>Google and Apple need to get their act together though, and just provide a contact tracing framework as part of the OS that is compatible, and can have data housed in each country where they see fit.

No. They already have their act together by providing only an API that cannot be abused by authoritarian regimes to do whatever, and keep stupid/badly advised politicians such as my own German government at bay. I hope they keep that line.

The reason Germany switched the approach finally was the public pressure by a) having Google/Apple stay course and b) the German public - learning from journalists and other experts - that there in fact was a less privacy-invasive approach that according to many if not most epidemiologists wasn't any worse either for tracking the pandemic.

I will never touch / install contact tracing if it can be backdoored into global surveilance. Apple has built a reputation for at least trying to preserve some user privacy. Their current proposal keeps it simple, your privacy is preserved and benefits for exposure notification (FAR beyond current horrendous govt efforts in terms of speed of notification etc) are there.

They need to get their act together, and ignore folks trying to backdoor their systems.

It should be noted that your privacy is not preserved if you test positive and need to upload your Daily Tracing Keys to a server. Your broadcast IDs for an entire day can be linked together, making it easier to de-anonymize you. I understand that they use Daily Tracing Keys to reduce the demand of the backend server, but I think it would be better for user privacy if they either reduced the linkable period from a day to say an hour, or used an unlinkable design.

In case you test positive, and we actually have the resources to trace your contacts, your privacy will be gone in todays system for sure.

As you'll have to provide information about your recent contacts to the authorities performing the contact tracing. At least that's how I understand our local law (Germany).

So I don't think its necessarily worse doing it with an App than doing it the old fashioned way. Sure digital traces are always easier to abuse, but then on the other hand, because things get automated, actually less people might get access to your data. Which would be a privacy win.

I believe what's even more important than how we design the app, is how we design the legal framework around it. We do need rock solid laws, having enforceable data retention periods, and that limit access to the pare minimum needed.

Unfortunately, our track record for the design of such laws has not been too good over the last years.

I can assure you that most people, if they were buying drugs or cheating on their spouse, will omit certain contacts from any “manual” tracing effort.

I'm not sure if you intended that to be positive (ie tracing might be more complete in some cases) or negative (ie concerns about not wanting to reveal certain data). I'm going to go ahead and respond to the negative interpretation in case any future readers interpret it that way.

This is true, but I think a DP-3T like protocol (ex the Apple-Google spec) doesn't actually pose much risk here. The hypothetical drug dealer or other illicit contact can receive a notification that they were potentially exposed to someone that was infected, but in general no one else (a police officer, a spouse, etc) will be able to determine who was in contact with who.

In order to link someone to a particular location, you would need to observe their broadcast identifier while they were there and also link their diagnosis key back to them (this is likely to be quite difficult for most actors to accomplish).

In order to reveal a contact between two people, you would either need to do the above for both of them or to observe at least one of them at that location and time in some other manner.

I’m sure the protocol is fully privacy preserving, now. But if we give an inch, the government will take a mile. This is about normalizing self-surveillance and isolating ourselves in response to notifications on our phone. Sure, the tech is privacy-preserving now. But who’s to say an emphasis will remain on privacy in future iterations of the technology?

Personally, I will not opt-in to this technology, and if forced to use it, I will leave my phone at home. It’s a small act of civil disobedience but it’s a necessary one IMO.

It’s alarming to me how so many in tech seem welcoming of, even excited for, this technology. I say this as someone who wrote my senior thesis on a subject related to privacy enhancing technology, so I’m familiar with the ideas.

> It’s alarming to me how so many in tech seem welcoming of, even excited for, this technology.

It gets contact tracing right by accomplishing the goal while yielding almost no ground on privacy and remaining almost entirely offline. In an ideal world, all new technologies would be implemented in such a focused manner without regard for turning a profit.

I'm puzzled by your concern about normalization of self-surveillance; everyone I know has already voluntarily made drastic alterations to their behaviors due to current circumstances. I really don't see what introduction of this technology changes.

> who’s to say an emphasis will remain on privacy in future iterations of the technology?

If people don't object to widespread state surveillance later, would they have objected now? I don't see why a decentralized technology specifically built to prevent surveillance should lead to an increase in acceptance of it.

The difference is that the old system relied on human memory which is fallible, not to mention you can omit details which would lead to further trouble (infidelities for one). In this system the only control a user has is to turn off bluetooth, or leave their phone at home if Apple/Google override the users ability to turn this off.

