Quick response code (QR)

A QR code, or Quick Response code, is a type of two-dimensional barcode that can be read using smartphones and other devices.

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A QR code, or Quick Response code, is a type of two-dimensional barcode that can be read using smartphones and dedicated QR reading devices, which link directly to text, emails, websites, phone numbers and more. This technology has become popular due to its fast readability and greater storage capacity compared to standard UPC barcodes.

Developed by Denso Wave in 1994, QR codes are now used in a wide array of applications, including commercial tracking, product and time tracking, document management, and general marketing. In the context of cybersecurity, QR codes can be both a tool for secure communication and a potential vulnerability to be exploited by malicious actors.

How QR codes work

QR codes work similarly to traditional barcodes, which are a familiar sight on product packaging in stores. However, instead of storing data in a series of vertical lines, QR codes do so in a grid of tiny squares. This allows them to hold much more information.

The data in a QR code is stored in both a vertical and a horizontal direction, hence the term ""2D."" This is in contrast to barcodes, which only store data in one direction. This is why QR codes can hold hundreds of times more data than a barcode.

Encoding and decoding

When a QR code is created, the data is encoded into a pattern of black and white squares. This pattern can then be read by a QR code scanner, which decodes the pattern and presents the data in a readable form. The encoding and decoding process is what allows QR codes to hold a variety of data types, from simple text to links to websites.

The encoding process is complex and involves error correction codes, which ensure that the QR code can still be read even if it is somewhat damaged or obscured. This makes QR codes a reliable form of data storage and transmission.

Scanning QR codes

Scanning a QR code is a simple process. All that is needed is a device with a camera and a QR code reader application. Most smartphones today come with built-in QR code readers in their camera apps. Once the QR code is scanned, the data is instantly displayed on the device.

Some QR codes, especially those used for payments or sensitive information, may require additional steps after scanning, such as entering a password or confirming a transaction. This adds an extra layer of security to the process.

QR Codes and cybersecurity

In the realm of cybersecurity, QR codes present both opportunities and challenges. On one hand, they can be used to enhance security measures and streamline authentication processes. On the other hand, they can also be used by cybercriminals to carry out attacks.

QR codes can be used to store sensitive information securely. For example, they can be used to store encrypted passwords or keys for secure communication. They can also be used in two-factor authentication, where a user must scan a QR code in addition to entering a password to gain access to a system.

QR code attacks

Despite their potential for enhancing security, QR codes can also be exploited by cybercriminals. One common method is through QR code substitution, where a legitimate QR code is replaced with a malicious one. When scanned, the malicious QR code could direct the user to a phishing site or download malware onto their device.

Another method is through QR code overlay, where a transparent sticker with a malicious QR code is placed over a legitimate one. This can be particularly dangerous as the malicious QR code may be difficult to detect visually.

Preventing QR code attacks

There are several measures that can be taken to prevent QR code attacks. One is to always verify the source of a QR code before scanning it. If the source is unknown or suspicious, it's best not to scan the code.

Another measure is to use a QR code scanner that has security features, such as checking the decoded URL against a database of known malicious URLs. Some scanners also provide a preview of the URL before opening it, allowing the user to verify that it is safe.

Future of QR codes in cybersecurity

As technology continues to evolve, so too will the use of QR codes in cybersecurity. One potential area of growth is in the use of dynamic QR codes, which can change over time. This could be used to provide an additional layer of security for sensitive information.

Another potential area of growth is in the integration of QR codes with other technologies, such as blockchain and artificial intelligence. This could open up new possibilities for secure communication and authentication.

Dynamic QR codes

Dynamic QR codes are a type of QR code that can change over time. This can be used to provide an additional layer of security, as the data stored in the QR code can be updated or changed as needed. For example, a dynamic QR code could be used to generate a new password for each login attempt.

Dynamic QR codes could also be used to provide real-time updates or notifications. For example, a QR code on a product could be updated to provide the latest information about the product, such as price changes or recalls.

Integration with other technologies

QR codes can also be integrated with other technologies to enhance their security capabilities. For example, they can be used in conjunction with blockchain technology to create a secure, tamper-proof record of transactions. This could be particularly useful in industries such as supply chain management and finance.

Similarly, QR codes can be integrated with artificial intelligence to create more sophisticated security solutions. For example, AI could be used to analyze the patterns in a QR code and detect any anomalies that could indicate a security threat.


QR codes are a versatile technology with a wide range of applications, including in the field of cybersecurity. While they can be used to enhance security measures, they can also be exploited by cybercriminals. As such, it's important to understand how QR codes work and how they can be used securely.

As technology continues to evolve, we can expect to see new and innovative uses for QR codes in cybersecurity. Whether it's through the use of dynamic QR codes or the integration with other technologies, the future of QR codes in cybersecurity looks promising.

This post has been updated on 17-11-2023 by Sofie Meyer.

Author Sofie Meyer

About the author

Sofie Meyer is a copywriter and phishing aficionado here at Moxso. She has a master´s degree in Danish and a great interest in cybercrime, which resulted in a master thesis project on phishing.

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