data set.</p> | |||
</div> | |||
<div class="section" id="dp-3t"> | |||
<h2>DP-3T</h2> | |||
<p><a class="reference external" href="https://github.com/DP-3T/documents/">DP-3T</a> is currently one of the | |||
most promising protocols here. It has a low cost variant which satisfies | |||
most of the qualities of the strawman protocol while reducing the amount | |||
of data greatly (to around 1.5MB of data per day for a peak infection rate | |||
of 40.000 infections a day). Additionally it comes with a protocol | |||
extension (âUnlinkable decentralized proximity tracingâ) which improves on | |||
the simple protocol in a few important aspects. Specifically it makes it | |||
significantly harder for an adversary to track or identify infected users | |||
at the cost of higher bandwidth requirements.</p> | |||
<p>A simple version of the protocol is easily explained:</p> | |||
<ol class="arabic simple"> | |||
<li>A device generates a secret key. Each day the user derives a new | |||
version of the secret key by feeding it into a ratchet like a SHA256 | |||
hash function.</li> | |||
<li>Each day the device generates TCNs out of the day's secret key for | |||
instance by using a AES in counter mode. If for instance we want to | |||
switch TCNs every 15 minutes we would need to generate 4 * 24 * 16 bytes | |||
worth of TCNs to have enough for a day.</li> | |||
<li>Devices now broadcast a random TCN for the day for 15 minutes each.</li> | |||
<li>When a device encounters another person and they consider the contact | |||
long enough, they record the approximate time of day and the TCN | |||
encountered.</li> | |||
<li>When a user tests covid-19 positive they upload the secret key of the | |||
first day of infection and generate a new secret key.</li> | |||
<li>Other devices now download the secret key for that user and generate | |||
all possible TCNs locally and check for infection. They only need to | |||
generate 14 derivations of the secret key and the 96 TCNs for each day.</li> | |||
</ol> | |||
<p>In the more complex version the device uploads seeds of the secret keys | |||
for all time windows in the infection window. On the backend server a | |||
<a class="reference external" href="https://en.wikipedia.org/wiki/Cuckoo_filter">cuckoo filter</a> is created | |||
every 4 hours and the seeds are inserted. Because Cuckoo filters have a | |||
small probability of producing false positives parameters need to be | |||
selected appropriately to reduce this risk. The upside is that the sets | |||
of identifiers used by the same user are hidden.</p> | |||
</div> | |||
<div class="section" id="pepp-pt-and-local-governments"> | |||
<h2>PEPP-PT and Local Governments</h2> | |||
<p>So this leads us to <a class="reference external" href="https://www.pepp-pt.org/">PEPP-PT</a>. It would | |||
appear that PEPP-PT is evaluating DP-3T as the reference protocol and | |||
they are going to open source the code with the idea to support local | |||
authorities in implementing their own version. Officially they have not | |||
decided between centralized or TCN approaches yet, but there seems to be a | |||
high chance it will be the latter. The concept is also very simple. | |||
Simple enough that if you want to explain this system to others, there is | |||
also a nice little <a class="reference external" href="https://ncase.me/contact-tracing/">comic strip available</a> that explains it.</p> | |||
<p>If your local government is planning on implementing a covid tracing app | |||
it might be worth directing them towards <a class="reference external" href="https://github.com/Co-Epi">Co-Epi</a>. It already has an implementation | |||
of many of the same ideas in their GitHub repository. If they do want a | |||
centralized approach the Singaporean government Open Sourced their | |||
application under GPL3 under the name <a class="reference external" href="https://bluetrace.io/">BlueTrace</a>. It avoids largely unnecessary cloud | |||
infrastructure from what I can tell.</p> | |||
</div> | |||
</article> | |||
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title: Temporary Contact Number based Contact Tracing | |||
url: https://lucumr.pocoo.org/2020/4/9/tcn-contact-tracing/ | |||
hash_url: 7f71531b565d7a8b0a99100786687cfd | |||
<p class="date">written on Thursday, April 9, 2020 | |||
</p><p>I have already talked here before about <a class="reference external" href="https://lucumr.pocoo.org/2020/4/3/contact-tracing/">privacy preserving contact | |||
tracing</a> to fight Covid-19 but I figured I | |||
give an update to this. I have spent the last week now investigating | |||
different approaches to this and my view has changed quite a bit.</p> | |||
<p>I strongly believe that contact tracing through phone apps is one of our | |||
best chances to return to normal and without losing our civil liberties. | |||
If you want to understand why, have a look at <a class="reference external" href="https://lucumr.pocoo.org/2020/4/3/contact-tracing/">previous post about this | |||
topic</a>.</p> | |||
<div class="section" id="two-fundamental-approaches"> | |||