I think it's up to you to upload the data? It seems like it depends how the app is designed. The protocol doesn't specify it.

The protocol states that it will upload the Diagnosis Keys, a set of Daily Tracing Keys relevant to your exposure. So in short, if this is the case it forces the user to either upload all their keys or none.

I would like to note that a v1.1 has recently been released, my information is about v1.0.

The specification (at least v1.1) contains nothing about uploading keys. The API appears to provide only the minimum required for protocol implementation.

The ENSelfExposureInfoRequest class can be used by an app to obtain diagnosis keys for the previous 14 days. What an app does with those keys is up to whoever implements it.

https://covid19-static.cdn-apple.com/applications/covid19/cu...

That does not seem to line up with their cryptography specification, which is where I am getting my information from. Thank you for mentioning this

I thought only the DTKs are uploaded? That is, you can censor your activity on a day-to-day basis but not on an hourly basis.

Under what circumstances do you think it would be okay for an infected person to hide their contacts? Surely you’re not valuing your marriage over the lives that will be lost in the resulting spread?

If a user is in close confinement with someone they fear will lash out at them if they test positive, for one. Off the top of my head, lets say you take an Uber home and the driver now has your home address, you don't know if they will try and attack you.

This is an example off the top of my head, as other comments in this thread have explained, violence against people who have the virus is happening around the world and is something that must be accounted for in these protocols.

Edit: a link to a story from another comment (https://www.washingtonpost.com/world/the_americas/coronaviru...). I hope you can see that this technology can worsen this.

The system doesn’t say who your affected contact is, only that you have one. The driver has no way of knowing it was you.

If you have a Bluetooth receiver logging the different IDs you've come in proximity with and when, its easy to deduce who the positive user is by who you were in proximity of at that time.

This is why the Framework only reports matches with a very coarse granularity.

At what time? It could be any user you’ve been in contact with for two weeks.

Well, let's keep in mind it is decentralised, so only people who have been in contact with you can correlate it with your location at a given time in the past. Not the whole world nor a central authority.

And even is someone goes to that extent to track your identity down, I am not sure that local de-anonymisation is a problem. This is not something like HIV. I don't think there is any social stigma to catching the coronavirus. If you catch it you should self-isolate, and it will be obvious to the people around you that you got it. And if you don't want to self-isolate and want to hide it, what is the point to self declare that you got contaminated on the app in the first place?

> I don't think there is any social stigma to catching the coronavirus.

"In Mexico, Colombia, India, the Philippines, Australia and other countries, people terrified by the highly infectious virus are lashing out at medical professionals — kicking them off buses, evicting them from apartments, even dousing them with water mixed with chlorine."

https://www.washingtonpost.com/world/the_americas/coronaviru...

...and these are cases where the victims don't even have the virus.

Disease has always carried stigma. We tend to lash out at things we don't understand. History has seen everything from leper colonies to menstruating women herded into tents.

You or I may be able to rationalize it and say "well, shit, the test was positive-- time to self-isolate" but plenty of plebes will use it as cause to incite a witch hunt, especially if a loved one dies from it and transmission is attributable to you.

OK, that's a fair point, but it would take someone uneducated that believes in the stigma to also be a tech wiz to collect and correlate the data. Presumably the app won't tell you when and where the contact happened (and if so, no implementation of contact tracing is anonymous since the app won't know that you were in a busy bus full of strangers or in a small office with a single colleague).

> it would take someone uneducated that believes in the stigma to also be a tech wiz to collect and correlate the data

Not quite. It takes a wiz to collect and correlate the data, yes. What happens to that data after that? For it to be useful, it's going to get stored somewhere. All it takes is an uneducated clerk or bored intern with access to go snooping around the de-anonymized data to compromise anybody implicated.

And this does happen routinely.

* Facebook, Uber and Google have all had problems with plebes (and tech wizzes!) with god-tier access doing inappropriate things with sensitive data.

* Bored data entry clerks with access to the credit reporting database routinely snoop on neighbors', exes' and celebrities' credit reports in spite of federal law.

* Revenge porn is such a thing that rule 34(a) ought to be that if you produce nudes, your confidant or Geek Squad/iRepair technician will post them on the internet.

* Look at how often people get doxxed by employees leaking customer PII onto reddit and 4chan, then look at how fast the mob descends on people innocent of any actual wrongdoing.

* We've seen a secretary get her hands on the Pepsi formula and try to sell it to Coca-Cola.

* The people living in the geographic center of America continue to receive death threats and harassment because of a flaw in outdated MaxMind databases that attributes ungeolocatable IPs to their location.

