QR code

From HandWiki
Short description: Type of matrix barcode
QR code for the URL of the English Wikipedia Mobile main page

A QR code (Quick Response code) is a type of two-dimensional matrix barcode, invented in 1994, by Japanese company Denso Wave for labelling automobile parts.[1][2] A barcode is a machine-readable optical image that contains information specific to the labelled item. In practice, QR codes contain data for a locator, an identifier, and a website visitor tracking. To efficiently store data, QR codes use four standardized modes of encoding (i) numeric, (ii) alphanumeric, (iii) byte or binary, and (iv) kanji.[3]

A QR code consists of black squares arranged in a square grid on a white background, including some fiducial markers, which can be read by an imaging device such as a camera, and processed using Reed–Solomon error correction until the image can be appropriately interpreted. The required data is then extracted from patterns that are present in both horizontal and vertical components of the image.[4]

The QR labelling system was applied beyond the automobile industry due to its fast readability and greater storage capacity compared to standard UPC barcodes. Applications include product tracking, item identification, time tracking, document management, and general marketing.[4]


The QR code system was invented in 1994 under a team led by Masahiro Hara from the Japanese company Denso Wave.[5][6][7] The initial design was influenced by the black and white pieces on a Go board,[8] the position detection pattern was found using the least used ratio in black and white areas on printed matter can avoid misidentifying, which was 1:1:3:1:1.[9][5] Its purpose was to keep track of automotive parts manufactured by Denso, to replace several bar codes on each box, each of which had to be scanned separately, with the requirement of high capacity that is able to encode Kanji, Kana and alphanumerics together.[10][9][5]


A QR code being painted on the side of a building
QR codes can be displayed on buildings, such as this one being painted in Cape Town.

QR codes are now[when?] used in a much broader context, including both commercial tracking applications and convenience-oriented applications aimed at mobile-phone users (termed mobile tagging). QR codes may be used to display text to the user, to open a webpage on the user's device, to add a vCard contact to the user's device, to open a Uniform Resource Identifier (URI), to connect to a wireless network, or to compose an email or text message. There are a great many QR code generators available as software or as online tools that are either free, or require a paid subscription.[11] The QR code has become one of the most-used types of two-dimensional code.[12]

During the month of June 2011, 14 million American mobile users scanned a QR code or a barcode. Some 58% of those users scanned a QR or barcode from their homes, while 39% scanned from retail stores; 53% of the 14 million users were men between the ages of 18 and 34.[13]

In September 2020, a survey found that 18.8 percent of consumers in the United States and United Kingdom strongly agreed that they had noticed an increase of QR code use since the then-active COVID-19 related restrictions had begun several months prior.[14]


Structure of a QR code (version 7), highlighting functional elements

There are several standards that cover the encoding of data as QR codes:[15]

  • October 1997 – AIM (Association for Automatic Identification and Mobility) International[16]
  • 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.
  • 1 September 2006 – ISO/IEC 18004:2006 Information technology – Automatic identification and data capture techniques – QR Code 2005 bar code symbology specification (now withdrawn)[17]
    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.
  • 1 February 2015 – ISO/IEC 18004:2015 Information – Automatic identification and data capture techniques – QR Code barcode symbology specification
    Renames the QR Code 2005 symbol to QR Code and adds clarification to some procedures and minor corrections.
  • May 2022 – ISO/IEC 23941:2022 Information technology – Automatic identification and data capture techniques – Rectangular Micro QR Code (rMQR) bar code symbology specification[18]
    Defines the requirements for Micro QR Code.

At the application layer, there is some variation between most of the implementations. Japan's NTT DoCoMo has established de facto standards for the encoding of URLs, contact information, and several other data types.[19] The open-source "ZXing" project maintains a list of QR code data types.[20]


A QR code used on a large billboard in Japan, linking to the sagasou.mobi website

QR codes have become common in consumer advertising. Typically, a smartphone is used as a QR code scanner, displaying the code and converting it to some useful form (such as a standard URL for a website, thereby obviating the need for a user to type it into a web browser). QR code has become a focus of advertising strategy, since it provides a way to access a brand's website more quickly than by manually entering a URL.[21][22] Beyond mere convenience to the consumer, the importance of this capability is that it increases the conversion rate: the chance that contact with the advertisement will convert to a sale. It coaxes interested prospects further down the conversion funnel with little delay or effort, bringing the viewer to the advertiser's website immediately, whereas a longer and more targeted sales pitch may lose the viewer's interest.

Although initially used to track parts in vehicle manufacturing,[citation needed] QR codes are used over a much wider range of applications. These include commercial tracking, warehouse stock control, entertainment and transport ticketing, product and loyalty marketing and in-store product labeling.[citation needed] Examples of marketing include where a company's discounted and percent discount can be captured using a QR code decoder that is a mobile app, or storing a company's information such as address and related information alongside its alpha-numeric text data as can be seen in Yellow Pages directories.[citation needed]

They can also be used in storing personal information for use by organizations. An example of this is Philippines National Bureau of Investigation (NBI) where NBI clearances now come with a QR code. Many of these applications target mobile-phone users (via mobile tagging). Users may receive text, add a vCard contact to their device, open a URL, 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 had an API, now deprecated, to generate QR codes,[23] and apps for scanning QR codes can be found on nearly all smartphone devices.[24]

QR codes have been used and printed on train tickets in China since 2010.[25]

QR codes storing addresses and URLs may appear in magazines, on signs, on buses, on business cards, or on almost any object about which users might want 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 phone's browser. This act of linking from physical world objects is termed hardlinking or object hyperlinking. QR codes also may be linked to a location to track where a code has been scanned. Either the application that scans the QR code retrieves the geo information by using GPS and cell tower triangulation (aGPS) or the URL encoded in the QR code itself is associated with a location. In 2008, a Japanese stonemason announced plans to engrave QR codes on gravestones, allowing visitors to view information about the deceased, and family members to keep track of visits.[26] Psychologist Richard Wiseman was one of the first authors to include QR codes in a book, in Paranormality: Why We See What Isn't There (2011).[27][failed verification] Microsoft Office and LibreOffice have a functionality to insert QR code into documents.[28][29]

QR codes have been incorporated into currency. In June 2011, The Royal Dutch Mint (Koninklijke Nederlandse Munt) issued the world's first official coin with a QR code to celebrate the centenary of its current building and premises. The coin can be scanned by a smartphone and originally linked to a special website with contents about the historical event and design of the coin.[30] In 2014, the Central Bank of Nigeria issued a 100-naira banknote to commemorate its centennial, the first banknote to incorporate a QR code in its design. When scanned with an internet-enabled mobile device, the code goes to a website that tells the centenary story of Nigeria.[31] In 2015, the Central Bank of the Russian Federation issued a 100-rubles note to commemorate the annexation of Crimea by the Russian Federation. It contains a QR code into its design, and when scanned with an internet-enabled mobile device, the code goes to a website that details the historical and technical background of the commemorative note. In 2017, the Bank of Ghana issued a 5-cedis banknote to commemorate 60 years of Central Banking in Ghana, and contains a QR code in its design, which when scanned with an internet-enabled mobile device, that code goes to the official Bank of Ghana website.