<h2>Two Fundamental Approaches</h2> | |||
<p>In the previous post I talked in favour of a partially centralized | |||
approach. This was largely because I felt that one of the inherent | |||
problems of any privacy preserving contact tracing system could be | |||
somewhat mitigated. That downside is that a person could always use any | |||
such contact tracing system in a way where they could determine that | |||
another person they met tested positive for covid-19 later. With a | |||
system that has support from a central authority this still cannot be | |||
prevented, but such behavior could be detected as abusive. However I am | |||
not quite convinced that this would just be security by obscurity and that | |||
the more correct way to deal with this is to just fundamentally | |||
communicate to users that this is an inherent property of the system.</p> | |||
<p>So the disclaimer to any app has to be: if you do not want that other | |||
people discover when you will test positive for covid-19 you should not | |||
use any contact tracing apps. Which is also why I strongly believe that | |||
any such system absolutely needs to be voluntary.</p> | |||
<p>So if I no longer believe in favour of the centralized approach, what do I | |||
prefer then? Quite simply put an approach based on temporary contact | |||
numbers, short <a class="reference external" href="https://tcn-coalition.org/">TCNs</a>. These protocols are | |||
fundamentally decentralized and give us some other benefits.</p> | |||
</div> | |||
<div class="section" id="reality-on-the-ground"> | |||
<h2>Reality on the Ground</h2> | |||
<p>What makes application based contact tracing very interesting is that they | |||
take advantage of working on top of a widely deployed piece of hardware: | |||
smart phones. Specifically smartphones which support Bluetooth low | |||
energy (BLE). If you hold an AirPods case close to your iPhone you will | |||
notice that something happens on your screen. BLE is what enables that.</p> | |||
<p>The downside of this is that BLE comes with some restrictions. The two | |||
most relevant ones are the payload size. BLE comes with different modes | |||
and different platforms call this in different ways but the most | |||
compatible and energy preserving modes restrict us to under 30 bytes of | |||
payload. That's not enough to make fancy public key cryptography work | |||
which would be necessary for centralized approaches to play to their | |||
advantages. This is also why systems that currently follow the | |||
centralized approach will typically exchange a short ID and the extra | |||
payload is then actually exchanged through the cloud or <a class="reference external" href="https://en.wikipedia.org/wiki/Bluetooth_Low_Energy#GATT_operations">GATT</a>. | |||
The former makes a system that could be somewhat decentralized much more | |||
centralized.</p> | |||
<p>TCN based protocols instead will exchange just random identifiers instead. | |||
Most TCN based protocols currently suggest between 16 and 26 bytes of | |||
effectively random data which is easier to work with.</p> | |||
<p>Another complexity is that at present iOS devices in background cannot | |||
discover each other. This limitation might be solvable by Apple and it | |||
appears various groups are currently in contact with Apple to see what can | |||
be done. Interestingly an iOS device with the app in background can be | |||
discovered by an Android device so there might be a way to fix this.</p> | |||
</div> | |||
<div class="section" id="tcn-strawman-protocol"> | |||
<h2>TCN Strawman Protocol</h2> | |||
<p>The TCN strawman protocol is the most basic of all these protocols. It | |||
was first written down by the <a class="reference external" href="https://www.coepi.org/">Co-Epi project</a> | |||
and is very easy to explain.</p> | |||
<ol class="arabic simple"> | |||
<li>all mobile phones randomly generate TCNs and remember and broadcast | |||
these.</li> | |||
<li>all mobile phones check against a server which publishes TCNs that are | |||
known to be covid-19 positive.</li> | |||
<li>all mobile phones check their local contact list against the downloaded | |||
list locally for an intersection.</li> | |||
</ol> | |||
<p>Step 2 is the only one where a central system is necessary. For instance | |||
this could be the server of the Austrian Red Cross which publishes TCNs. | |||
Since the TCNs of encounters are only stored on the devices they have to | |||
get on contact with covid-19 tested positive individuals first.</p> | |||
<p>The strawman protocol wouldn't work in practice at the peak of the | |||
infection because of the sheer data requirements. However there are | |||
various cryptographic tricks which are floating around to reduce the size | |||
of the data set.</p> | |||
</div> | |||
<div class="section" id="dp-3t"> | |||
<h2>DP-3T</h2> | |||
<p><a class="reference external" href="https://github.com/DP-3T/documents/">DP-3T</a> is currently one of the | |||
most promising protocols here. It has a low cost variant which satisfies | |||
most of the qualities of the strawman protocol while reducing the amount | |||
