QR codes: more than just a COVID thing – Tech News | Particle – Particle

The short answer: nothing unexpected but its a fascinating look at how code and coders store data and why transparency matters.

QR codes have been around for decades. They were originally invented at Toyota to help label car parts on production lines, but theyve worked their way into everyday life as well. From putting links on a bus stop ad to tracing contacts during a pandemic, storing a little bit of computer data on paper is a useful thing to be able to do.

But how do these strange little squares actually work? And what kind of data are they hiding? To find out, we talked to James Hentsridge, an open-source software developer. James wrote an amazing technical breakdown of whats in WAs very own SafeWA check-in codes.

So this is kind of like barcodes on your food, except its designed so that it can store a lot more data, James says.

Data is still stored as a pattern of black and white spaces, but rather than lines read from left to right, its squares dotted from right to left, bottom to top, snaking back and forth across a grid.

And rather than just a sequence of numbers, it can be arbitrary text data or even binary, James says.

That means QR codes can store code, images, words, or as well see web addresses. Because theyre storing more data, theyve got a few extra tricks up their sleeve to make sure that data survives.

Its also designed with some error correction, so that if theres a smudge on your camera lens or someones put a logo in the centre of the QR code, it can still recover all the data.

Its a bit like the check digit on a regular barcode or a credit card number, but instead of just being able to verify the data, it can actually help fix it as well.

What caught Jamess eye about the SafeWA codes was their size. While theyre the same type of codes as, say, our Particle posters, the SafeWA codes have a lot more dots.

Theres two things that can increase the size of the QR code. One of them is, yes, more data means bigger QR codes, he says.

The other one is you can change the redundancy. You could have very little redundancy, which means any errors in the scanning will mean you lose data, or lots of redundancy means it will increase the size of the code but you can fix more errors.

SafeWA codes are either storing a lot of data or using a lot of error correction, but to figure out which it is, we need to go deeper.

Fortunately, the SafeWA app isnt the only bit of software that can read these codes. Since its a standard QR code, we can open it in a different app one that shows us exactly whats being encoded.

And what do we see? Its a web address, or URL, but thats not exactly surprising, according to James.

Theres a good reason to have this as a URL, because it identifies this as a SafeWA QR code rather than something else, he says. After that, youve got a big long string of letters and numbers, he says.

That means if you scan it with your camera app say, if youre new to WA and dont have the app yet you get sent to a website with more details rather than seeing just those letters and numbers. To a regular camera app, they dont mean much, but to the SafeWA app, its the name and location of the venue youve visited.

The SafeWA app sees that this URL is structured in a certain way, and then it extracts this venue ID and location, and it talks to the server and says you were here.

The codes are big because that web address comes out pretty long perhaps longer than it needs to be. It turns out theyve got a little bit of redundancy and error correction in there as well, which James says could easily be left off to make the code a bit smaller.

So despite the layers and layers of coding, SafeWA codes really do seem to be exactly what they claim to be. Its your check-in location wrapped up in a way thats easy for a phone to understand. But its important for humans to be able to understand it too.

All these check-in systems depend on consent of people to actually participate. So if you break that trust, then theyre worthless, James says.

Part of that trust is transparency. Its easier to trust a system if you know how it works and that it does what it says. James says thats something anyone can try.

Trying to investigate these sorts of things a lot of it is just looking for patterns, he says.

This article was originally published on Particle. Read the original article.

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QR codes: more than just a COVID thing - Tech News | Particle - Particle