Credit card functionality is under development. In September 2016, the Reserve Bank of India (RBI) launched the eponymously named Bharat QR, a common QR code jointly developed by all the four major card payment companies – National Payments Corporation of India that runs RuPay cards along with MasterCard, Visa and American Express. It will also have the capability of accepting payments on the unified payments interface (UPI) platform.[32][33]

Augmented reality

QR codes are used in some augmented reality systems to determine the positions of objects in 3-dimensional space.[10]

Displaying multimedia contents

QR codes also used to direct users to specific multimedia content (such as videos, audios, images, documents and any type of content accessible from the web). This type of QR code is called "Multimedia QR code".

Mobile operating systems

QR codes can be used on various mobile device operating systems. iPhones running on iOS 11 and higher[34] and some Android devices can natively scan QR codes without downloading an external app.[35] The camera app is able to scan and display the kind of QR code (only on iPhone) along with the link (both on Android and iPhone). These devices support URL redirection, which allows QR codes to send metadata to existing applications on the device. Many paid or free apps are available with the ability to scan the codes and hard-link to an external URL.

Virtual stores

QR codes have been used to establish "virtual stores", where a gallery of product information and QR codes is presented to the customer, e.g. on a train station wall. The customers scan the QR codes, and the products are delivered to their homes. This use started in South Korea,[36] and Argentina,[37] but is currently expanding globally.[38] Walmart, Procter & Gamble and Woolworths have already adopted the Virtual Store concept.[39]

QR code payment

Main page: Finance:QR code payment

QR codes can be used to store bank account information or credit card information, or they can be specifically designed to work with particular payment provider applications. There are several trial applications of QR code payments across the world.[40][41] In developing countries like China,[42][43] India[44] and Bangladesh QR code payment is a very popular and convenient method of making payments. Since Alipay designed a QR code payment method in 2011,[45] mobile payment has been quickly adopted in China. As of 2018, around 83% of all payments were made via mobile payment.[46]

In November 2012, QR code payments were deployed on a larger scale in the Czech Republic when an open format for payment information exchange – a Short Payment Descriptor – was introduced and endorsed by the Czech Banking Association as the official local solution for QR payments.[47][48] In 2013, the European Payment Council provided guidelines for the EPC QR code enabling SCT initiation within the Eurozone.

In 2017, Singapore created a taskforce including their Government Agencies such as the Monetary Authority of Singapore and Infocomm Media Development Authority to spearhead a system for e-payments using standardized QR code specifications. These specific dimensions are specialized for Singapore’s market.[49]

The e-payment system, Singapore Quick Response Code (SGQR), essentially merges various QR codes into one label that can be used by both parties in the payment system. This allows for various banking apps to facilitate payments between multiple customers and a merchant that displays the single QR code.[50]

A single SDQR label contains e-payments and combines multiple payment options. Once consumers spot the SGQR label, they will be able to scan it and see which payment options the merchant accepts. The SGQR scheme is co-owned by MAS and IMDA.[51]

Website login

QR codes can be used to log into websites: a QR code is shown on the login page on a computer screen, and when a registered user scans it with a verified smartphone, they will automatically be logged in. Authentication is performed by the smartphone, which contacts the server. Google tested such a login method in January 2012.[52]

Mobile ticket

There is a system whereby a QR code can be displayed on a device such as a smartphone and used as an admission ticket.[53][54][55] Its use is common for J1 League and Nippon Professional Baseball tickets in Japan.[56][57] In some cases, rights can be transferred via the Internet.

A sign with a QR code that links to a drinks menu

Restaurant ordering

Restaurants can present a QR code near the front door or at the table allowing guests to view an online menu, or even redirect them to an online ordering website or app, allowing them to order and/or possibly pay for their meal without having to use a cashier or waiter. QR codes can also link to daily or weekly specials that are not printed on the standardized menus,[58] and enable the establishment to update the entire menu without needing to print copies. At table-serve restaurants, QR codes enable guests to order and pay for their meals without a waiter involved – the QR code contains the table number so servers know where to bring the food.[59][60] This application has grown especially since the need for social distancing during the 2020 COVID-19 pandemic prompted reduced contact between service staff and customers.[59]

Joining a Wi‑Fi network

A QR code to automatically join a Wi‑Fi network

By specifying the SSID, encryption type, password/passphrase, and if the SSID is hidden or not, mobile device users can quickly scan and join networks without having to manually enter the data.[61] A MeCard-like format is supported by Android and iOS 11+.[62]

  • Common format: WIFI:S:<SSID>;T:<WEP|WPA|blank>;P:<PASSWORD>;H:<true|false|blank>;;
  • Sample: WIFI:S:MySSID;T:WPA;P:MyPassW0rd;;

Funerary use

A QR code that links to an obituary and can be placed on a headstone

A QR code can link to an obituary and can be placed on a headstone. In 2008, Ishinokoe in Yamanashi Prefecture, Japan began to sell tombstones with QR codes produced by IT DeSign, where the code leads to a virtual grave site of the deceased.[63][64][65] Other companies, such as Wisconsin-based Interactive Headstones, have also begun implementing QR codes into tombstones.[66] In 2014, the Jewish Cemetery of La Paz in Uruguay began implementing QR codes for tombstones.[67]

Electronic authentication

QR codes are also used to generate time-based one-time passwords (TOTP) for electronic authentication.

Loyalty programs

QR codes have been used by various retail outlets that have loyalty programs. Sometimes these programs are accessed with an app that is loaded onto a phone and includes a process triggered by a QR code scan. The QR codes for loyalty programs tend to be found printed on the receipt for a purchase or on the products themselves. Users in these schemes collect award points by scanning a code.

