A list of issues that make contact tracing an impractical solution in the real world, from trolling others to cheating to insufficient adoption

There have recently been several proposals for pseudonymous contact tracing, including from Apple and Google.

Light Blue Touchpaper 2020-04-13 Ross Anderson

Context & Ripple Effects

Apple and Google's pseudonymous Exposure Notification proposal arrived as the leading answer to centralized tracking fears, but this Light Blue Touchpaper post catalogs why the design breaks outside the spec: users can troll others with fake pings, cheat the system, and — most fundamentally — too few people opt in for it to matter. It lands two days after The Verge documented the limits of Bluetooth-based voluntary tracing, including potentially large numbers of false positives.

Apple had already begun patching one of the listed failure modes, saying apps can weigh duration of proximity when deciding what counts as an exposure event to cut false positive pings. The critique matters because it tests whether a protocol designed around privacy can survive adversarial and indifferent users at population scale.

First-order effects

Developers and health authorities building on Apple and Google's API inherit the listed problems directly: trolling, cheating, and insufficient adoption are design constraints they must engineer around, not edge cases.

Second-order effects

With voluntary uptake unreliable, governments push ahead anyway — dozens of tracking apps are in use or development despite security, privacy, and effectiveness concerns, fragmenting the ecosystem the platform vendors tried to standardize.

Third-order effects

A state-by-state US rollout compounds the flaws into structural ones: inconsistent implementations threaten interoperability and create uneven security and privacy baselines across the country, leaving the platform duopoly as the de facto arbiter of what public-health tracing technology is allowed to do.

The trend: Pandemic contact tracing is consolidating around Apple and Google's exposure-notification layer while its real-world effectiveness stays hostage to voluntary adoption and abuse resistance.

