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Comment by grujicd | Hacker News Reader

This is very sad development for me, Djokovic's countryman who really bought his story. Nut facts are facts.

I can share my own (positive) test, which confirms timestamp and id theory. My test was taken on the 7th January, it was a rapid test, not a PCR. But it's in the same government database:

https://pcr.euprava.gov.rs/validate.php?cqcode=1641591150Q!A...

Timestamp: 1641591150, which translates to GMT: Friday, 7. January 2022. 21:32:30. That seems to be right, it was taken earlier on the 7th and probably entered later to the central database.

Also, ID of my test is: 7601263. Djokovic IDs are 7371999 (16/12 test) and 7320919 (22/12 test).

It really looks like IDs are incremental, and that his test that was supposedly taken on the 16th was taken on the later date.

One consolation fact is that he wasn't positive when he took photos with kids on 17th.

EDIT: I messed up and copied Novak's QR url! fixed now!

View on HN

Ok, this is getting strange. There are two ways to get test results:

- it's automatically sent to email (if they have it)

- you can download it from ezdravlje.rs portal

The test I shared above is the one I got on email. However, I went to portal, downloaded pdf, and now I have two copies. They're different! IDs and all the data are the same, but QR codes are different.

This is the new one: https://pcr.euprava.gov.rs/validate.php?cqcode=1641923234g3D...

Timestamp on new pdf is: 1641923234, which is GMT: Tuesday, 11. January 2022. 17:47:14

So it appears that timestamp is related to when pdf is generated, and when you download it from the portal it's generated at that point of time, i.e. there are no pdf documents sitting on government server!

So this timestamp is definitely no proof of forgery. But test ID might be - that one is still suspicious.

And one more thing, when I switch tabs with my two QR codes - page content is the same but shifted a bit. I didn't look into html/css to see what's different.

This is super important for everyone to see. The timestamp is not proof of time of test but rather the time that the test was "generated" for download. Anyone prominent on Twitter should respond and assist with this information.

I've done these kinds of systems many times in the past and there could be any amount of reasons why a timestamp is included like this. Especially with weird government regulations, policies and rules that mandate all sorts of info to be included inside government documents. Like adding a year or date to when a company was registered to a company's company registration no.

Nah, let's just run with the story first, could generate a fair amount of clicks!

I've been beating this drum for a while, but HN really needs to just ban direct links to Twitter threads. I can't remember the last time I saw one on the front page that was actually true.

So new policy is to shoot the messenger, then?

When the messenger is spreading false information all the time, yeah, you shouldn't let them be a messenger anymore. I wasn't being hyperbolic: the vast majority of Twitter threads that I've seen make it to the HN frontpage, easily above 75%, are factually incorrect ragebait.

Sucks to be the fourth messenger then. Blanket bans would also block post by amazing Twitter users like foone.

It sounds like you just don’t like or use Twitter. Is that accurate?

No, I go on Twitter multiple times a week and generally like it. Any active Twitter user will tell you that it's common for false and misleading tweets to go viral. That doesn't mean the site is bad, but it does mean it's a bad idea to go around posting random tweets on news aggregators, since there'll always be someone tweeting any take you can think of.

> That doesn't mean the site is bad, but it does mean it's a bad idea to go around posting random tweets on news aggregators, since there'll always be someone tweeting any take you can think of.

We’re not talking about random tweets, we’re talking about on-topic tweets from posters like foone which consistently post relevant content. You’re throwing the good out with the bad and claiming that folks submitting off topic links are bad apples that ruin the whole barrel. I just don’t find your logical argument internally consistent or rational.

Again, what I'm saying is that I don't think there's much good being thrown out. I don't know who foone is, so it's possible I have a biased sample somehow (maybe I don't visit at the right times?) but almost every tweet I've seen linked on HN has been false or misleading.

There have been multiple tweets that reached the front page in the last 24 hours that were quality, substantive, relevant to HN content.

I’ll admit I do use Twitter (and HN!) a lot, though.