Counterfeit detection

Serialised QR codes have been used by brands[68] and governments[69] to let consumers, retailers and distributors verify the authenticity of the products and help with detecting counterfeit products, as part of a brand protection program.[70] However, the security level of a regular QR code is limited since QR codes printed on original products are easily reproduced on fake products, even though the analysis of data generated as a result of QR code scanning can be used to detect counterfeiting and illicit activity.[71] A higher security level can be attained by embedding a digital watermark or copy detection pattern into the image of the QR code. This makes the QR code more secure against counterfeiting attempts, and fake products that contain a counterfeit QR code can be detected by scanning the secure QR code with a specific app (even though the QR code message itself is valid).[72]

The treaty regulating apostilles (documents bearing a seal of authenticity), has been updated to allow for the issuance of digital apostilles by countries; a digital apostille is a PDF document with a cryptographic signature containing a QR code for a canonical URL of the original document, allowing users to verify the apostille from a printed version of the document.

Product tracing

Different studies have been made to assess the effectiveness of QR codes as a means of conveying labelling information and their use as part of a food traceability system. In a field experiment, it was found that when provided free access to a smartphone with QR code scanning app, 52.6% of participants would use it to access labelling information.[73] A study made in South Korea showed that consumers appreciate QR code used in food traceability system, as they provide detailed information about food, as well as information that helps them in their purchasing decision.[74] If QR codes are serialised, consumers can access a web page showing the supply chain for each ingredient, as well as information specific to each related batch, including meat processors and manufacturers, which helps address the concerns they have about the origin of their food.[75]

COVID-19 pandemic

Two QR codes that link to German contact tracing app check-ins during the COVID-19 pandemic

After the COVID-19 pandemic began spreading, QR codes began to be used as a "touchless" system to display information, show menus, or provide updated consumer information, especially in the hospitality industry. Restaurants replaced paper or laminated plastic menus with QR code decals on the table, which opened an online version of the menu. This prevented the need to dispose of single-use paper menus, or institute cleaning and sanitizing procedures for permanent menus after each use.[76] Local television stations have also begun to utilize codes on local newscasts to allow viewers quicker access to stories or information involving the pandemic, including testing and immunization scheduling websites, or for links within stories mentioned in the newscasts overall.

In several Australian states, patrons are required to scan QR codes at shops, clubs, supermarkets and other service and retail establishments on entry to assist contact tracing. Singapore, Taiwan, the United Kingdom and New Zealand use similar systems.[77]

QR codes are also present on COVID-19 vaccination certificates in places such as Canada, and the EU (EU Digital COVID certificate) where they can be scanned to verify the information on the certificate.[78]


Unlike the older, one-dimensional barcodes that were designed to be mechanically scanned by a narrow beam of light, a QR code is detected by a 2-dimensional digital image sensor and then digitally analyzed by a programmed processor. The processor locates the three distinctive squares at the corners of the QR code image, using a smaller square (or multiple squares) near the fourth corner to normalize the image for size, orientation, and angle of viewing. The small dots throughout the QR code are then converted to binary numbers and validated with an error-correcting algorithm.

Information capacity

The amount of data that can be represented by a QR code symbol depends on the data type (mode, or input character set), version (1, ..., 40, indicating the overall dimensions of the symbol, i.e. 4 × version number + 17 dots on each side), and error correction level. The maximum storage capacities occur for version 40 and error correction level L (low), denoted by 40-L:[12][79]

Maximum character storage capacity (40-L)
Character refers to individual values of the input mode (data type).
Input mode Max. characters Bits/char. Possible characters, default encoding
Numeric only 7,089 3​13 0, 1, 2, 3, 4, 5, 6, 7, 8, 9
Alphanumeric 4,296 5​12 0–9, A–Z (upper-case only), space, $, %, *, +, -, ., /, :
Binary/byte 2,953 8 ISO/IEC 8859-1
Kanji/kana 1,817 13 Shift JIS X 0208

Here are some samples of QR codes:

Error correction

Damaged but still decodable QR code, link to http://en.m.wikipedia.org
Example of a QR code with artistic embellishment that will still scan correctly thanks to error correction

QR codes use Reed–Solomon error correction over the finite field [math]\displaystyle{ \mathbb{F}_{256} }[/math], the elements of which are encoded as bytes of 8 bits; the byte [math]\displaystyle{ b_7b_6b_5b_4b_3b_2b_1b_0 }[/math] with a standard numerical value [math]\displaystyle{ \textstyle\sum_{i=0}^7 b_i 2^i }[/math] encodes the field element [math]\displaystyle{ \textstyle\sum_{i=0}^7 b_i \alpha^i }[/math] where [math]\displaystyle{ \alpha \in \mathbb{F}_{256} }[/math] is taken to be a primitive element satisfying [math]\displaystyle{ \alpha^8 + \alpha^4 + \alpha^3 + \alpha^2 + 1 = 0 }[/math]. The primitive polynomial is [math]\displaystyle{ x^8 + x^4 + x^3 + x^2 + 1 }[/math], corresponding to the polynomial number 285, with initial root = 0. The Reed–Solomon code uses one of 37 different polynomials over [math]\displaystyle{ \mathbb{F}_{256} }[/math], with degrees ranging from 7 to 68, depending on how many error correction bytes the code adds. It is implied by the form of Reed–Solomon used (systematic BCH view) that these polynomials are all on the form [math]\displaystyle{ \prod_{i=0}^{n-1} (x - \alpha^i) }[/math], however the rules for selecting the degree [math]\displaystyle{ n }[/math] are specific to the QR standard.

When discussing the Reed–Solomon code phase there is some risk for confusion, in that the QR ISO/IEC standard uses the term codeword for the elements of [math]\displaystyle{ \mathbb{F}_{256} }[/math], which with respect to the Reed–Solomon code are symbols, whereas it uses the term block for what with respect to the Reed–Solomon code are the codewords. The number of data versus error correction bytes within each block depends on (i) the version (side length) of the QR symbol and (ii) the error correction level, of which there are four. The higher the error correction level, the less storage capacity. The following table lists the approximate error correction capability at each of the four levels:

Level L (Low) 7% of data bytes can be restored.
Level M (Medium) 15% of data bytes can be restored.
Level Q (Quartile)[80] 25% of data bytes can be restored.
Level H (High) 30% of data bytes can be restored.

In larger QR symbols, the message is broken up into several Reed–Solomon code blocks. The block size is chosen so that no attempt is made at correcting more than 15 errors per block; this limits the complexity of the decoding algorithm. The code blocks are then interleaved together, making it less likely that localized damage to a QR symbol will overwhelm the capacity of any single block.