of data greatly (to around 1.5MB of data per day for a peak infection rate | |||
of 40.000 infections a day). Additionally it comes with a protocol | |||
extension (âUnlinkable decentralized proximity tracingâ) which improves on | |||
the simple protocol in a few important aspects. Specifically it makes it | |||
significantly harder for an adversary to track or identify infected users | |||
at the cost of higher bandwidth requirements.</p> | |||
<p>A simple version of the protocol is easily explained:</p> | |||
<ol class="arabic simple"> | |||
<li>A device generates a secret key. Each day the user derives a new | |||
version of the secret key by feeding it into a ratchet like a SHA256 | |||
hash function.</li> | |||
<li>Each day the device generates TCNs out of the day's secret key for | |||
instance by using a AES in counter mode. If for instance we want to | |||
switch TCNs every 15 minutes we would need to generate 4 * 24 * 16 bytes | |||
worth of TCNs to have enough for a day.</li> | |||
<li>Devices now broadcast a random TCN for the day for 15 minutes each.</li> | |||
<li>When a device encounters another person and they consider the contact | |||
long enough, they record the approximate time of day and the TCN | |||
encountered.</li> | |||
<li>When a user tests covid-19 positive they upload the secret key of the | |||
first day of infection and generate a new secret key.</li> | |||
<li>Other devices now download the secret key for that user and generate | |||
all possible TCNs locally and check for infection. They only need to | |||
generate 14 derivations of the secret key and the 96 TCNs for each day.</li> | |||
</ol> | |||
<p>In the more complex version the device uploads seeds of the secret keys | |||
for all time windows in the infection window. On the backend server a | |||
<a class="reference external" href="https://en.wikipedia.org/wiki/Cuckoo_filter">cuckoo filter</a> is created | |||
every 4 hours and the seeds are inserted. Because Cuckoo filters have a | |||
small probability of producing false positives parameters need to be | |||
selected appropriately to reduce this risk. The upside is that the sets | |||
of identifiers used by the same user are hidden.</p> | |||
</div> | |||
<div class="section" id="pepp-pt-and-local-governments"> | |||
<h2>PEPP-PT and Local Governments</h2> | |||
<p>So this leads us to <a class="reference external" href="https://www.pepp-pt.org/">PEPP-PT</a>. It would | |||
appear that PEPP-PT is evaluating DP-3T as the reference protocol and | |||
they are going to open source the code with the idea to support local | |||
authorities in implementing their own version. Officially they have not | |||
decided between centralized or TCN approaches yet, but there seems to be a | |||
high chance it will be the latter. The concept is also very simple. | |||
Simple enough that if you want to explain this system to others, there is | |||
also a nice little <a class="reference external" href="https://ncase.me/contact-tracing/">comic strip available</a> that explains it.</p> | |||
<p>If your local government is planning on implementing a covid tracing app | |||
it might be worth directing them towards <a class="reference external" href="https://github.com/Co-Epi">Co-Epi</a>. It already has an implementation | |||
of many of the same ideas in their GitHub repository. If they do want a | |||
centralized approach the Singaporean government Open Sourced their | |||
application under GPL3 under the name <a class="reference external" href="https://bluetrace.io/">BlueTrace</a>. It avoids largely unnecessary cloud | |||
infrastructure from what I can tell.</p> | |||
</div> |
@@ -0,0 +1,103 @@ | |||
<!doctype html><!-- This is a valid HTML5 document. --> | |||
<!-- Screen readers, SEO, extensions and so on. --> | |||
<html lang="fr"> | |||
<!-- Has to be within the first 1024 bytes, hence before the <title> | |||
See: https://www.w3.org/TR/2012/CR-html5-20121217/document-metadata.html#charset --> | |||
<meta charset="utf-8"> | |||
<!-- Why no `X-UA-Compatible` meta: https://stackoverflow.com/a/6771584 --> | |||
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<meta name="viewport" content="width=device-width,initial-scale=1"> | |||
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<title>How Contact Tracing Can Foil COVID-19 & Big Brother (archive) — David Larlet</title> | |||
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<body class="remarkdown h1-underline h2-underline h3-underline hr-center ul-star pre-tick"> | |||
<article> | |||
<h1>How Contact Tracing Can Foil COVID-19 & Big Brother</h1> | |||
<h2><a href="https://ncase.me/contact-tracing/">Source originale du contenu</a></h2> | |||
