Printer tracking dots, also known as printer steganography, DocuColor tracking dots, yellow dots, secret dots, or a machine identification code (MIC), is a digital watermark which many color laser printers and photocopiers produce on every printed page that identifies the specific device that was used to print the document. Developed by Xerox and Canon in the mid-1980s, the existence of these tracking codes became public only in 2004.
In the mid-1980s, Xerox pioneered an encoding mechanism for a unique number represented by tiny dots spread over the entire print area, and first deployed this scheme in its DocuColor line of printers. Xerox developed this surreptitious tracking code "to assuage fears that their color copiers could be used to counterfeit bills" [1] and received U.S. Patent No. 5515451 describing the use of the yellow dots to identify the source of a copied or printed document. [2] [3] The scheme was then widely deployed in other printers, including those made by other manufacturers.
The public first became aware of the tracking scheme in October 2004, when Dutch authorities used it to track counterfeiters who had used a Canon color laser printer. [4] In November 2004, PC World reported the machine identification code had been used for decades in some printers, allowing law enforcement to identify and track counterfeiters. [1] The Central Bank Counterfeit Deterrence Group (CBCDG) has denied that it developed the feature. [2]
In 2005, the civil liberties activist group Electronic Frontier Foundation (EFF) encouraged the public to send in sample printouts and subsequently decoded the pattern. [5] The pattern has been demonstrated on a wide range of printers from different manufacturers and models. [6] The EFF stated in 2015 that the documents that they previously received through a Freedom of Information Act request [7] suggested that all major manufacturers of color laser printers entered a secret agreement with governments to ensure that the output of those printers is forensically traceable. [6]
Although we still don't know if this is correct, or how subsequent generations of forensic tracking technologies might work, it is probably safest to assume that all modern color laser printers do include some form of tracking information that associates documents with the printer's serial number. (If any manufacturer wishes to go on record with a statement to the contrary, we'll be happy to publish that here.)
In 2007, the European Parliament was asked about the question of invasion of privacy. [8] [2]
The pattern consists of a dot-matrix spread of yellow dots, which can barely be seen with the naked eye. The dots have a diameter of a tenth of a millimeter (0.004") and a spacing of about one millimeter (0.039"). Their arrangement encodes the serial number of the device, date and time of the printing, and is repeated several times across the printing area in case of errors. For example, if the code consists of 8 × 16 dots in a square or hexagonal pattern, it spreads over a surface of about 4 square centimetres (0.62 sq in) and appears on a sheet of size A4 paper about 150 times. Thus, it can be analyzed even if only fragments or excerpts are available. Some printers arrange yellow dots in seemingly random point clouds.
According to the Chaos Computer Club in 2005, color printers leave the code in a matrix of 32 × 16 dots and thus can store 64 bytes of data (64×8). [9]
As of 2011 [update] , Xerox was one of the few manufacturers to draw attention to the marked pages, stating in a product description, "The digital color printing system is equipped with an anti-counterfeit identification and banknote recognition system according to the requirements of numerous governments. Each copy shall be marked with a label which, if necessary, allows identification of the printing system with which it was created. This code is not visible under normal conditions." [10]
In 2018, scientists at the TU Dresden analyzed the patterns of 106 printer models from 18 manufacturers and found four different encoding schemes. [11]
The dots can be made visible by printing or copying a page and subsequently scanning a small section with a high-resolution scanner. The yellow color channel can then be enhanced with an image processing program to make the dots of the identification code clearly visible. Under good lighting conditions, a magnifying glass may be enough to see the pattern. Under UV-light, the yellow dots are clearly recognizable. [12]
Using this steganographic process, high-quality copies of an original (e.g. a banknote) under blue light can be made identifiable. Using this process, even shredded prints can be identified: the 2011 "Shredder Challenge" initiated by the DARPA was solved by a team called "All Your Shreds Are Belong To U.S." consisting of Otávio Good and two colleagues. [13] [14]