Discussion

@raistolo Stefano Zanero on x
Unsurprisingly, ⁦@rossjanderson⁩ hits a lot of things I also worry about in this blog post. The only thing I marginally disagree with him on is that we do not need CT for the current epidemic wave. True, but we will need it in a short while. https://www.lightbluetouchpaper.org/ .…
@jamescrabtree James Crabtree on x
This is persuasive on the limitations of contact tracing apps - not least the bit on whether people will actually trust the information the app provides, especially if it involves another 14 days at home https://twitter.com/...
@chaosupdates @chaosupdates on x
Ross Anderson crystal-clear on intrusive systems like Contact Tracing Apps: What we need is a radical redistribution of resources from the surveillance-industrial complex to public health https://www.lightbluetouchpaper.org/ ... #Covid19
@fukami @fukami on x
Great piece by @rossjanderson about tracing apps and what's likely to work and what not “We must call out bullshit when we see it, and must not give policymakers the false hope that techno-magic might let them avoid the hard decisions” https://www.lightbluetouchpaper.org/ ...
@shashj Shashank Joshi on x
Contact-tracing apps: “The performance art people will tie a phone to a dog and let it run around the park; the Russians will use the app to run service-denial attacks .... little Johnny will self-report symptoms to get the whole school sent home.” https://www.lightbluetouchpaper…
@shashj Shashank Joshi on x
“Bluetooth also goes through plasterboard ... The bluetooth app will flag up not just the others in the room but people in the next room too.” https://www.lightbluetouchpaper.org/ ...
@shashj Shashank Joshi on x
“If the app's voluntary, nobody has an incentive to use it, except tinkerers and people who religiously comply with whatever the government asks. If uptake remains at 10-15% as in Singapore, it won't be much use and we'll need to hire more contact tracers” https://www.lightblueto…
@jatorre Javier de la Torre on x
I am getting scared of all these cryptographers now saving the world with contact tracing without privacy issues... This is going to delay solutions a lot by adding noise to decision makers. This blog post summarizes it great https://www.lightbluetouchpaper.org/ ...
@johnwilson John S. Wilson on x
The premises in this are flawed. I think many people will use the Apple/Google contact tracing app bc they want to know if they've come in contact with someone who has tested positive. Also this isn't about a perfect solution—none exists. This is about an arsenal that can help. h…
@alexstamos Alex Stamos on x
Combined with the fact that we are approaching 30 days with most corporate laptops not talking to a domain controller (or on-prem config management), this will be a fun couple of months for malware.
@einsteinsattic Phil Booth on x
Seriously folks, if you've not read @rossjanderson's piece yet, pour yourself a stiff drink and do so: https://www.lightbluetouchpaper.org/ ... In these times more than ever, we need his #calm, #considered & well-#informed #clarity.
@tobywalsh Toby Walsh on x
We must call out bullshit when we see it, and must not give policymakers the false hope that techno-magic might let them avoid the hard decisions https://www.lightbluetouchpaper.org/ ...
@ruskin147 Rory Cellan-Jones on x
https://www.lightbluetouchpaper.org/ ... The NHS is developing a contact tracing app which could be key to ending lockdown - but @rossjanderson says it may be a blind alley and we “must not give policymakers the false hope that techno-magic might let them avoid the hard decisions…
@ctbeiser Chris Beiser on x
i usually don't RT threads to debunk them but this one is particularly bad and dumb point one is about a decrease in privacy. if I have coronavirus, allowing the last three days of my bluetooth presence to be correlated together doesn't really sound like the worst. https://twitte…
@koryodynasty Raphael Rashid on x
Contact tracing & related websites were deployed months ago in S. Korea when cases were still only a handful. Now that over 10,000 people have died in the UK, it “confirms plans for an app”. Asia was giving everything on a plate well in advance. https://www.bbc.com/...
@ehrc @ehrc on x
“We support the use of technology to save lives during the pandemic. At the same time it must have the appropriate safeguards in place to protect people's privacy and data.” We are ready to advise the NHS on its new Covid-19 contact tracing app. More: http://socsi.in/VrLA2 https:…
@mattk Matt on x
Needs to be adopted by everyone or this will not work. And if this is how we come out of the quarantine, it will have some interesting consequences. https://twitter.com/...
@libertyhq Liberty on x
This has serious implications for privacy & our relationship with the State. 📵 privacy must be a priority 📵 info must not be shared unnecessarily w/ third parties 📵 data must be deleted ASAP 📵 transparency & clear communication vital to reassure public https://www.bbc.co.uk/...
@bipolarblogger @bipolarblogger on x
NOW we want to contact trace? https://twitter.com/...
@adrianhon Adrian Hon on x
Apparently this was in the works *before* Apple and Google's announcement, which actually shows NHSX's hubris. Without those hardware hooks, hard to see any apps working well. https://www.bbc.com/...
@bbcnews @bbcnews on x
UK confirms plan for contact tracing app to warn users of recent proximity to someone suspected to have coronavirus https://www.bbc.com/...
@hare_brain Stephanie Hare on x
“Experts say the ‘track and trace’ concept [of the NHS app] only works effectively if 60% of people adopt it.” How to get people to install the app? Tell them that re-entry into society is conditional on installing it. So...opt-in (but not really!) https://www.thetimes.co.uk/...
@leokelion Leo Kelion on x
Scoop: The government has confirmed plans for a contact tracing app - we have new details about how it will work with both yellow and red alerts, and plans for tests in the North of England. https://www.bbc.co.uk/...
@lindayueh Linda Yueh on x
NHS mobile phone app would trace users who have come into contact with infected people, alerting them to get tested. Combined with vast expansion in testing (ministers claim will hit 100k a day by the end April), app is a central plank in ending lockdown. https://www.thetimes.co.…
@bensfletcher Ben Fletcher on x
Other than there being no chance the Government won't use the data for other things, alerting people to get tested doesn't really solve anything if the can't actually get tested https://www.thetimes.co.uk/...
@thesundaytimes @thesundaytimes on x
Ministers have ordered the creation of an NHS mobile phone app the government hopes will help end the coronavirus lockdown. https://www.thetimes.co.uk/...
@robwilson_rdg Rob Wilson on x
It's a shame smaller UK tech companies aren't getting much traction with Government. We need to encourage UK innovation more than ever....for jobs. We are going to be 3/5m unemployed. NHS phone app holds key to lifting UK's coronavirus lockdown | News https://www.thetimes.co.uk/.…
@marietjeschaake Marietje Schaake on x
Thread from one of the world's best cryptographers on the contact tracing app frame by Apple/Google ↘️ https://twitter.com/...
@sedyst SedaG on x
Privacy analysis on decentralised apps changes when tracing apps track globally, and are not interoperable instances managed by different organisations/government entities but global infrastructure. Not sufficient to analyse protocol only and here you start seeing the difference.…