<p> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0001.png?v=3"/> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0002.png?v=3"/> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0003.png?v=3"/> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0004.png?v=3"/> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0005.png?v=3"/> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0006.png?v=3"/> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0007.png?v=3"/> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0008.png?v=3"/> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0009.png?v=3"/> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0010.png?v=3"/> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0011.png?v=3"/> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0012.png?v=3"/> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0013.png?v=3"/> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0014.png?v=3"/> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0015.png?v=3"/> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0016.png?v=3"/> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0017.png?v=3"/> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0018.png?v=3"/> | |||
</p> | |||
<p> | |||
<a href="https://ncase.me/contact-tracing/comic.zip">Download this comic as a .zip!</a> | |||
</p> | |||
<p> | |||
Sources: | |||
<a href="https://github.com/DP-3T/documents">DP-3T</a>, | |||
<a href="https://github.com/TCNCoalition/TCN">TCN Protocol</a>, | |||
<a href="https://science.sciencemag.org/content/early/2020/03/30/science.abb6936">Ferretti & Wymant et al</a> | |||
</p> | |||
<p> | |||
<a href="https://creativecommons.org/publicdomain/zero/1.0/deed.en">CC0/Public Domain</a> | |||
</p> | |||
<p> | |||
By Nicky Case | |||
(<a href="https://ncase.me/">site</a> · | |||
<a href="https://www.patreon.com/ncase">patreon</a>) | |||
</p> | |||
<p> | |||
With huge help from | |||
<a href="http://carmelatroncoso.com/">Prof Carmelo Troncoso</a> & | |||
<a href="https://people.epfl.ch/marcel.salathe">Prof Marcel Salathé</a> | |||
</p> | |||
</article> | |||
<hr> | |||
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@@ -0,0 +1,46 @@ | |||
title: How Contact Tracing Can Foil COVID-19 & Big Brother | |||
url: https://ncase.me/contact-tracing/ | |||
hash_url: c8a8edb7bc65f4ed6b0edc18010434cc | |||
<p> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0001.png?v=3"/> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0002.png?v=3"/> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0003.png?v=3"/> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0004.png?v=3"/> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0005.png?v=3"/> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0006.png?v=3"/> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0007.png?v=3"/> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0008.png?v=3"/> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0009.png?v=3"/> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0010.png?v=3"/> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0011.png?v=3"/> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0012.png?v=3"/> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0013.png?v=3"/> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0014.png?v=3"/> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0015.png?v=3"/> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0016.png?v=3"/> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0017.png?v=3"/> | |||
<img src="https://ncase.me/contact-tracing/panels/panel0018.png?v=3"/> | |||
</p> | |||
<p> | |||
<a href="https://ncase.me/contact-tracing/comic.zip">Download this comic as a .zip!</a> | |||
</p> | |||
<p> | |||
Sources: | |||
<a href="https://github.com/DP-3T/documents">DP-3T</a>, | |||
<a href="https://github.com/TCNCoalition/TCN">TCN Protocol</a>, | |||
<a href="https://science.sciencemag.org/content/early/2020/03/30/science.abb6936">Ferretti & Wymant et al</a> | |||
</p> | |||
<p> | |||
<a href="https://creativecommons.org/publicdomain/zero/1.0/deed.en">CC0/Public Domain</a> | |||
</p> | |||
<p> | |||
By Nicky Case | |||
(<a href="https://ncase.me/">site</a> · | |||
<a href="https://www.patreon.com/ncase">patreon</a>) | |||
</p> | |||
<p> | |||
With huge help from | |||
<a href="http://carmelatroncoso.com/">Prof Carmelo Troncoso</a> & | |||
<a href="https://people.epfl.ch/marcel.salathe">Prof Marcel Salathé</a> | |||
</p> |
@@ -181,8 +181,12 @@ | |||
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<li><a href="/david/cache/2020/7f71531b565d7a8b0a99100786687cfd/" title="Accès à l'article caché">Temporary Contact Number based Contact Tracing</a> (<a href="https://lucumr.pocoo.org/2020/4/9/tcn-contact-tracing/" title="Accès à l'article original">original</a>)</li> | |||
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<li><a href="/david/cache/2020/c8a8edb7bc65f4ed6b0edc18010434cc/" title="Accès à l'article caché">How Contact Tracing Can Foil COVID-19 & Big Brother</a> (<a href="https://ncase.me/contact-tracing/" title="Accès à l'article original">original</a>)</li> | |||
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<li><a href="/david/cache/2020/1d190443e06aa99b44dd2a4d55b1b58e/" title="Accès à l'article caché">The Secretive Company That Might End Privacy as We Know It</a> (<a href="https://www.nytimes.com/2020/01/18/technology/clearview-privacy-facial-recognition.html" title="Accès à l'article original">original</a>)</li> |