Due to error correction, it is possible to create artistic QR codes with embellishments to make them more readable or attractive to the human eye, and to incorporate colors, logos, and other features into the QR code block; the embellishments are treated as errors, but the codes still scan correctly.[81][82]

It is also possible to design artistic QR codes without reducing the error correction capacity by manipulating the underlying mathematical constructs.[83][84] Image processing algorithms are also used to reduce errors in QR-code.[85]


The format information records two things: the error correction level and the mask pattern used for the symbol. Masking is used to break up patterns in the data area that might confuse a scanner, such as large blank areas or misleading features that look like the locator marks. The mask patterns are defined on a grid that is repeated as necessary to cover the whole symbol. Modules corresponding to the dark areas of the mask are inverted. The format information is protected from errors with a BCH code, and two complete copies are included in each QR symbol.[4]

The message dataset is placed from right to left in a zigzag pattern, as shown below. In larger symbols, this is complicated by the presence of the alignment patterns and the use of multiple interleaved error-correction blocks.

The general structure of a QR encoding is as a sequence of 4 bit indicators with payload length dependent on the indicator mode (e.g. byte encoding payload length is dependent on the first byte).[86]

Mode indicator Description Typical structure '[ type : sizes in bits ]'
0001 Numeric [0001 : 4] [ Character Count Indicator : variable ] [ Data Bit Stream : 3​13 × charcount ]
0010 Alphanumeric [0010 : 4] [ Character Count Indicator : variable ] [ Data Bit Stream : 5​12 × charcount ]
0100 Byte encoding [0100 : 4] [ Character Count Indicator : variable ] [ Data Bit Stream : 8 × charcount ]
1000 Kanji encoding [1000 : 4] [ Character Count Indicator : variable ] [ Data Bit Stream : 13 × charcount ]
0011 Structured append [0011 : 4] [ Symbol Position : 4 ] [ Total Symbols: 4 ] [ Parity : 8 ]
0111 ECI [0111 : 4] [ ECI Assignment number : variable ]
0101 FNC1 in first position [0101 : 4] [ Numeric/Alphanumeric/Byte/Kanji payload : variable ]
1001 FNC1 in second position [1001 : 4] [ Application Indicator : 8 ] [ Numeric/Alphanumeric/Byte/Kanji payload : variable ]
0000 End of message [0000 : 4]
  • Character Count Indicator depends on how many modules are in a QR code (Symbol Version).
  • ECI Assignment number Size:
    • 8 × 1 bits if ECI Assignment Bitstream starts with '0'
    • 8 × 2 bits if ECI Assignment Bitstream starts with '10'
    • 8 × 3 bits if ECI Assignment Bitstream starts with '110'

Four-bit indicators are used to select the encoding mode and convey other information.

Encoding modes
Indicator Meaning
0001 Numeric encoding (10 bits per 3 digits)
0010 Alphanumeric encoding (11 bits per 2 characters)
0100 Byte encoding (8 bits per character)
1000 Kanji encoding (13 bits per character)
0011 Structured append (used to split a message across multiple QR symbols)
0111 Extended Channel Interpretation (select alternate character set or encoding)
0101 FNC1 in first position (see Code 128 for more information)
1001 FNC1 in second position
0000 End of message (Terminator)

Encoding modes can be mixed as needed within a QR symbol. (e.g., a url with a long string of alphanumeric characters )

[ Mode Indicator][ Mode bitstream ] --> [ Mode Indicator][ Mode bitstream ] --> etc... --> [ 0000 End of message (Terminator) ]

After every indicator that selects an encoding mode is a length field that tells how many characters are encoded in that mode. The number of bits in the length field depends on the encoding and the symbol version.

Number of bits in a length field (Character Count Indicator)
Encoding Ver. 1–9 10–26 27–40
Numeric 10 12 14
Alphanumeric 9 11 13
Byte 8 16 16
Kanji 8 10 12

Alphanumeric encoding mode stores a message more compactly than the byte mode can, but cannot store lower-case letters and has only a limited selection of punctuation marks, which are sufficient for rudimentary web addresses. Two characters are coded in an 11-bit value by this formula:

V = 45 × C1 + C2

This has the exception that the last character in an alphanumeric string with an odd length is read as a 6-bit value instead.

Alphanumeric character codes
Code Character Code Character Code Character Code Character Code Character
00 0 09 9 18 I 27 R 36 Space
01 1 10 A 19 J 28 S 37 $
02 2 11 B 20 K 29 T 38 %
03 3 12 C 21 L 30 U 39 *
04 4 13 D 22 M 31 V 40 +
05 5 14 E 23 N 32 W 41
06 6 15 F 24 O 33 X 42 .
07 7 16 G 25 P 34 Y 43 /
08 8 17 H 26 Q 35 Z 44 :

Decoding example

The following images offer more information about the QR code.


Model 1

Model 1 QR code is an older version of the specification. It is visually similar to the widely seen model 2 codes, but lacks alignment patterns. Differences are in the bottom right corner, and in the midsections of the bottom and right edges are additional functional regions.

Micro QR code

Micro QR code is a smaller version of the QR code standard for applications where symbol size is limited. There are four different versions (sizes) of Micro QR codes: the smallest is 11×11 modules; the largest can hold 35 numeric characters.[87]

IQR code

IQR code is an alternative to existing QR codes developed by Denso Wave. IQR codes can be created in square or rectangular formations; this is intended for situations where a rectangular barcode would otherwise be more appropriate, such as cylindrical objects. IQR codes can fit the same amount of information in 30% less space. There are 61 versions of square IQR codes, and 15 versions of rectangular codes. For squares, the minimum size is 9 × 9 modules; rectangles have a minimum of 19 × 5 modules. IQR codes add error correction level S, which allows for 50% error correction.[88] IQR Codes have not yet been given an ISO/IEC specification, and only proprietary Denso Wave products can create or read IQR codes.[89]

Secure QR code

Secure Quick Response (SQR) code is a QR code that contains a "private data" segment after the terminator instead of the specified filler bytes "ec 11".[90] This private data segment must be deciphered with an encryption key. This can be used to store private information and to manage company's internal information.[91]

SQR codes have been developed by the FORUS Foundation to enable secure transactions, and published under a Creative Commons Licence. The SQR solution guarantees the integrity of the source data as well as the validity of the originating party. The payment instruction string is made up of the electronic instruction data from the scanned QR code appended with a SHA-2 cryptographic hash. The message digest can then be encrypted using the private key of the sender, which then creates a digital signature of the message. This signature validates the integrity of the data and the trustworthiness of the sender. This provides non-repudiation, confirming the identity of the sender, and that it has not been tampered with during transmission. By embedding the URL and all the variables required to perform shopping cart type e-commerce, bill payment and peer to peer payments, coupled with a digital certificate eliminates the possibility of spoofing, tampering, and man-in-the-middle attacks. [92]

Frame QR

Frame QR is a QR code with a "canvas area" that can be flexibly used. In the center of this code is the canvas area, where graphics, letters, and more can be flexibly arranged, making it possible to lay out the code without losing the design of illustrations, photos, etc.[93]


Samples of the High Capacity Colored 2-Dimensional (HCC2D) code: (a) 4-color HCC2D code and (b) 8-color HCC2D code.