Here’s one with 600+ points. You’re telling me we should block Twitter on HN. I’m saying that’s a bad idea for HN. Seems like the users of HN agree with me. HN is for all of us, not just any one user’s preferences.

https://news.ycombinator.com/item?id=29913693

https://twitter.com/TechEmails/status/1481339345822879745

Can you see from your records whether the confirmation number (i.e. 7601263-535518) is fixed at the time of the report, e.g. sent as part of the email? An alternative that comes to my mind is that the number is assigned when the report is first generated, which could in principle explain why Djokovic's numbers are out of order if the first time he accessed his PDF was on 26 Dec.

My two PDFs with different QR codes have the same test ID (7601263-535518). So that one is not generated on the fly. But we don't know 100% if it's generated on database insert (altough it very much looks like that), or if there are some batches depending on lab, PCR batch, etc.

Yup, its timestamp for creation of PDF. Just tested on my old PCR tests and timestamp i get in URL is from 11.1.2022. and PCR swab was done on 27.2.2021.

I have 2 more datapoints. My wife went with me to the testing on the same date. If you're negative on rapid test, they usually take PCR as well. Since she was negative on the first one, there was a PCR too. These are her QR urls:

Rapid test:

https://pcr.euprava.gov.rs/validate.php?cqcode=16415703349MJ...

Timestamp: 1641570334, time: GMT: Friday, 7. January 2022. 15:45:34

PCR:

https://pcr.euprava.gov.rs/validate.php?cqcode=1641924832NyL...

Timestamp: 1641924832, time: GMT: Tuesday, 11. January 2022. 18:13:52

I downloaded PCR from portal today, that's why it has today's timestamp.

What's interesting is that her test IDs are 7601574 and 7631146 while they were taken within 15 minutes from each other. There's some 30k difference, and I think Serbia runs around 40k tests a day. PCR samples are sent to central lab and processed later, that would explain why PCR's ID is much higher.

However I don't think we have definite proof of how these test IDs are generated. Different labs could be assigned batches of IDs, PCR tests itself could have preassigned IDs (you can see they have same ID when you're tested, but I'm not sure it's the same ID as presented in results). If test ID is generated when results are inserted into database, then they should always be incremental and Novak's test IDs point to forgery. But there could be other explanations.

My conclusions:

- timestamps are not proof of forgery

- test IDs are suspicious, but we can't be sure.

Hey, it'd be great if you'd reach out to zerforschung at hallo@zerforschung.org :)

I've sent a brief email with links to these posts. Let's see if they publish a correction!

Great analysis!

Another question: Are all results displayed in green color, also the positiv ones?

All valid reports ("Report is VALID!") - both negative and positive tests - are in green color (Bootstrap 3 class .alert-success).

All invalid reports ("Report IS NOT VALID!") are in red color (Bootstrap 3 class .alert-danger). You can see it when open https://pcr.euprava.gov.rs without any subdir/script/query string.

Thx, for the feedback. In germany it's quite unusual to display the positive test in green, that's why I asked.

Initially, I had the same thought. Greetings from Germany too :-)

Green/red have the same semantics in Serbia as in Germany.

This green for positive test mean just that QR code and associated test are valid, not that it’s good or bad. Positive test is bad in the first 14 days but after that it’s good - it gives you same rights as if you were vaccinated. But it’s the same test in both cases and green just tells us it’s a valid document.

Digital certificate is different kind of document. That’s the one you need to enter restaurans, bars, etc. after 20h - it will be red if you don’t fulfill conditions, e.g. vaccination or positive test within last 6 months (but not within 14 days), etc.

In programer’s lingo, test result is const, while digital certificate is a function of multiple conditions in context of current date/time.

Intro: Looking at covid19.rs/homepage-english/ I can see that there was a total of 1.444.532 people tested and the data is marked for 10.01.2022 at 15:00.

This is exactly the same as here: https://ourworldindata.org/coronavirus/country/serbia

So I'm assuming that this dataset can be trusted.

The point:

From the dataset: Date: 2021-12-16, new tests: 13690.0, total tests: 7032035.0 Date: 2021-12-22, new tests: 14808.0, total tests: 7107851.0 Date: 2021-12-26, new tests: 9265.0, total tests: 7158932.0

As We can see Djoko's "ID" (7371999) is much larger than total number of tests for 26th of December 2021 (by 213067) and for me this furthers your point that We don't know how this number is generated. (It seems to be sequential, but is it?)

They probably generate ID when results are stored in database, not when samples are taken. Difference in processing time explains this. What are the dates of result (stated at the bottom of the pdf)?