* There are people who refuse to participate in the census because of what certain cults of personality have done with such data.

Any chain of confidentiality is only as strong as its weakest link. You presume far too much intelligence and rationality on the part of humanity. Never forget that half of Americans wanted a belligerent narcissist to be "leader of the free world," and he still has supporters despite publicly recommending anti-parasitics and Lysol douches as solutions for a global viral pandemic.

Sensitive data is not created and left to decay in an underground bunker in Yuma. Despite its practical uses, at some level it will be exposed to individuals who lack discretion and will be exploited to malevolent ends.

Not once in human history has it worked out any other way!

The deanonymized data doesn't exist except on your own device.

It's a bit more complicated than that. What's being suggested here is that it would be possible for a bad actor to observe all Bluetooth activity over a large area. They could then use a diagnosis key to reconstruct someone's path through this monitored area, and then deanonymize that person by combining their path with other data sources. Later, an uneducated and hostile individual might somehow gain access to this deanonymized data and abuse it.

Couldn't they do that for anyone with bluetooth on, whether or not they're using the app? I get that knowing they have Coronavirus might make them a bigger target, though

Sort of.

If you enable the framework but never test positive (and thus never publish any of your keys), it's no different than if you had just kept Bluetooth on all the time.

If you enable the framework, later test positive, and choose to publish your diagnosis keys, each key can be used to link all your rolling identifiers together for the corresponding time period (nominally 24 hours). Contrast this with a randomizing Bluetooth implementation, which never intentionally reveals anything that would allow the different MAC addresses to be linked.

Of course, Bluetooth MAC address randomization itself is trivial to defeat for a reasonably capable and motivated adversary. If they can plant a bunch of radios for the purpose of tracking you, why can't they also use cameras?

That would work if there's just 1 person who is crossing the path, and you're able to physically identify them. If it's a crowd of people, you won't know who was what device unless their device is immediately next to the evil antenna. This isn't very realistic in practice, and is very unlikely to become common place world-wide. However, the virus IS already world-wide, and is a giant threat to many.

> If it's a crowd of people, you won't know who was what device unless their device is immediately next to the evil antenna.

Actually that's not true for the situation I described.

The bad actor would be able to connect any of your broadcast identifiers they observed back to each other via the diagnosis key that you published. Assuming they have a number of nodes monitoring Bluetooth traffic over a broad area that you passed through, they will be able to reconstruct the path you traveled over time.

For a naive implementation, the resolution of this reconstruction would depend on the spacing of the nodes. For a more advanced implementation, other data could be integrated to drastically improve it. Remember, your Bluetooth device is a broadcasting radio at the end of the day.

As to the likelihood of such things becoming commonplace worldwide, do bear in mind that many devices now periodically randomize their Bluetooth MAC addresses due to real world examples of tracking. Thankfully in this case it would only be possible to compromise the privacy of those who tested positive, and only within a singe 24 hour period (ie the daily tracing key rotation time frame) at that.

Yes, I agree this is true if someone was to go to extreme efforts. It seems to me personally quite unlikely, especially since the governments are already the ones who distribute the apps, and at least it seems in the initial implementation, are the ones who confirm your status.

I'm much more concerned about reducing COVID-19 to save millions of lives.

People who are educated tech wizards can also have the same stigma. There are many factors at play in places that have more diversity and existing problems between communities (like race, religion, class, etc.). Hopefully, like you said, the app won’t tell you when and where the contact happened. But we still need to make sure that we have as much privacy protection as possible while making this useful.

> I don't think there is any social stigma to catching the coronavirus.

Sadly, this is not true in India. Infected people have been threatened by their neighbors and friends with death. Infected people have also been harmed. Doctors, nurses and healthcare workers who have been caring for COVID-19 patients have been evicted from their houses or physically harmed (the latter forced the government to bring an emergency law providing for stringent punishment for those who attack healthcare workers).

I’m guessing that there will be a social stigma depending on the culture as well as other factors like the mortality rate (if your area has a higher mortality rate, then you’d likely hate infected people and take matters into your own hands).

Humans can very quickly develop irrational fears and react on that.

So there is a huge need to preserve the privacy of those infected.

So all of the tokens are being put on a central server. Today, governments use WiFi and Bluetooth to track traffic. It is not far fetched to see that your commute from point A to B could be tracked using Bluetooth receivers in transit stations.