Researchers have proposed a new High Capacity Colored 2-Dimensional (HCC2D) Code, which builds upon a QR code basis for preserving the QR robustness to distortions and uses colors for increasing data density (as of 2014 it is still in prototyping phase). The HCC2D code specification is described in details in Querini et al. (2014),[94] while techniques for color classification of HCC2D code cells are described in detail in Querini and Italiano (2014),[95] which is an extended version of Querini and Italiano (2013).[96]

Introducing colors into QR codes requires addressing additional issues. In particular, during QR code reading only the brightness information is taken into account, while HCC2D codes have to cope with chromatic distortions during the decoding phase. In order to ensure adaptation to chromatic distortions that arise in each scanned code, HCC2D codes make use of an additional field: the Color Palette Pattern. This is because color cells of a Color Palette Pattern are supposed to be distorted in the same way as color cells of the Encoding Region. Replicated color palettes are used for training machine learning classifiers.


The use of QR code technology is freely licensed as long as users follow the standards for QR code documented with JIS or ISO/IEC. Non-standardized codes may require special licensing.[97]

Denso Wave owns a number of patents on QR code technology, but has chosen to exercise them in a limited fashion.[97] In order to promote widespread usage of the technology Denso Wave chose to waive its rights to a key patent in its possession for standardized codes only.[15] In the US, the granted QR code patent is US patent 5726435, and in Japan JP patent 2938338, both of which have expired. The European Patent Office granted patent EP patent 0672994 to Denso Wave, which was then validated into French, UK, and German patents, all of which expired in March 2015.[98]

The text QR Code itself is a registered trademark and wordmark of Denso Wave Incorporated.[99] In UK, the trademark is registered as E921775, the term QR Code, with a filing date of 3 September 1998.[100] The UK version of the trademark is based on the Kabushiki Kaisha Denso (DENSO CORPORATION) trademark, filed as Trademark 000921775, the term QR Code, on 3 September 1998 and registered on 16 December 1999 with the European Union OHIM (Office for Harmonization in the Internal Market).[101] The U.S. Trademark for the term QR Code is Trademark 2435991 and was filed on 29 September 1998 with an amended registration date of 13 March 2001, assigned to Denso Corporation.[102]


The only context in which common QR codes can carry executable data is the URL data type. These URLs may host JavaScript code, which can be used to exploit vulnerabilities in applications on the host system, such as the reader, the web browser or the image viewer, since a reader will typically send the data to the application associated with the data type used by the QR code.

In the case of no software exploits, malicious QR codes combined with a permissive reader can still put a computer's contents and user's privacy at risk. This practice is known as "attagging", a portmanteau of "attack tagging".[103] They are easily created and can be affixed over legitimate QR codes.[104] On a smartphone, the reader's 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.[105][106][107]

Risks include linking to dangerous web sites with browser exploits, enabling the microphone/camera/GPS, and then streaming those feeds to a remote server, analysis of sensitive data (passwords, files, contacts, transactions),[108] and sending email/SMS/IM messages or packets for DDoS as part of a botnet, corrupting privacy settings, stealing identity,[109] and even containing malicious logic themselves such as JavaScript[110] or a virus.[111][112] These actions could occur in the background while the user is only seeing the reader opening a seemingly harmless web page.[113] In Russia, a malicious QR code caused phones that scanned it to send premium texts at a fee of United States dollar 6 each.[103] QR codes have also been linked to scams in which stickers are placed on parking meters, posing as quick payment options, as seen in Austin, San Antonio and Boston, among other cities across the United States and Australia.[114][115][116]

