A QR code (abbreviated from Quick Response code) is a type of matrix barcode (or two-dimensional code) first designed for the automotive industry. More recently, the system has become popular outside of the industry due to its fast readability and comparatively large storage capacity. The code consists of black modules arranged in a square pattern on a white background. The information encoded can be made up of any kind of data (e.g., binary, alphanumeric, or Kanji symbols).
Created by Toyota subsidiary Denso Wave in 1994 to track vehicles during the manufacturing process, the QR code is one of the most popular types of two-dimensional barcodes. It was designed to allow its contents to be decoded at high speed.
The technology has seen frequent use in Japan; the United Kingdom is the seventh-largest national consumer of QR codes.
Standards
Structure of a QR code, highlighting functional elements
There are several standards in documents covering the physical encoding of QR codes:
§ October 1997 — AIM (Association for Automatic Identification and Mobility) Internationa
§ January 1999 — JIS X 0510
§ June 2000 — ISO/IEC 18004:2000 Information technology — Automatic identification and data capture techniques — Bar code symbology — QR code (now withdrawn)
Defines QR code models 1 and 2 symbols.
§ September 1, 2006 — ISO/IEC 18004:2006 Information technology — Automatic identification and data capture techniques — QR code 2005 bar code symbology specification
Defines QR code 2005 symbols, an extension of QR code model 2. Does not specify how to read QR code model 1 symbols, or require this for compliance.
At the application layer, there is some variation between implementations. NTT DoCoMo has established de facto standards for the encoding of URLs, contact information, and several other data types.[7] The open-source "ZXing" project maintains a list of QR code data types.
Design
Storage
The amount of data that can be stored in the QR code depends on the character set, version and error correction level. The maximum values for version 40 with error correction capacity level L:
| Numeric only | Max. 7,089 characters |
| Alphanumeric | Max. 4,296 characters |
| Binary (8 bits) | Max. 2,953 bytes |
| Kanji/Kana | Max. 1,817 characters |
§ 
Version 1, 21x21, 10-25 alphanumeric chars
§ 
Version 2, 25x25, 20-47 alphanumeric chars
§ 
Version 3, 29x29, 35-77 alphanumeric chars
§ 
Version 4, 33x33, 50-114 alphanumeric chars
§ 
Version 10, 57x57, 174-395 alphanumeric chars
§ 
Version 40, 177x177, 1,852-4,296 alphanumeric chars
Encoding
The diagram below illustrates the placement of the message characters within a QR code. Starting from the lower-right corner, the first four bits define the encoding used (in this case, 8 bits per character). Next is the length of the message (17; dark stands for 1, but the masking process used in this symbol inverts alternate rows). Following that is the message itself, then the end-of-message marker, and finally the error-correcting codes.
Encryption
Although encrypted QR codes are not very common, there are a few implementations. An Android app,[10] for example, manages encryption and decryption of QR codes using a secure AES 128 algorithm.[11] Japanese immigration use encrypted QR codes when placing visas in passports.
Error correction
Example of a QR code with artistic embellishment that will still scan correctly thanks to error correction.
Codewords are 8 bits long and use the Reed–Solomon error correction algorithm with four error correction levels. The higher the error correction level, the less storage capacity. While the exact number of errors that can be corrected depends on the size of the symbol and the location of the errors, the following table lists the approximate error correction capability at each of the four levels:
| Level L | 7% of codewords can be restored. |
| Level M | 15% of codewords can be restored. |
| Level Q | 25% of codewords can be restored. |
| Level H | 30% of codewords can be restored. |
At the highest error correction level it is possible to create artistic QR codes that still scan correctly, but contain intentional errors to make them more readable or attractive to the human eye, as well as to incorporate colors, logos and other features into the QR code block.
License
The use of QR codes is free of any license. The QR code is clearly defined and published as an ISO standard. Denso Wave owns thepatent rights on QR codes, but has chosen not to exercise them.
In the USA, the granted QR code patent is US 5726435. In Japan it is JP 2938338. In Germany it is DE 69518098 (the European Patent Office granted patent EP0672994 to Denso Wave, but Denso only "nationalized" the patent grant in Germany).
The term QR code itself is a registered trademark of Denso Wave Incorporated.[14]
Variants
Example ofMicro QR
Micro QR code is a smaller version of the QR code standard for applications with less ability to handle large scans. There are different forms of Micro QR codes as well. The highest of these can hold 35 numeric characters.
Standard QR code is the QR code standard for applications that possess the ability to handle large scans. A standard QR code can contain up to 7089 characters, though not all QR readers can accept that much data.
Uses
Although initially used to track parts in vehicle manufacturing, QR codes are now (as of 2011) used over a much wider range of applications, including commercial tracking, entertainment and transport ticketing, product marketing and in-store product labeling. Many of these applications target mobile-phone users (via mobile tagging). Users may receive text, add a vCard contact to their device, open a Uniform Resource Identifier (URI), or compose an e-mail or text message after scanning QR codes. They can generate and print their own QR codes for others to scan and use by visiting one of several pay or free QR code-generating sites or apps. Google has a popular API to generate QR codes, and apps for scanning QR codes can be found on nearly all smartphone devices.
QR codes storing addresses and Uniform Resource Locators (URLs) may appear in magazines, on signs, on buses, on business cards, or on almost any object about which users might need information. Users with a camera phone equipped with the correct reader application can scan the image of the QR code to display text, contact information, connect to a wireless network, or open a web page in the telephone's browser. This act of linking from physical world objects is termed hard linking or object hyper linking.
QR codes can be used in Google's mobile Android operating system via both their own Google Goggles application or 3rd party barcode scanners like ZXing or Kaywa. The browser supports URI redirection, which allows QR codes to send metadata to existing applications on the device. Nokia's Symbian operating system features a barcode scanner which can read QR codes, while barcode is a QR code reader for the Maemo operating system. In the Apple iOS, a QR code reader is not natively included, but more than fifty paid and free apps are available with both scanning capabilities and hard-linking to URI. With BlackBerry devices, the App World application can natively scan QR codes and load any recognized Web URLs on the device's Web browser. Windows Phone 7.5 is able to scan QR codes through the Bing search app.
In the USA, QR code usage is expanding.[citation needed] During the month of June 2011, according to one study, 14 million mobile users scanned a QR code or a barcode. Some 58% of those users scanned a QR or bar code from their home, while 39% scanned from retail stores; 53% of the 14 million users were men between the ages of 18 and 34.
While the adoption of QR codes in some markets has been slow to begin (particularly in markets such as the United States, where competing standards such as Data Matrix exist), the technology is gaining some traction in the smartphone market. Many Android, Nokia, Blackberry handsets, and the Nintendo 3DS, come with QR code readers installed. QR reader software is available for most mobile platforms. Moreover, there are a number of online QR code generators which enable users to create QR codes for their own needs.
Risks
Malicious QR codes combined with a permissive reader can put a computer's contents and user's privacy at risk. QR codes intentionally obscure and compress their contents and intent to humans. They are easily created and may be affixed over legitimate QR codes.]On a smartphone, the reader's many permissions may allow use of the camera, full internet access, read/write contact data, GPS, read browser history, read/write local storage, and global system changes.
Risks include linking to dangerous websites with browser exploits, enabling the microphone/camera/GPS and then streaming those feeds to a remote server, exfiltrating sensitive data (passwords, files, contacts, transactions), and sending email/SMS/IM messages or DDOSpackets as part of a botnet, corrupting privacy settings, stealing identity, and even containing malicious logic themselves such as JavaScript or a virus. These actions may occur in the background while the user only sees the reader opening a harmless webpage.
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