This technology is currently being used to track people today. The use of Bluetooth address randomization does not do a sufficient job to prevent this, the only option is to not use Bluetooth.

It is important that people are aware of these risks. I am fortunate to live in a place where I can live my life without scrutiny from the government, but not all are afforded such a luxury.

Even if they do that, they can only track the people who self report as contaminated for the period during which the self reporting applies (i.e. n days before testing positive). Not before, not after.

But I just can't think of a system that achieves contact tracing while no one having any idea of the whereabouts of a person who self declares as contaminated. At one point the person who self declares has to volunteer to disclose some information.

I think its important to give the power to the people by allowing them to omit tokens from sensitive time points. In the current protocol, that means losing a whole days worth of contacts. If you reduce the period to an hour, you still allow people to share the contacts made on their commute or their lunch break without divulging or tracing them back to more sensitive time periods they don't want to be traced back to.

That’s one side of the ethical question, but what about the other side, what about the people who have been in contact during the period where the infected person would rather not have its location disclosed?

And it is a bit theoretical, as the authorities who have the capability to track your blutooth across the city have many other ways to track you (starting by calling your phone service).

What I object here with the NHS is the creation of one more tracking database with the explicit intention to let some researcher roam through it to find something interesting.

I appreciate you looking at the other side. To explain my view point, in this system it seems like all of the risk is put on the infected party who reports themselves. By decreasing the level of control they have, I believe you will see a decrease in the number of adoptions. It is valid to think about the non-infected user wanting to have this information, but today they don't even have this information so to even know they were exposed on their commute is above and beyond what is in place today.

I guess my original comment is a bit vague. When I look at these protocols I am interested in how large scale adversaries (Nation State) would use this technology, but also small scale adversaries (day-to-day person you are not friendly with). I think its also important to note as others have, that being outed as having the virus does put people at risk of violence in some places.

Telling people when they've been exposed is not a kindness we might extend from the goodness of our hearts when convenient. It's something we must get right, every time, or the conditions that require lockdown today persist until vaccination. We cannot afford people out and about making untraceable contacts three weeks for now, any more than we could three weeks ago.

Every person is a danger to society until this is over. Release is out of the question. The choices here are continued incarceration, or parole.

I can sort of imagine a libertarian solution here, with truth in labeling: as long as I can tell before I get within six feet of you whether you share a connected component with any conscientious objectors, then I can make my own decision about risk. But I cannot imagine that many public places would permit entry to such people.

> I don't think there is any social stigma to catching the coronavirus.

Maybe not. But there is definitely a social stigma about certain activities, like meeting your drug dealer or cheating on your spouse, which would be revealed through automated contact tracing.

It would only be revealed to your drug dealer or to whoever was in the vicinity.

And to the authoroties, who then promise to not violate that promise.

Except they refuse to be limited by cryptographic means to that.

Why? Because they demand the ability to change their promise in the future ... exact details to be specified. Perhaps “solving drugs” with contact tracing. At which point they have your data, you have zero control, and “your honour we can prove he lied: he was close to that drug dealer 5 times. Further details (such as that this happened in the train station and 5000 other people were also close) cannot be confirmed because that would violate privacy”.

This is the government that got caught letting police officers stalk their ex for 2+ years and then initially arrested the victim for more than 2 weeks when caught. Let’s not pretend they’re above doing this, especially since it’s become increasingly clear this contact tracing is the police’s wet dream.

With any luck, we will create stigma a hundred thousand times more powerful against deliberately helping the virus spread.

Try to walk through a public place with one of the medical masks (if you can source them). Practically everybody moved as far as they possibly could.

But yeah there has been lots of stories about medical personnel who where thrown out of their rented places because of the fear of the virus.

This is almost never actually the case. Your daily keys are random, so the only way to know it's you is for someone to monitor bluetooth devices near by, and associate those keys with a physical identity... which becomes very difficult unless there's only one other person you come into contact with. In practice, it provides about the best anonymity you could ask for.

Valid point. DP3T (in one configuration) adresses this and lets you filter out certain parts that you do not wish to disclose. Thus, this then requires you to upload all broadcast identities used in the relevant timeframe, but because of space-related issues is then „compressed“ using a Cuckoo-Filter. This, however, yields false-positives. To eliminate those to a managable amount, it further requires more space.

So, this has a tradeoff. Personally I don‘t think that linking multiple IDs in a day is a big intrusion of your privacy (and remember, it‘s only disclosed to anyone for the timeframe that is epidemologically relevant) - full de-anonymization still requires some second channel, such as cameras or the like - which can be linked together without those Broadcast IDs anyways.