Both journalists and security experts have suggested that The Intercept 's handling of the leaks by whistleblower Reality Winner, which included publishing secret NSA documents unredacted and including the printer tracking dots, was used to identify Winner as the leaker, leading to her arrest in 2017 and conviction. [15] [16]
Copies or printouts of documents with confidential personal information, for example health care information, account statements, tax declaration or balance sheets, can be traced to the owner of the printer and the inception date of the documents can be revealed. This traceability is unknown to many users and inaccessible, as manufacturers do not publicize the code that produces these patterns. It is unclear which data may be unintentionally passed on with a copy or printout. In particular, there are no mentions of the technique in the support materials of most affected printers. In 2005, the Electronic Frontier Foundation (EFF) sought a decoding method and made available a Python script for analysis. [17]
In 2018, scientists from TU Dresden developed and published a tool to extract and analyze the steganographic codes of a given color printer and subsequently to anonymize prints from that printer. The anonymization works by printing additional yellow dots on top of the printer's tracking dots. [18] [11] [19] The scientists made the software available to support whistleblowers in their efforts to publicize grievances. [20]
Other methods of identification are not as easily recognizable as yellow dots. For example, a modulation of laser intensity and a variation of shades of grey in texts are feasible. As of 2006 [update] , it was unknown whether manufacturers were also using these techniques. [21]
In computing, a printer is a peripheral machine which makes a durable representation of graphics or text, usually on paper. While most output is human-readable, bar code printers are an example of an expanded use for printers. Different types of printers include 3D printers, inkjet printers, laser printers, and thermal printers.
Xerox Holdings Corporation is an American corporation that sells print and digital document products and services in more than 160 countries. Xerox is headquartered in Norwalk, Connecticut, though it is incorporated in New York with its largest population of employees based around Rochester, New York, the area in which the company was founded. The company purchased Affiliated Computer Services for $6.4 billion in early 2010. As a large developed company, it is consistently placed in the list of Fortune 500 companies.
Laser printing is an electrostatic digital printing process. It produces high-quality text and graphics by repeatedly passing a laser beam back and forth over a negatively charged cylinder called a "drum" to define a differentially charged image. The drum then selectively collects electrically charged powdered ink (toner), and transfers the image to paper, which is then heated to permanently fuse the text, imagery, or both to the paper. As with digital photocopiers, laser printers employ a xerographic printing process. Laser printing differs from traditional xerography as implemented in analog photocopiers in that in the latter, the image is formed by reflecting light off an existing document onto the exposed drum.
Dot matrix printing, sometimes called impact matrix printing, is a computer printing process in which ink is applied to a surface using a relatively low-resolution dot matrix for layout. Dot matrix printers are a type of impact printer that prints using a fixed number of pins or wires and typically use a print head that moves back and forth or in an up-and-down motion on the page and prints by impact, striking an ink-soaked cloth ribbon against the paper. They were also known as serial dot matrix printers. Unlike typewriters or line printers that use a similar print mechanism, a dot matrix printer can print arbitrary patterns and not just specific characters.
A barcode or bar code is a method of representing data in a visual, machine-readable form. Initially, barcodes represented data by varying the widths, spacings and sizes of parallel lines. These barcodes, now commonly referred to as linear or one-dimensional (1D), can be scanned by special optical scanners, called barcode readers, of which there are several types.
Daisy wheel printing is an impact printing technology invented in 1970 by Andrew Gabor at Diablo Data Systems. It uses interchangeable pre-formed type elements, each with typically 96 glyphs, to generate high-quality output comparable to premium typewriters such as the IBM Selectric, but two to three times faster. Daisy wheel printing was used in electronic typewriters, word processors and computers from 1972. The daisy wheel is so named because of its resemblance to the daisy flower.
Dots per inch is a measure of spatial printing, video or image scanner dot density, in particular the number of individual dots that can be placed in a line within the span of 1 inch (2.54 cm). Similarly, dots per centimetre refers to the number of individual dots that can be placed within a line of 1 centimetre (0.394 in).
