QR Codes Explained

We use QR codes daily for different things like making payments, storing your travel information, visiting websites, connecting to Wi-Fi networks. These barcodes can be captured using smartphones. So in this article let's understand what is a QR code and how do they work.

What is QR Code?
Qr codes were first developed by a subsidiary of Toyota 'Denso Wave' to quickly track vehicles and parts through the company's automotive manufacturing process.QR code stands for Quick Response Code. Although Denso Wave still holds patents over the technology, QR codes are free for anyone to use without a license fee as long as the intellectual property is being used within the defined ISO/JIS standards.QR codes are machine-readable labels — computers can understand them much more easily than they can understand the text.

In 2016 for instance, Snapchat and iMessage introduced support for QR codes as a method of adding new friends, WhatsApp uses QR codes as a quick way to access the desktop version of their chat application, and Android recently introduced similar functionality for sending SMS and MMS text messages on the PC.

How do they work?
As with any other barcode, interacting with a QR code is simple enough: scan one with an image sensor such as the camera in your smartphone, the app you're using will convert the code to binary and then display the information or perform the programmed action, such as opening a website, essentially allowing real-world objects to be hyperlinked to digital places.

A QR code is comprised of an array of squares, some of which are used for the image sensor to position itself (that's the large squares on three of the corners), while the rest of the cells contain version and format information as well as the data itself, of course, along with error correction coding.

Whereas most of the barcodes you come across are one-dimensional, such as labels on items at the store, QR codes are two-dimensional and offer many advantages. For instance, QR codes can be scanned in any direction instead of only one, they can contain thousands of alphanumeric characters versus only a dozen or so, and when configured with a high level of error correction they are particularly capable at continuing to function after sustaining damage. The more error correction a QR code has, the less data it can store, and incidentally, the more data that is stored within a QR code, the more squares it will have. More squares are also required as the level of error correction is increased and artistic QR codes can forego data capacity for aesthetics by creating an image with some of the blocks.

An early version of the two-dimensional barcode system measured only 21 x 21 modules and contained just four characters of data, while the largest current version (40) spans 177 x 177 modules and can hold 1,264 characters of ASCII text or up to up to 7,089 numerals. Information can be encoded by a variety of methods and different types of encoding can be used in the same QR code:

• Numeric (10 bits per 3 digits)
• Alphanumeric (11 bits per 2 characters, but can't store lowercase letters)
• Byte (8 bits per character)
• Kanji (13 bits per character)
• And some more obscure modes such as FNC1 and ECI

Along with different standards for conventional QR codes, specifications for new iterations have been approved over the years, including MicroQR (11×11 modules containing as many as 35 numeric characters), iQR Code (holds 80% more data in the same space as a standard QR code), FrameQR (the one lets you create images in the QR code) and SQRC (stores public and private data, the latter of which can only be read by certain scanners).

While generally speaking QR codes are deemed safe to use, their most common exploit uses the URL data type to redirect users to malicious websites, for phishing purposes or by hosting executable data that exploits vulnerabilities in the client's applications (reader, web browser or image viewer).

There have been other incidents where malware has infected Android phones, for example, to send costly SMS or to steal bank account information without the user ever noticing.

Image credits:- Techspot