Constellation of EURos on daily tickets

2011/02/01 Ruiz-Agundez, Igor - DeustoTech Computing, Deusto Institute of Technology. Deustuko Unibertsitatea | Nieves Acedo, Javier - DeustoTech Computing, Deusto Institute of Technology. Deustuko Unibertsitatea Iturria: Elhuyar aldizkaria

• Ingeniaritza
• Teknologia

What relationship do stars and banknotes have? Why can't you copy a ticket with color copiers? How can this technology help us? There are many secrets within a ticket, secrets that protect against forgery. Central banks and other international organizations around the world are developing protective measures. We all know some protection measures: watermarks, holograms and accessible bars. But besides all these techniques, and especially in euro banknotes, we can find small circles called constellations of EURion. This constellation is the basis for avoiding the reduction of banknotes in modern photocopiers and scanners. In addition, this protection measure is being expanded day by day and although it does not work on some photocopiers, it is expected to be implemented in the coming years.

Throughout history, there has always been a need to protect documents. Governments, companies and citizens must safeguard various documents (e.g. Tickets, certificates or cards). In addition, with current technologies, techniques have been improved to ensure the authenticity of documents.

However, this article explains what the constellation of the tickets is and what it serves. First, taking advantage of the work done, we have carried out two experiments to detect the light of the constellation of EURs. Finally, we have transferred the results obtained to another field to protect all types of documents.

Constellation of EURs

The constellation of EURs is a pattern symbol that can be found in the paper currency. It is not clear when and who created the pattern, because this data is not public, but Markus Kuhn discovered it in 2002 while investigating protection systems for photocopying paper currency (Murdoch, 2004). He wrote the first article on the subject. This pattern symbol created to detect the digital image of a bank ticket, if detected by a software program, paralyzes money forgery operations.

The relationship between the names of the constellations of EURion and Orio is not random. The constellation of Orion is one of the most well-known constellations in the sky. It can be observed in the two terrestrial hemispheres (in the northern hemisphere in winter and in the south in summer) and its appearance is very similar to that of EURion. As can be seen in Figure 1, the constellation of EURs is a simplification of Orion, as the Orion belt is replaced by a single point.

More specifically, the constellation of EURion is a five-point pattern. The points can be yellow, green or orange. Normally, the pattern appears in monetary papers several times and in different geometric orientations. However, once the pattern appears, it is sufficient to be detected.

There are no official names to designate this protection feature of the paper currency. Other researchers have called it "Omrong rings". The technical data are secret and there is little bibliography published. However, there are several countries in the world that use this security measure, from the dramas of Armenia to US dollars.

Reverse engineering of the constellation of EURs

The steps below are the reverse engineering process used to analyze the characteristics of the constellation of EURs. The main objective of our experiment is to synthesize a single constellation of EURion. For this we have used a ticket of ten euros and a multipurpose printer. It should be mentioned that this experiment works with any euro banknote, since all have the protective measure of the constellation of EURs. However, the printer used may not have implemented this protection measure and copy money. It is expected that all photocopiers built in the coming years will have this measure.

To begin with, we have tried to photocopy the ticket shown in figure 2. Due to the protection policies we have previously exposed, the result that the printer has given us has been a black sheet. Through this test, the operation of the protection system has been verified.

The next test consists of photocopying the ticket vertically to perform four different subtests. Figure 3 shows only the one on the left of the constellation of the AMR of the ticket. This photocopy subtest part of the ticket but does not activate any protection system. In figure 4 you can only see the one on the right of the constellation of EURion of the ticket. In this subtest we also have the photocopy of part of the ticket and we can recopy it without any problem. Figure 5 has hidden the one on the right of the constellation EURion of the banknote and the constellation itself has been revealed. This subtest shows us a black photocopy and we have found that the protection system is activated. Figure 6 has hidden the one on the left of the constellation of the RAINS of the ticket. The result of this subtest is also a black page, due to the reactivation of the protection system. Applying to these last four tests the intersection and symmetric difference of the algebraic theory of the subsets, it is concluded that the protection system is mathematically located in the field of the constellation of EURion.

To assess otherwise the impact of the previous tests, we have photocopied the ticket horizontally and have made two subtests. Figure 7 hides the top of the centre of the ticket and figure 8 the bottom of the centre. When photocopying both images, a black image is obtained and the effect of the constellation of EURs is checked.

Figure 9 shows the only constellation of EURs represented by previous studies (Kuhn, 2002). With this single part of the ticket, protection systems are activated and when photocopying a black image is taken out. In Figure 10 we have hidden one of the five points. In this case, the photocopy goes well and we have found that the five points are necessary.

However, it remains to be demonstrated the importance of the color of the constellation of EURs. In figure 11, the constellation circles have been painted with pencil. When photocopying we will obtain a suitable copy. With this test we have shown the importance of the color of circles.

Once we have reached this point, we have obtained information to synthesize a constellation of EURion. We have found that printers and programs specifically prepared for this part of a ticket will activate protection systems.

Synthesis of EURion

The experiment presented in the previous section has allowed us to carry out an inverse engineering to the constellation of EURs. In this section we have created an artificial synthesis of the constellation of EURion. For this we have left the artificial image that Markus Kuhn published. See figure 1.

However, if you try to photocopy this image, no protection measures will be activated. We must adapt the image to the analyzed characteristics. To do this, the first step is to adapt to the actual measurements of the constellation of EURs. Figure 12 represents the diameter of the points and distances between them.

The second step is to take into account the colors. Photocopying the previous image in black and white will not be activated security measures. As we have said, constellation circles should be yellow, green, or orange.

At first, in our experiment we colored the circles in green and, when photocopying in color, the protective measures remained unactivated. That's why we did the test with yellow, but the result was also negative.

Theoretically we have synthesized the perfect constellation of EURion, although the protective measures still do not work. The only difference between the constellation of coin notes and ours is found in the subsequent stamping of banknotes. To reduce the effect of this difference we have "put noise" into our constellation. A pixel or a pair of points of another color has been added. When trying to photocopy this last synthesized version, security measures have been activated and we have only achieved a black sheet.

Beyond the stars, new uses

Once the constellation of EURion is synthesized, we can activate protection systems to avoid money copies on a printer when we want. We will show that although these sponsorships have been created to avoid money forgery, they can also be used for other applications. This allows us to protect not only banknotes, but also other types of documents, such as the apparent confidential document shown in Figure 13.

This has already been possible (Blum, 2004). So far, however, there has been no one capable of protecting all kinds of documents. Thanks to our synthesized constellation we have created a global brand of water that protects it from photocopies.

By pasting this watermark, the document will be incopiable. The possible applications of the constellation of EURs can be broad: maintain the originality of concert tickets, ensure the simplicity of exams, protect confidential internal documents from companies, etc. We could deploy the protective reflection of the constellation of EURs to any field we can imagine.

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