2024-09-11 05:54:03
Although pretty much everyone has used a QR code at some point, very few people know how it actually works. We’ll explain.
QR codes are extremely popular these days. The small square bit patterns can be read with any smartphone and make it easier to access websites and exchange information, among other things. But how does a QR code actually work and what makes it so special? The answer is here.
The abbreviation QR stands for Quick Response. The term already makes the intended use clear: QR codes contain information that can be retrieved quickly and easily using a QR code scanner. Today, this can be done with any smartphone using an appropriate app that reads the code using a camera.
The QR code works like a type of barcode, where the information it contains is distributed across two dimensions. This has the advantage that more data can be stored than with a one-dimensional barcode. Up to 7089 decimal digits or 4296 alphanumeric characters can be stored in a QR code.
The type of information stored is determined by the creator of the respective QR code. Basically, any character string can be stored. QR codes are often used to store links to websites and embed them on a poster or flyer, for example. Sometimes, however, QR codes simply contain sequences of numbers that are required for certain processes – for example in the form of package or transaction numbers.
The data in the QR code appears in the form of a bit pattern with a square arrangement. QR codes usually have black and white pixels, each of which represents individual bits of data. But there are also colored versions.
Certain areas in the corners are identical for every QR code and ensure that the scanner correctly recognizes the position and orientation and reads the individual data bits in the correct order. Software then decodes the bit pattern and outputs the character sequence encoded in it, for example a web address. The user can then read this and process it further as desired.
In addition to the actual payload data, the QR code also contains data that serves to ensure error tolerance. If the scanner reads certain bits incorrectly, for example due to contamination, the software can correct this to a certain extent using this additional error data. Depending on the level of error correction, it is possible to restore up to 30 percent of damaged data.
QR codes can be read using various apps. On modern smartphones, this is often possible using the regular camera app. Alternatively, you can also scan with Google Lens or any QR code scanner app, which can be found in large numbers in the Google Play Store and the Apple App Store.
However, caution is advised when scanning QR codes from unknown sources. Especially in public places, QR codes from criminals that embed links to phishing sites occasionally appear. If you do not know the source of a QR code, you should therefore avoid scanning it. Otherwise, there is a risk that an attacker will try to use it to install malware and steal sensitive data from your smartphone.