The thing with Bloom/Cuckoo filters is that you can play around with the parameters and, for example, provide a set of filters for a day in such a way that the app users can do a binary search.

It never provides a false negative so all positives can download their set-up filters until they're satisfied.

The filter that DP3T are describing isn't that much bigger than the DTK set anyway.

The unlinked DP-3T is one extreme, there is a happy medium if developers don't want to use Cuckoo Filters or Bloom Filters due to false positives, which is to decrease the linkable period. If the period was an hour, people could freely share legitimate tokens for their commute, but hide the ones where they had an hour long 1-1 with their manager.

It's hard to test positive given the extremely limited supply of tests and all the effort you'd have to go through to get tested. I really can't imagine anybody willingly testing -more so with new invasive tracking- unless they are really ill and in need of medical attention.

The issue is, if your putting the risk on infected users, what is the benefit to them to release their tokens? They are already at risk, this just makes them bigger targets.

The recorded broadcast IDs can be linked together, but only if they are somehow gathered from all of the devices that have been near you. As far as I can tell, the spec doesn't include recorded broadcast IDs ever leaving the device.

If I keep my phone in a RF blocking bag and remove it only when needed I will have some semblance of privacy. I don't care about push notifications.

> Google and Apple need to get their act together though, and just provide a contact tracing framework as part of the OS that is compatible, and can have data housed in each country where they see fit. It should be optional for people, but it should be part of the OS, and it should just be presented to the countries as ready to go with just a little bit of integration. That way we can force everyone to respect user privacy and not do sketchy contact tracing apps.

I think that's a terrible idea. Think about how somebody can mark themselves as being infected. Normally you'd want this to be authorized by a doctor or similar, or maybe just by reporting symptoms if the situation is dire.

Google and Apple rightfully did not want to be involved with these decisions, they just want to provide a way to detect contacts via bluetooth while still mandating preservation of their users privacy.

Parent said a framework. Technically, the framework could be designed in such a way that they whitelist apps or agencies that can do that. Or you’d be given a code to authenticate the results and so on.

Sure, but look at how much governments resent the current limitations already. If they started mandating how doctors authenticate against the app and other processes that are wildly different between countries, they might end up with no countries using their framework.

That's exactly what's happening.

>Google and Apple need to get their act together though, and just provide a contact tracing framework as part of the OS that is compatible

That's exactly what they're doing.

The timeframe for the Apple-Google solution is unclear. I’ve seen “later this year” mentioned rather than days, weeks, or months.

The official timeframe has been 'May' ever since the original announcement. First version of the API is now reported to be available on April 28th:

https://9to5mac.com/2020/04/23/apple-contact-tracing-april-2...

I originally heard May, now it's being suggested that it's this week or next.

My advice to the NHS developers would be: don’t let perfect be the enemy of good.

The effectiveness of a contact tracing app scales with adoption. A sketchy, battery-draining implementation with questionable privacy may not see widespread adoption.

> A sketchy, battery-draining implementation with questionable privacy may not see widespread adoption.

A battery draining implementation may be the best they can do by themselves, and, from past form, the lack of privacy is a feature and not a bug.

They’ve really gone out of their way to adopt a centralized solution, when a decentralized solution would be better in almost every way.

I doubt the developers have much input, will be some incompetent dinosaurs in middle management pushing for this.

> Palentir

Big warning here, i know they tried persuade multiple countries, but I'm so glad to be living in Europe. ( They do have some business here though)

https://www.bloomberg.com/news/articles/2020-04-01/palantir-...

At least Germany is using the best possible solution.

I'm pretty sure a fair amount of bribe/lobby money is involved in the US.

Can't find much sources about them in Europe currently :

https://ec.europa.eu/transparencyregister/public/consultatio...

>can have data housed in each country where they see fit

Hadn't thought of this until you mentioned it, but having it only work within a country could significantly hinder the ability to trace imported cases (ie, cases from travelers).

If the data is housed in country-of-citizenship, then travelers would not notify people they contact while abroad.

If the data is housed in country-of-current-location, then people who test positive while abroad might not notify people in their home country whom they contacted before leaving. There might also be failures cases when they return home, but those could probably be solved with careful implementation.

Regardless, this seems like a case where a single international, globally-accessible registry is useful. And therefore privacy becomes a very important concern.

What travelers.