@accessnow @accessnow on x
Tech companies are using large amounts of confidential UK patient information in a data-mining operation that is part of the gov's response to the #COVID19 crisis One of the firms, Palantir, is known to have built tech that enabled #HumanRights abuses https://www.theguardian.com/…
@rupertmyers Rupert Myers on x
UK government using confidential patient data in coronavirus response Not only is the Guardian's trust an *investor* in this company but the editor sits on the board that invested in it, and now it's mining confidential patient data. https://www.theguardian.com/ ...
@andywigmore Andy Wigmore on x
Shocking cock up story by @PaulLewis about the owners of the @guardian who own a company that's using patient data to model ‘herd immunity’ and old Codswallop @carolecadwalla is livid...obviously her editor @KathViner is fine with this (she sits on the board of said company) lol …
@libertyhq Liberty on x
“Whitehall source said they were alarmed at the unprecedented amounts of confidential health information being swept up in the project, which they said was progressing at alarming speed and with insufficient regard for privacy, ethics or data protection.” https://www.theguardian.…
@umairh @umairh on x
Note how they were also involved with the “herd immunity” aka...let them die...strategy https://twitter.com/...
@carolecadwalla Carole Cadwalladr on x
Shocking story by @PaulLewis & team. @Guardian has seen documents showing govt using Peter Thiel's Palantir's & NHS patient data to model ‘herd immunity’ week after policy supposedly dropped https://www.theguardian.com/ ...
@thattimwalker Tim Walker on x
UK government using confidential patient data in coronavirus response with help from Palantir, the US big data firm founded by the rightwing billionaire Peter Thiel. https://www.theguardian.com/ ...
@gladstein Alex Gladstein on x
“Technology firms are processing large volumes of confidential UK patient information in a data-mining operation that is part of the government's response to the coronavirus outbreak” https://twitter.com/...
@rowlsmanthorpe Rowland Manthorpe on x
Lots of useful details in this Guardian piece on the NHSX data store Two questions: 1. This data use is entirely defensible, so why didn't NHSX just come out and explain what they were doing at the beginning? 2. Why did Faculty communicate via lawyers? https://www.theguardian.com…
@paullewis Paul Lewis on x
We've seen documents revealing how the American big data firm Palantir and British AI company Faculty are helping build an “unprecedented” UK government database to help respond to the coronavirus outbreak. https://www.theguardian.com/ ...
@benadida Ben Adida on x
1/ Last night, I spent some quality time with the Apple docs on the new contact tracing protocol and APIs they and Google are preparing. I'm quite optimistic about this effort. Here's why.
@moxie Moxie Marlinspike on x
So it takes BTLE privacy a ~step back. I don't see why all of the existing beacon tracking tech wouldn't incorporate this into their stacks. At that point adtech (at minimum) probably knows who you are, where you've been, and that you are covid+.
@shortstein Thomas Steinke on x
Bluetooth LE has a range of up to 100m/300ft. So bluetooth-based COVID-19 contact tracing will collect excessive contacts. False positives will lead to alarm fatigue. 🚨😴 The obvious solution is to record signal strength, but the @Apple/@Google API does not provide this info. http…
@carnage4life Dare Obasanjo on x
Although Apple & Google's have done a commendable job making their contact tracing APIs private, in reality they'll be ineffective if anonymous. Many people won't self quarantine if an app tells them to unless there some enforcement. See Taiwan/Singapore. https://www.theverge.com…
@profwoodward Alan Woodward on x
When considering whether the new NHS corona app is the best exit strategy may I recommend you read @rossjanderson piece here https://www.lightbluetouchpaper.org/ ... especially what proper contact tracing requires.
@moonalice Roger McNamee on x
Excellent post by EPIC advisory board member Ross Anderson on contact tracing in the real world. https://www.lightbluetouchpaper.org/ ...
@kaifulee Kai-Fu Lee on x
Opt-in contact tracing won't work. If 10% people opt-in, 50% always-on bluetooth, 40% people infected voluntarily report, then only 10%*10%*50%*40%= 0.2% pairwise contacts get reported. Am I missing something? https://twitter.com/...
@arunmsukumar Arun Sukumar on x
“in the months after the API is complete, the companies will work on building tracing functionality into the underlying operating system, as an option immediately available to everyone with an iOS or Android phone” https://www.theverge.com/...
@hatr Hakan on x
Ross Anderson quite skeptical whether the tracing-app is going to work. He raises several issues (trolling, social interactions, false-positives) and ends with a plea to redistribute “resources from the surveillance-industrial complex to public health” https://www.lightbluetouchp…
@eugenegu Eugene Gu on x
Google and Apple's contact tracing technology has big implications for privacy rights and freedom. While it may be useful for tracking sick contacts during the coronavirus pandemic, this same technology can be used to persecute political dissidents in a surveillance police state.
@fredabrahams Fred Abrahams on x
Important @ACLU paper on the limits of location tracking in an epidemic. THREAD 1/6 https://www.aclu.org/... https://twitter.com/...
@malteengeler Malte Engeler on x
“Why has surveillance become the only device through which we can effectively act?” Open letter to the #DP3T GutHub. #Corona #Tracking https://github.com/...
@michaelossmann Michael Ossmann on x
This is a very good summary of concerns about the Apple/Google Bluetooth contact tracing system. I was musing about an identical system a few weeks ago and for these very reasons chose not to propose it publicly. Marketing this as “privacy-preserving” is problematic. https://twit…
@bradlander Brad Lander on x
But even beyond the privacy, feasibility, and enforcement concerns (and there are many), it's not clear bluetooth apps will really work. So we will need to hire a lot of people to work on contact tracing. By definition, this is a local & state effort. https://www.theverge.com/...
@onekade @onekade on x
ACLU comment on the Apple/Google contact tracing scheme https://www.aclu.org/...
@antoniocasilli Casilli on x
It seems that the Apple/Google solution has the same privacy problem as other proximity tracers: it's anonymous as long as you are not positive. Moreover it'll most likely be linked to geoloc data+risk of linking to adtech+possibility of proximity “pranks” https://twitter.com/...…
@mikarv Michael Veale on x
I really welcome the proportionate API moves, and the fact the proposed A-G collaborative protocol is decentralised is good. But going forward societies and communities need to have much more say in what gets put in operating systems, and how they can refuse it. https://twitter.c…
@zackwhittaker Zack Whittaker on x
Earlier this week, the ACLU warned about the limits of using location tracking during the coronavirus pandemic. Made some really thoughtful points. Would be curious to see what @granick and @jaycstanley think about this latest effort. https://www.aclu.org/...

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