It's unknown how many authorities and government agencies are aware of this hidden feature and are using it to trace counterfeiters. What is for sure is that Dutch police forces know about the possibility and have solved cases with help from printer manufacturers.
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The Electronic Frontier Foundation does research and collects information, on technology and security issues. They have published a list of printers that do and those that don't leave hidden codes on printed work:
It appears that although consumers aren't aware of the hidden code on their color prints, government agencies are. And they are using this knowledge in their battle against counterfeiters -- with help from well-known printer manufacturers.
Canon is one of the companies willing to cooperate with authorities. Not to battle counterfeiters, but to 'protect their customers.'
"Canon takes the issue of security extremely seriously," said Anna McIntyre, PR manager at Canon Europe. "That is why Canon feels that early prevention is crucial and has fitted all its color machines with anti-counterfeit detection technology."
"Canon works closely with the relevant national and international authorities to ensure that the opportunities for its products to be misused are minimized. With security becoming increasingly important to businesses, Canon strives to ensure all its products leave organizations confident in the knowledge that its printer/copiers can only be used to produce legal documentation."
Sources familiar with the printer industry confirm this built-in security is in fact a unique number that is printed on every color page. The code, in yellow, can be printed on a line as thin as 0.1 millimeter.
With help from manufacturers like Canon, authorities can gather information about the printer used in counterfeit crimes. The number tells them in which country a specific printer has been delivered, and to what dealer. The dealer then can lead them to the local computer store where the printer was sold.
"We are familiar with this research method," said Ed Kraszewski of the Dutch national police agency KLPD. "We are using it in our research and it has proven to be successful in the past."
Even though the spokesman cannot detail what kind of successes or in what cases the agency is using this method now, anonymous sources confirm that the Dutch Railway Police, part of the KLPD, is investigating a gang that could be counterfeiting tickets on a large scale.
As part of the research in this case, officers have tracked down the printer used to print the fake tickets. They are now trying to get the name of the person who bought the printer. A local distributor in the Netherlands was visited by two officers with specific questions about the printer.
"Their research led them to our company," said the director of the big Dutch distributor, who wants to remain anonymous. "It concerned an investigation about counterfeit tickets. With the number they apparently found, they could see what engine was used. They knew exactly what printer was used and wanted to know to whom I had sold that specific printer."
The company's records only revealed in what batch the printer had arrived. The police left the building with specific sales information about that batch, which contained about a hundred printers. The investigation is still running, according to a spokesman for the team investigating this matter.
Recently, researchers at Purdue University in West Lafayette, Indiana, said they have developed a method that will enable authorities to trace documents to specific printers. This technique uses two methods to trace a document: first, by analyzing a document to identify characteristics that are unique for each printer, and second by designing printers to purposely embed individualized characteristics in documents.
Counterfeiters often digitally scan currency and then use color laser and inkjet printers to produce bogus bills. Forgers use the same methods to make fake passports and other documents.
"Investigators want to be able to determine that a fake bill or document was created on a certain brand and model of printer," said Edward J. Delp, a professor of electrical and computer engineering at Purdue.
So far, the researchers have only been able to successfully identify which model of printer was used to create certain documents in 11 out of 12 models tested. The researchers uses specialized software to detect slight variations in printed characters which they call "intrinsic signatures," revealing subtle differences from one printer model to another.
To prove that a specific printer was used by counterfeiters, authorities would need the printer itself to confirm their suspicions. This method is therefore not as accurate as the hidden mark included on color printouts by the printer manufacturers.