Residents of a country where they are not a citizen, like me (American living in Germany). A year from now, I might decide to visit my home country, and even be allowed back in, and if I stood in the customs line in Amsterdam near a Frenchman who hung out with someone in Montreal who turned up positive, it would be in everyone's interest for me to know I was exposed.

Even traveling between Munich and Nuremberg, a one hour trip, I might be on a train near an Austrian who saw no reason to leave Munich during all this heading up to Berlin to finish a consulting contract, but a week ago had been in a meeting with a German who turned up positive. Our Austrian consultant would have been allowed to stay this past "shelter-in-place" month if she had a lease on an apartment and had registered it as her primary residence - no residence permit required, as she's an EU citizen. Again, it would be in everyone's interest for the three of us (and everyone we had much time around) to know about when the exposure took place and that we might need to self-quarantine/be tested.

Fair point right now, but that's not going to be the case forever. And once things start to open up again and cases are less common, this kind of contact tracing will become even more important to track down new outbreaks.

The ones who live in Germany and work in France. Replace with most European countries.

I think travelers might be managed by a more "high touch" quarantining process in most countries to ensure they cannot spread the virus.

Note that DP-3T and PEPP-PT are both privacy "preserving" protocols. They make different trade-offs between threat models and ultimate levels of privacy, but these are both vast improvements over the pervasive centralised geolocation data collection used in China and South Korea.

I think DP-3T is the better choice, and Germany has clearly come to that decision as well (helped, no doubt, by the fact that this is the protocol that will receive API support) but I think it is reasonable to come to the conclusion that PEPP-PT is better.

Depends from who you want to be kept private. I've a hard time describing PEPP-PT "privacy preserving" the same way as DP-3T, especially as far as the central server is concerned and the blind trust I must put in it, but I admit this is still better than China like solutions. As for the trade-offs concerning privacy, it is true that DP-3T is not perfectly more private than PEPP-PT from a theoretical point of view (and nor the inverse), but this concern seems weird from a practical point of view and I have a hard time figuring out practical attacks doable against the public with DP-3T but not with PEPP-PT that would not be the sign of far worse problems...

> Google and Apple need to get their act together though, and just provide a contact tracing framework as part of the OS that is compatible, and can have data housed in each country where they see fit.

Absolutely not. That has way too much temptation for any government to utterly abuse. Simply creating it is opening a pandora's box and should not be done.

How can governments or individuals check if its implemented the way they claim? Phones are black boxes, read source code and hope it is what it reads?

Apparently you just need to trust GCHQ, who advised them. There isn't another agency privacy minded people would rather trust (apart perhaps its US and Chinese equivalents).

>All of this contact tracing can be done in a privacy preserving way.

Explain how having every person you're in contact with being tracked by governments and corporations can be done in a 'privacy preserving way'. The very concept of contact tracing is probably the greatest violation of privacy I've seen proposed yet.

Read the spec, but in a nutshell you only report your tokens if you test positive. Then other people check to see if they have seen any reported tokens using a clever algorithm that doesn't involve them reporting all the tokens they have seen.

The central authority just has a list of tokens from infected people. A corrupt central authority could also massively deploy token recorders across an area and then see when and where the infected people were seen, but governments already have that capability just from the cellular systems.

Simple. The system doesn't track every person you're in contact with.

A simple method is to have phones directly exchange random numbers over bluetooth. If and only if someone tests positive, they publish their phone's recent random number transmissions. All phones download all published random numbers (just random numbers, no personal info) and see whether they've received any of them via bluetooth.

This way the phone knows whether it's been in contact with someone who tested positive, but nobody else knows. Since the user has a strong incentive to get a covid test at that point, that's fine.

It's totally possible to create an anonymous and decentralised contact tracing app that does not share private data. That is what Apple-Google are working on, and what projects such as D3P-T, or my hobby contact tracing app [1] are trying to achieve.

---

[1] https://github.com/RaphaelJ/covid-tracer/blob/master/README....

Serious question -- have you looked into it at all how this works?

What is the issue with privacy?

The point is to get a list of close contacts, if needed (someone has tested positive), for a limited period of time (until the epidemic has ended).

The privacy issue is minimal, certainly compared to the situation we are in.

Do you really think that the government will go over these data to find out that you tend to have close contacts with your neighbour's wife very often? Let's keep a sense of proportion and let's calm down. This is getting very irrational.

Anyway, since they do not seem to be willing to make contact tracing mandatory, these apps will remain a curiosity until this is over. Then historians will be able to debate whether this was all a distraction or a costly lack of political courage.