See also


  1. Hung, Shih-Hsuan; Yao, Chih-Yuan; Fang, Yu-Jen; Tan, Ping; Lee, RuenRone; Sheffer, Alla; Chu, Hung-Kuo (2020-09-01). "Micrography QR Codes". IEEE Transactions on Visualization and Computer Graphics 26 (9): 2834–2847. doi:10.1109/TVCG.2019.2896895. ISSN 1077-2626. PMID 30716038. https://ieeexplore.ieee.org/document/8632711. Retrieved 21 April 2021. 
  2. Chen, Rongjun; Yu, Yongxing; Xu, Xiansheng; Wang, Leijun; Zhao, Huimin; Tan, Hong-Zhou (2019-12-11). "Adaptive Binarization of QR Code Images for Fast Automatic Sorting in Warehouse Systems" (in en). Sensors 19 (24): 5466. doi:10.3390/s19245466. PMID 31835866. Bibcode2019Senso..19.5466C. 
  3. "QR Code features". Denso-Wave. http://www.qrcode.com/en/qrfeature.html. 
  4. 4.0 4.1 4.2 "QR Code Essentials". Denso ADC. 2011. http://www.nacs.org/LinkClick.aspx?fileticket=D1FpVAvvJuo%3D&tabid=1426&mid=4802. 
  5. 5.0 5.1 5.2 "QRコード開発|テクノロジー|デンソーウェーブ" (in ja). https://www.denso-wave.com/ja/technology/vol1.html. 
  6. "2D Barcodes". NHK World-Japan. 2020-03-26. https://www3.nhk.or.jp/nhkworld/en/ondemand/video/2072031/. 
  7. "From Japanese auto parts to ubiquity: A look at the history of QR codes" (in en). Mainichi Daily News. 2021-11-09. https://mainichi.jp/english/articles/20211109/p2a/00m/0bu/024000c. 
  8. "The Little-Known Story of the Birth of the QR Code". 2020-02-10. https://www.nippon.com/en/news/fnn20191214001/the-little-known-story-of-the-birth-of-the-qr-code.html. 
  9. 9.0 9.1 "History of QR Code". https://www.qrcode.com/en/history/. 
  10. 10.0 10.1 Borko Furht (2011). Handbook of Augmented Reality. Springer. p. 341. ISBN 9781461400646. https://books.google.com/books?id=fG8JUdrScsYC&q=Handbook%20of%20Augmented%20Reality&pg=PA341. 
  11. Joe Waters. "How to Use the Top QR Code Generators". http://www.dummies.com/business/marketing/social-media-marketing/how-to-use-the-top-qr-code-generators/. 
  12. 12.0 12.1 "QR Code—About 2D Code". Denso-Wave. http://www.qrcode.com/en/about/. 
  13. "14m Americans scanned QR and bar codes with their mobiles in June 2011". 16 August 2011. http://www.internetretailing.net/2011/08/14m-americans-scanned-qr-and-bar-codes-with-their-mobiles-in-june-2011/. 
  14. "U.S. and UK increase of QR code use 2020". 6 July 2021. https://www.statista.com/statistics/199328/qr-code-scanners-by-age/. 
  15. 15.0 15.1 "QR Code Standardization". QR Code.com. Denso-Wave. http://www.qrcode.com/en/about/standards.html. 
  16. "ISS QR Code|AIM Store: Historical Archive". Aimglobal.org. https://aimglobal.site-ym.com/store/ViewProduct.aspx?id=2590968. 
  17. "ISO/IEC 18004:2006 - Information technology  – Automatic identification and data capture techniques  – QR Code 2005 bar code symbology specification" (in en). https://www.iso.org/standard/43655.html. 
  18. "ISO/IEC 23941:2022 Information technology — Automatic identification and data capture techniques — Rectangular Micro QR Code (rMQR) bar code symbology specification". ISO. https://www.iso.org/standard/77404.html. 
  19. "Synchronization with Native Applications". NTT DoCoMo. https://www.nttdocomo.co.jp/english/service/developer/make/content/barcode/function/application/index.html. 
  20. Sean Owen (17 January 2014). "Barcode contents". https://github.com/zxing/zxing/wiki/Barcode-Contents. 
  21. Rimma Kats (23 January 2012). "Starbucks promotes coffee blend via QR codes". http://www.mobilemarketer.com/cms/news/software-technology/11930.html. 
  22. Jenny Lee (4 January 2012). "Tesco's cool QR code advertising campaign". https://vancouversun.com/news/staff-blogs/tescos-cool-qr-code-advertising-campaign. 
  23. "Getting Started with Infographics (deprecated)". 26 May 2015. https://google-developers.appspot.com/chart/infographics/docs/overview. 
  24. "QR Code Readers for iPhone, Android, Blackberry and Windows Phone 7". 2010-12-07. http://www.708media.com/qrcode/qr-code-readers-iphone-android-blackberry-windows-phone-7/. 
  25. "QR codes on China's train tickets may leak personal information". Want China Times. http://www.wantchinatimes.com/news-subclass-cnt.aspx?id=20121216000074&cid=1103. 
  26. Novak, Asami (2008-03-23). "Japanese Gravestones Memorialize the Dead With QR Codes". Wired. https://www.wired.com/underwire/2008/03/japanese-graves/. 
  27. Skepticality (5 July 2011). "Paranormality". Skepticality.com. http://www.skepticality.com/paranormality/. 
  28. "Field codes: DisplayBarcode". https://support.microsoft.com/en-us/office/field-codes-displaybarcode-6d81eade-762d-4b44-ae81-f9d3d9e07be3. 
  29. "LibreOffice 6.4: Release Notes". https://wiki.documentfoundation.org/ReleaseNotes/6.4. 
  30. "Herdenkingsmunt met QR code volop in het nieuws!" (in nl). 21 June 2011. http://www.knm.nl/Herdenkingsmunt-met-QR-code-volop-in-het-nieuws/nl/news/206/?NieuwsGroepID=1&NWSY=2011&NWSM=6. 
  31. "New ₦100 Commemorative Centenary Celebration". http://sites.visualead.me/ngp_new/. 
  32. www.ETRetail.com. "With IndiaQR launch, retail payments to get digital edge - ET Retail" (in en). http://retail.economictimes.indiatimes.com/news/e-commerce/e-tailing/with-indiaqr-launch-retail-payments-to-get-digital-edge/57158555. 
  33. "IndiaQR to debut on Feb 20". The Times of India. http://timesofindia.indiatimes.com/business/india-business/indiaqr-to-debut-on-feb-20/articleshow/57154107.cms. 
  34. Hein, Buster (2017-09-21). "How to scan QR codes with iOS 11's Camera app". https://www.cultofmac.com/485380/how-to-scan-qr-codes-iphone/. 
  35. Lacoma, Tyler (2018-10-03). "How to Scan a QR Code". https://www.digitaltrends.com/mobile/how-to-scan-a-qr-code/. 
  36. "Tesco QR Code Virtual Store". 14 April 2012. http://www.shop2mobi.com/blog/tesco-qr-code-virtual-store/. 
  37. Sebastián Campanario (16 September 2011). "Marketing futurista: ya se puede comprar con la cámara del celular" (in es). http://www.ieco.clarin.com/empresas/Marketing-futurista-comprar-camara-celular_0_555544518.html. 
  38. "Marketers scatter phone-friendly codes across ads". 11 November 2010. http://www.physorg.com/news/2010-11-phone-friendly-codes-ads.html. 
  39. "Top 10 QR Code Store examples". 14 April 2012. http://www.shop2mobi.com/blog/virtual-qr-code-store-examples/. 