A microdot is text or an image substantially reduced in size to prevent detection by unintended recipients. Microdots are normally circular and around 1 millimetre (0.039 in) in diameter but can be made into different shapes and sizes and made from various materials such as polyester or metal. The name comes from microdots often having been about the size and shape of a typographical dot, such as a period or the tittle of a lowercase i or j. Microdots are, fundamentally, a steganographic approach to message protection.
A canary trap is a method for exposing an information leak by giving different versions of a sensitive document to each of several suspects and seeing which version gets leaked. It could be one false statement, to see whether sensitive information gets out to other people as well. Special attention is paid to the quality of the prose of the unique language, in the hopes that the suspect will repeat it verbatim in the leak, thereby identifying the version of the document.
Thermal-transfer printing is a digital printing method in which material is applied to paper by melting a coating of ribbon so that it stays glued to the material on which the print is applied. It contrasts with direct thermal printing, where no ribbon is present in the process.
The EURion constellation is a pattern of symbols incorporated into a number of secure documents such as banknotes, cheques, and ownership title certificates designs worldwide since about 1996. It is added to help imaging software detect the presence of such a document in a digital image. Such software can then block the user from reproducing banknotes to prevent counterfeiting using colour photocopiers.
Security printing is the field of the printing industry that deals with the printing of items such as banknotes, cheques, passports, tamper-evident labels, security tapes, product authentication, stock certificates, postage stamps, and identity cards. The main goal of security printing is to prevent forgery, tampering, or counterfeiting. More recently many of the techniques used to protect these high-value documents have become more available to commercial printers, whether they are using the more traditional offset and flexographic presses or the newer digital platforms. Businesses are protecting their lesser-value documents such as transcripts, coupons and prescription pads by incorporating some of the features listed below to ensure that they cannot be forged or that alteration of the data cannot occur undetected.
Variable Data Intelligent Postscript Printware is an open language from Xerox that enables highest-performance output of variable-data PostScript documents. It is used by the FreeFlow VI Suite (VIPP) front end.
Microprinting is the production of recognizable patterns or characters in a printed medium at a scale that typically requires magnification to read with the naked eye. To the unaided eye, the text may appear as a solid line. Attempts to reproduce by methods of photocopy, image scanning, or pantograph typically translate as a dotted or solid line, unless the reproduction method can identify and recreate patterns to such scale. Microprint is predominantly used as an anti-counterfeiting technique, due to its inability to be easily reproduced by widespread digital methods.
Digital paper, also known as interactive paper, is patterned paper used in conjunction with a digital pen to create handwritten digital documents. The printed dot pattern identifies the position coordinates on the paper. The digital pen uses this pattern to store handwriting and upload it to a computer.
In the distribution and logistics of many types of products, track and trace or tracking and tracing concerns a process of determining the current and past locations of a unique item or property. Mass serialization is the process that manufacturers go through to assign and mark each of their products with a unique identifier such as an Electronic Product Code (EPC) for track and trace purposes. The marking or "tagging" of products is usually completed within the manufacturing process through the use of various combinations of human readable or machine readable technologies such as DataMatrix barcodes or RFID.
DocuTech is the name given to a line of electronic production-publishing systems produced by Xerox Corporation. It allowed paper documents to be scanned, electronically edited, and then printed on demand. DocuTech systems were the last known to use the XNS protocol for networking.
A photocopier is a machine that makes copies of documents and other visual images onto paper or plastic film quickly and cheaply. Most modern photocopiers use a technology called xerography, a dry process that uses electrostatic charges on a light-sensitive photoreceptor to first attract and then transfer toner particles onto paper in the form of an image. The toner is then fused onto the paper using heat, pressure, or a combination of both. Copiers can also use other technologies, such as inkjet, but xerography is standard for office copying.
The Electronic Frontier Foundation (EFF) is an international non-profit advocacy and legal organization based in the United States and serves its operations worldwide.
The Xerox 9700 was a high-end laser printer manufactured by Xerox Corporation beginning in 1977. Based on the Xerox 9200 copier, the 9700 printed at 300 dots-per-inch on cut-sheet paper at up to two pages per second (pps), one- or two-sided, that is simplex or duplex, landscape or portrait.
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