What Happens When You Scan a Banknote With a QR Code Reader
Japanese Banknotes Have No QR Codes Printed on Them
To get straight to the point, no QR codes are printed on Japanese banknotes (Bank of Japan notes). The new banknotes issued in 2024 (the 10,000-yen note featuring Eiichi Shibusawa, the 5,000-yen note featuring Umeko Tsuda, and the 1,000-yen note featuring Shibasaburo Kitasato) did not adopt QR codes either.
The anti-counterfeiting technologies used on banknotes include holograms, watermarks, microprinting, special inks (whose color changes with the viewing angle), and intaglio printing (which feels raised to the touch). QR codes have not been adopted as an anti-counterfeiting technology.
Several reasons can be considered. Because anyone can easily generate a QR code, it is hard for one to serve an anti-counterfeiting role. In addition, reading a QR code requires a smartphone, and limiting the authentication of banknotes to "people who own a smartphone" is not realistic.
Banknotes With Printed QR Codes Do Exist
Japanese banknotes have no QR codes, but if you look around the world, banknotes with printed QR codes really do exist.
The world's first example is Nigeria. On November 12, 2014, the Central Bank of Nigeria issued a 100-naira note commemorating 100 years since the country's formation as a nation. A QR code was printed on the back, and at the time of issue, scanning it gave access to a site introducing the history of Nigeria. It is a QR code serving as "a gateway to commemorative content," not as anti-counterfeiting for the note itself.
However, this approach has a weakness specific to banknotes. What the QR code points to is a website outside the note, and once that site stops being run, scanning it shows nothing. Because banknotes circulate for many years, only the QR code on the note loses its meaning first. Space on the face of a note is also limited, and placing a QR code means competing for space with the elements meant to prevent counterfeiting. These circumstances are behind why banknotes with QR codes stayed limited to commemorative issues and did not spread to notes in everyday circulation.
QR Readers Do Not React, but Copiers Do
If you point a QR code reader at a banknote, nothing happens. A reading app searches the screen for the square finder patterns in three corners and an arrangement of black and white cells. Because those patterns are not printed on banknotes, the app simply decides there is nothing to read and keeps waiting. No error or warning appears.
With a mechanism other than QR codes, however, machines clearly react to banknotes. When you try to copy a banknote with a copier or scanner, the process may stop partway or a warning message may appear.
One such mechanism is a special pattern printed on banknotes called the "EURion constellation." Small circles are printed repeatedly in a specific arrangement, and when a color copier or scanner detects this arrangement, it stops operating to prevent the banknote from being reproduced.
When you try to open an image of a banknote in Adobe Photoshop, a notice saying it cannot be opened may appear. However, this is not detection of the EURion pattern. It is said that a counterfeit deterrence system (CDS), designed by an organization jointly established by central banks around the world, is built in and detects digital watermarks embedded in banknotes. Experiments have confirmed that images with the EURion pattern removed are still detected, so the two are separate mechanisms.
In other words, banknotes carry two layers of invisible markers meant for machines: a pattern aimed at copiers and digital watermarks aimed at image editing software. They share with QR codes the point of having machines read information that human eyes cannot see, but while a QR code is a gateway that passes information to people, these are markers for stopping reproduction. Even though both are machine-readable, their roles are exact opposites.
Could QR Codes Appear on Japanese Banknotes in the Future?
As cashless payment spreads, the role of banknotes itself is changing. Is there a chance that QR codes will be printed on Japanese banknotes in the future?
One conceivable possibility is a purpose of "providing information" rather than preventing counterfeiting. For example, scanning a QR code could display a detailed biography and the achievements of the person in the portrait on a new banknote. Scanning the 10,000-yen note featuring Eiichi Shibusawa would show his life and his contributions to the Japanese economy. The idea is for banknotes to become "moving textbooks."
However, the hurdles to making this happen are not low. The main purpose of a banknote redesign is to update anti-counterfeiting technology, and a QR code for providing information does not directly connect to that motive. Even if one were added, the site it refers to could stop being run before the banknote does (the same problem as Nigeria's commemorative note). Furthermore, banknotes must be equally usable by everyone, and making information that only people with a reading device can receive part of the face of a note conflicts with that requirement. Even if there is room for QR codes on banknotes, they would likely remain in a supporting position rather than replacing anti-counterfeiting measures.
Are Coins a Better Match for QR Codes Than Banknotes?
Printing a QR code on a banknote is technically easy, but engraving a QR code on a coin has been considered difficult. However, with precise laser processing technology, it is possible to engrave a tiny QR code on the surface of a coin.
There are real examples, too. In June 2011, the Royal Dutch Mint (Koninklijke Nederlandse Munt) issued a coin engraved with a QR code to commemorate the 100th anniversary of its current building and grounds. This is said to be the first time in the world that a QR code was engraved on an official coin, and at the time of issue, scanning it gave access to a site introducing the coin's history and design. As with Nigeria's commemorative note, the purpose was not anti-counterfeiting but guiding people to commemorative content.
QR codes on coins have the advantage of being more durable than those on banknotes. On banknotes, there is a risk that folding and wear will make the QR code unreadable, but a QR code engraved in metal remains readable for a long time. It is fair to say that commemorative coins, as collector's items, are a good match for QR codes.