  40. "SCVNGR Unveils QR Code Payment System". 12 October 2011. http://mashable.com/2011/10/12/scvngr-levelup-redo/. 
  41. "MasterCard starts piloting QkR mobile payment app". 2012-01-26. http://gigaom.com/2012/01/26/mastercard-starts-piloting-qkr-mobile-payment-app/. 
  42. Jacobs, Harrison. "One photo shows that China is already in a cashless future". https://www.businessinsider.com/alipay-wechat-pay-china-mobile-payments-street-vendors-musicians-2018-5. 
  43. Mozur, Paul (2017-07-16). "In Urban China, Cash Is Rapidly Becoming Obsolete" (in en-US). The New York Times. ISSN 0362-4331. https://www.nytimes.com/2017/07/16/business/china-cash-smartphone-payments.html. 
  44. "Paying With Your Mobile Wallet To Get Simpler With Interoperable QR Codes". https://www.moneycontrol.com/news/business/personal-finance/paying-with-your-mobile-wallet-to-get-simpler-with-interoperable-qr-codes-6026991.html. 
  45. "A Hangzhou Story: The Development of China's Mobile Payment Revolution". https://lkyspp.nus.edu.sg/docs/default-source/case-studies/a-hangzhou-story.pdf?sfvrsn=2bb6690a_2. 
  46. "Payment methods in China: How China became a mobile-first nation". https://daxueconsulting.com/payment-methods-in-china/. 
  47. "Standard - Formát pro sdílení platebních údajů v rámci tuzemského platebního styku v CZK prostřednictvím QR kódů" (in cs). Czech Banking Association. November 2012. https://www.czech-ba.cz/aktivity/standardy/format-pro-sdileni-platebnich-udaju-v-czk-qr-kody. 
  48. "Formát pro sdílení platebních údajů v CZK - QR kódy" (in cs). the Czech Banking Association. August 2015. https://cbaonline.cz/format-pro-sdileni-platebnich-udaju-v-czk-qr-kody. 
  49. IMDA (November 9, 2022). "Annex A – Fact sheet on Singapore Quick Response Code (SGQR)". https://www.imda.gov.sg/-/media/Imda/Files/About/Media-Releases/2018/Annex-A--Singapore-Quick-Response-Code-SGQR.pdf. 
  50. Monetary Authority of Singapore (November 9, 2022). "Singapore Quick Response Code (SGQR)". https://www.mas.gov.sg/development/e-payments/sgqr. 
  51. Monetary Authority of Singapore (November 9, 2022). "Singapore Quick Response Code (SGQR)". https://www.mas.gov.sg/development/e-payments/sgqr. 
  52. "Google testing login authentication via QR codes". http://www.zdnet.com/blog/security/google-testing-login-authentication-via-qr-codes/10105. 
  53. "Mobile ticket generation|applications|QR Code Solutions|system solutions|DENSO WAVE" (in en). https://www.denso-wave.com/en/system/qr/katsuyou/index2.html. 
  54. "【公式】チケットの使い方 東京ディズニーリゾート" (in ja). https://www.tokyodisneyresort.jp/ticket/usage.html. 
  55. "ダイレクトイン(QRコード)の使い方|USJ WEBチケットストア" (in ja). https://www.usj.co.jp/ticket/guide/use.html. 
  56. "QRチケットレス入場について" (in ja). https://www.sanfrecce.co.jp/tickets/qrcode. 
  57. "スマートスタジアム" (in ja). https://www.rakuteneagles.jp/special/qrticket/. 
  58. Management 2020 (https://modernrestaurantmanagement.com),+Modern Restaurant (2020-10-22). "Restaurant QR Codes: 2020's Comeback Story | Restaurant QR Codes: 2020's Comeback Story | Modern Restaurant Management | The Business of Eating & Restaurant Management News" (in en-US). https://modernrestaurantmanagement.com/restaurant-qr-codes-2020s-comeback-story/. 
  59. 59.0 59.1 Kastrenakes, Jacob (September 29, 2020). "Square launches QR codes that let you order from your table at a restaurant". VOX Media LLC.. https://www.theverge.com/2020/9/29/21456594/square-qr-code-order-restaurants-pandemic-menu. 
  60. Glass, Noah (October 7, 2020). "How To Prepare For Table Service 2.0". https://www.forbes.com/sites/forbestechcouncil/2020/10/07/how-to-prepare-for-table-service-20/?sh=61a7e804271b. 
  61. "Share your Wi-Fi SSID & Password using a QR Code". 2015-07-19. http://www.technostarry.com/share-wi-fi-details-using-qr-code/. 
  62. "zxing documentation: barcode contents" (in en). zxing. https://github.com/zxing/zxing/wiki/Barcode-Contents. 
  63. "モノウォッチは生まれ変わります". http://www.j-cast.com/mono/2008/03/20018046.html. 
  64. Michael Keferl (20 March 2008). "QR code graves give a "Memorial Window"". Japan Trends. http://www.japantrends.com/qr-code-graves-give-a-memorial-window/. 
  65. "供養の窓 - 石の声 株式会社" (in ja). http://mobile.ishinokoe.co.jp/. 
  66. "Quiring Monuments adds smartphone codes to gravestones". Puget Sound Business Journal. 26 April 2011. http://www.bizjournals.com/seattle/blog/2011/04/seattle-company-quiring-monuments-adds.html. 
  67. "Uruguayan Jewish Cemetery QR-ified" (in es). EL PAIS. 24 March 2014. http://www.elpais.com.uy/informacion/cementerio-judio-se-moderniza-codigos.html. 
  68. "Exclusive - CHINA: Pernod Ricard to use QR codes on all China packaging". 2013-09-17. https://www.just-drinks.com/news/pernod-ricard-to-use-qr-codes-on-all-china-packaging_id111521.aspx. 
  69. "Digital tax stamps will curb fake goods - URA" (in en). https://www.monitor.co.ug/Business/Technology/Digital-tax-stamps-will-curb-fake-goods-URA--/688612-5462046-h6c29h/index.html. 
  70. "The power of smart packaging" (in en). https://www.bakingbusiness.com/articles/49373-the-power-of-smart-packaging?v=preview. 
  71. Baldini, Gianmarco; Nai Fovino, Igor; Satta, Riccardo; Tsois, Aris; Checchi, Enrico (2015). Survey of techniques for the fight against counterfeit goods and Intellectual Property Rights (IPR) infringement.. Luxembourg: European Commission. Joint Research Centre, Publications Office. ISBN 978-92-79-54543-6. OCLC 948769705. 
  72. Carron, Cecilia (2015-05-06). "Combatting counterfeiting using QR codes" (in en). https://phys.org/news/2015-05-combatting-counterfeiting-qr-codes.html. 
  73. Li, Tongzhe; Messer, Kent D.; Li, Tongzhe; Messer, Kent D. (2019). Li, Tongzhe; Messer, Kent D.. eds. "To Scan or Not to Scan: The Question of Consumer Behavior and QR Codes on Food Packages". Journal of Agricultural and Resource Economics. doi:10.22004/ag.econ.287977. ISSN 1068-5502. https://ageconsearch.umn.edu/record/287977/. Retrieved 24 June 2020. 