The question I have is this - is the test ID generated when the test results are generated for the first time (either sent by email if they have it, or accessed through eGov or eHealth portal), or are they generated as soon as test results are complete? If it's the former, then it's theoretically possible that the first (positive) results have been downloaded for the first time on Dec 26, and thus have a higher ID number.

Unfortunately, no data points from me, even though I have been tested MANY times due to my profession. They've got my email, so they obviously get generated immediately.

However, I do have a data point for screenshots when QR code of the positive test stated that the result was negative. This is something that happened to me as well (back in 2020, once, and never since then). It was a bug, obviously. The second part of the ID is person-specific (all my test results have that second part identical, regardless of when they were taken) - it seems that if a positive test is followed by a negative test, that happens sometimes.

Third option: the test ID is generated well before the test is taken.

When I donate blood the nurse pulls out a sheet of around 20 pre-generated identical barcode stickers, and attaches one to each piece of paper and bag of blood. This uniquely identifies my donation end-to-end.

Djokovic's PCR tests were done at two separate labs. It is quite possible that each lab is bulk-allocated a unique range of IDs every day or week from the central authority. You'd see big "time jumps" from one lab to the other if you assumed the ID was always in time order.

Depending on how they handle their range (e.g. if they are handing physical stacks of barcode stickers around) the code may not even always be in time order in the same lab.

Additionally, on Novak's PCR test from Dec 16th on the website, the test result "NEGATIVE" had been changed to "POSITIVE" sometime around 14h00 on January 10th. Noticed by several people, including myself (took screenshot even myself before and after).

BTW, apparently my IP address has now been blocked accessing to that website :) I get this message now: "Ваша адреса је блокирана 24 сата! Vaša adresa je blokirana 24 sata! Your address is blocked for 24 hours!"

I just got blocked for 24 hours as well. After opening https://pcr.euprava.gov.rs/validate.php?cqcode=1641591150Q!A... just fine -tried to see what happens when you change the digits to cqcode=1641591151... :)

While I guess in these cases governments don't really worry about enumeration aka https://en.wikipedia.org/wiki/German_tank_problem - it's still often a security risk that means you usually try to avoid it.

Even when internally you have auto-incremental ID - you can provide a non-sequential public ID (e.g. at least use SkipJack/Skip32 of that incremental value).

Rate limiting has been implemented on this validation page from the start to prevent crawling and abuse. And please do not lie about changes on the test! Really bad thing to do right now, not just for Novak, for everyone in his situation.

Skipping the part where I discuss my general doubt of intellectual capabilities of the fellow commenters here.

- Datum uzorkovanja (Date of sampling): 22.12.2021 14:12:10

- Datum izdavanja rezultata (Date of issuance of results): 22.12.2021 16:15:49

=> I will ignore the time needed to get the actual swabs to the laboratory and do the necessary paperwork etc and round this to ~2 hours of time available for testing.

- Vrsta analize i proizvodjac testa (Type of analysis and test manufacturer): Real Time PCR test-SARS-CoV-2, , Sansure Biotech INC; Hunan Province

See, unless my fellow countrymen have developed a way to do PCR tests 5 times faster than the fastest tests available in the (rest) of the world, this test in itself is a joke. This is the reason PCR testing: costs, is usually indicated by symptoms already present/positive antigen test.

You're welcome.

Take care

>See, unless my fellow countrymen have developed a way to do PCR tests 5 times faster than the fastest tests available in the (rest) of the world, this test in itself is a joke.

While I have no clue how they work in detail they offer 60 min express PCRs in Germany at least at my airport.

Also these guys in Canada offer 60- and 20-minute PCR tests: https://www.bonvoyagemedical.com/

Those are NAATs, which, while they are based on polymerase chain reaction (PCR), are not the same as PCR reported in the test. Plus, I'm unsure as to where you saw 20 minutes, the shortest I see offered there is 'whithin an hour'.

https://www.medicaldevice-network.com/news/fda-roche-pcr-tes...

Seems to be FDA approved.

Those are NAATs, which, while they are based on polymerase chain reaction (PCR), are not the same as PCR reported in the test.

my company bought a pcr machine for our medical office 45 minut turn around and its not naat but PCR

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