  74. Kim, Yeong Gug; Woo, Eunju (2016-07-01). "Consumer acceptance of a quick response (QR) code for the food traceability system: Application of an extended technology acceptance model (TAM)" (in en). Food Research International 85: 266–272. doi:10.1016/j.foodres.2016.05.002. ISSN 0963-9969. PMID 29544844. http://www.sciencedirect.com/science/article/pii/S0963996916301880. 
  75. "Behind Every Smart Product is Smart Packaging | Future Food Asia". https://futurefoodasia.com/2019/11/smartpackaging/. 
  76. Leger, Benjamin (2020-10-27). "QR codes are replacing physical menus at restaurants" (in en). https://www.225batonrouge.com/food-drink/qr-codes-replacing-physical-menus-restaurants. 
  77. Purtill, James (19 November 2020). "The proliferation of QR code check-ins is a 'dog's breakfast'. Is there a better way?" (in en-AU). www.abc.net.au (Australian Broadcasting Corporation). https://www.abc.net.au/news/science/2020-11-20/covid-19-coronavirus-why-so-many-qr-code-check-in-systems/12895678. 
  78. Hristova, Bobby (2021-12-28). "Ontarians need QR code to prove vaccination next week. Here's what you need to know" (in en-CA). https://www.cbc.ca/news/canada/hamilton/qr-code-hamilton-covid-19-1.6299207. 
  79. "Information capacity and versions of QR Code". Denso-Wave. http://www.qrcode.com/en/about/version.html. 
  80. "2D Barcode: QR-Code". http://www.tec-it.com/de/support/knowbase/symbologies/qrcode/Default.aspx.  — TEC-IT
  81. Hajra Shannon (18 October 2010). "Form Meets Function: Functionality and Form of QR Codes". https://washingtonindependent.com/functionality-and-form-of-qr-codes/. 
  82. Hamilton Chan (18 April 2011). "HOW TO: Make Your QR Codes More Beautiful". http://mashable.com/2011/04/18/qr-code-design-tips/. 
  83. Russ Cox (12 April 2012). "QArt Codes: How to make pictures with QR codes, part II". http://research.swtch.com/qart. 
  84. Russ Cox (12 April 2012). "QArt Coder". http://research.swtch.com/qr/draw. 
  85. Gupta, Kishor Datta; Ahsan, Md Manjurul; Andrei, Stefan (January 2018). "Extending the Storage Capacity And Noise Reduction of a Faster QR-Code". Brain Broad Research in Artificial Intelligence and Neuroscience 9 (1): 59–71. https://www.researchgate.net/publication/323676167. 
  86. ISO/IEC 18004:2006(E) § 6.4 Data encoding; Table 3 – Number of bits in character count indicator for QR code 2005
  87. Information technology – Automatic identification and data capture techniques – QR Code 2005 bar code symbology specification, ISO/IEC 18004:2006 cor. 2009, pages 3, 6.
  88. "QR Code Overview & Progress of QR Code Applications". http://www.gs1jp.org/pdf/001.pdf#34. 
  89. "iQR Code – QRcode.com – DENSO WAVE". http://www.qrcode.com/en/codes/iqr.html. 
  90. "Embedding Secret Data in QR Code". https://fukuchi.org/works/qrhack/qrhack1.html. 
  91. "SQRC". http://www.qrcode.com/en/codes/sqrc.html. 
  92. "FORUS". https://www.forus.co.za/s-qr/. 
  93. "Frame QR". http://www.qrcode.com/en/codes/frameqr.html. 
  94. "2D Color Barcodes for Mobile Phones". http://www.tmrfindia.org/ijcsa/v8i19.pdf. 
  95. "Reliability and data density in high capacity color barcodes". http://www.doiserbia.nb.rs/img/doi/1820-0214/2014/1820-02141400054Q.pdf. 
  96. "Color classifiers for 2D color barcodes". 2013. https://fedcsis.org/proceedings/2013/pliks/67.pdf. 
  97. 97.0 97.1 "About the patent". Denso-Wave. http://www.qrcode.com/en/patent.html. 
  98. "DPA". https://register.dpma.de/DPMAregister/pat/register?lang=en&AKZ=E951035112. "INPI". http://bases-brevets.inpi.fr/en/document-en/EP0672994.html. "UK IPO". 2013-03-09. https://www.ipo.gov.uk/p-ipsum/Case/PublicationNumber/EP0672994. 
  99. "QR Code.com". Denso-Wave. 6 November 2003. http://www.qrcode.com/en/index.html. 
  100. "UK QR Code Trademark". http://www.ipo.gov.uk/types/tm/t-os/t-find/t-find-number?detailsrequested=C&trademark=E921775. 
  101. "EU QR Code Trademark". http://esearch.oami.europa.eu/copla/trademark/data/000921775. 
  102. "US QR Code Trademark". http://tess2.uspto.gov/bin/showfield?f=doc&state=4010:nrb6eh.2.6. 
  103. 103.0 103.1 "Jargon Watch", Wired 20 (1): 22, January 2012 .
  104. "Malicious Images: What's a QR Code". SANS Technology Institute. 3 August 2011. http://isc.sans.edu/diary.html?storyid=11305. 
  105. "Barcode Scanner". 1 June 2011. https://market.android.com/details?id=com.google.zxing.client.android. 
  106. "QR Droid". 19 August 2011. https://market.android.com/details?id=la.droid.qr. 
  107. "ScanLife Barcode Reader". 24 May 2011. https://market.android.com/details?id=com.ScanLife. 
  108. "Consumer Alert: QR Code Safety". Better Business Bureau. 23 June 2011. http://sandiego.bbb.org/article/consumer-alert-qr-code-safety-28037. 
  109. "AVG Cautions: Beware of Malicious QR Codes". PC World. 28 June 2011. http://www.pcworld.idg.com.au/mediareleases/12655/avg-aunz-cautions-beware-of-malicious-qr-codes/. 
  110. "EvilQR – When QRCode goes bad". AppSec-Labs Blog. 14 August 2011. https://appsec-labs.com/blog/tag/qrcode. 
  111. "QR Codes: A Recipe for a Mobile Malware Tsunami". Cyveillance, Inc. 20 October 2010. http://www.cyveillanceblog.com/malware/qr-codes-a-recipe-for-a-mobile-malware-tsunami. 
  112. QR codes hold up to 2.9 KB whereas the smallest known computer virus is about one-tenth that size "The Smallest Virus I Could Manage". Virus Labs and Distribution. 1995. http://www.wiw.org/~meta/vlad.php?read=ARTICLE.5_2&issue=3&desc=Small%20Virus. 
  113. "Beware of Malicious QR Codes". ABC. 8 June 2011. http://www.abc.net.au/technology/articles/2011/06/08/3238443.htm. 
  114. Binder, Matt. "Beware the QR code scams". https://mashable.com/article/beware-qr-code-scams. 
  115. Vincent, James (12 January 2022). "The latest phishing scam to watch out for: fraudulent QR codes on parking meters". https://www.theverge.com/2022/1/12/22879728/phishing-scam-parking-meter-qr-code-austin-san-antonio. 
  116. Wodinsky, Shoshana (12 January 2022). "Scammers Are Using QR Codes to Plunder Parking Meter Payments". https://gizmodo.com/scammers-are-using-qr-codes-to-plunder-parking-meter-pa-1848347940. 


External links

  • Reed Solomon Codes for Coders – an elaborate tutorial on Wikiversity, covering both QR code structure and the Reed Solomon codes used to encode the data.