printer tracking dots

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"{{cite news |first=Jason |last=Tuohey |url=https://www.pcworld.com/article/118664/article.html |title=Government Uses Color Laser Printer Technology to Track Documents |work=PC World |date=22 November 2004 |access-date=December 3, 2019 |archive-date=August 8, 2019 |archive-url=https://web.archive.org/web/20190808105321/https://www.pcworld.com/article/118664/article.html |url-status=dead}} and received U.S. Patent No. 5515451 describing the use of the yellow dots to identify the source of a copied or printed document.{{cite patent|number=US5515451A|title=Image processing system for selectively reproducing documents|gdate=1996-05-07|invent1=Tsuji|invent2=Seki|invent3=Leng|invent4=Aikawa|inventor1-first=Masato|inventor2-first=Masao|inventor3-first=Svay|inventor4-first=Koji|url=https://patents.google.com/patent/US5515451A/en}} 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.{{cite news |first=Wilbert |last=de Vries |url=https://www.pcworld.idg.com.au/article/8305/dutch_track_counterfeits_via_printer_serial_numbers/ |title=Dutch track counterfeits via printer serial numbers |work=PC World |date=26 October 2004 |archive-url=https://web.archive.org/web/20090624033632/https://www.pcworld.idg.com.au/article/8305/dutch_track_counterfeits_via_printer_serial_numbers/ |archive-date=June 24, 2009}} 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. The Central Bank Counterfeit Deterrence Group (CBCDG) has denied that it developed the feature.

File:Machine Identification Code von Druckern.png

In 2005, the civil liberties activist group Electronic Frontier Foundation (EFF) encouraged the public to send in sample printouts and subsequently decoded the pattern.{{cite web |title=DocuColor Tracking Dot Decoding Guide |url=https://w2.eff.org/Privacy/printers/docucolor/ |date=2005 |website=Electronic Frontier Foundation |access-date=5 July 2018 |url-status=dead |archive-url=https://web.archive.org/web/20180305181029/https://w2.eff.org/Privacy/printers/docucolor/ |archive-date=5 March 2018 |language=en}} The pattern has been demonstrated on a wide range of printers from different manufacturers and models. The EFF stated in 2015 that the documents that they previously received through a Freedom of Information Act request{{cite letter|first=Robert|last=Lee|recipient=Latita M. Huff|subject=Freedom of Information Act (FOIA) request|language=EN|date=2005-07-27|url=https://www.eff.org/files/foia_letter.pdf|format=PDF|access-date=2016-11-07|publisher=Electronic Frontier Foundation}} 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.{{cite web|url=https://www.eff.org/pages/list-printers-which-do-or-do-not-display-tracking-dots|title=List of Printers Which Do or Do Not Display Tracking Dots |website=Electronic Frontier Foundation|date=September 20, 2007|access-date=2018-12-10}}

{{Blockquote|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.)|source=Electronic Frontier Foundation (2017)}}

In 2007, the European Parliament was asked about the question of invasion of privacy.{{cite news |publisher=European Parliament |url=http://www.europarl.europa.eu/sides/getDoc.do?reference=E-2007-5724&language=EN |title=Tracking codes in photocopiers and colour laser printers |work=Parliamentary questions |date=20 November 2007}}{{cite news |first=Stephan |last=Escher |url=https://www.deutschlandfunk.de/farblaserdrucker-tracking-dots-unlesbar-machen.676.de.html?dram:article_id=421558 |title=Tracking Dots unlesbar machen: Interview mit Uli Blumenthal |work=Deutschlandfunk |date=28 June 2018 |language=de}}

File:MIC 60x.jpg

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 {{convert|1/10|mm|in|spell=in|sigfig=1}} and a spacing of about {{convert|1|mm|in|spell=in|sigfig=1}}. 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 {{convert|4|cm2|sqin}} 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).{{cite book |author=Frank Rosengart |publisher= Chaos Computer Club |chapter= Datenspur Papier |title= Die Datenschleuder, Das wissenschaftliche Fachblatt für Datenreisende |journal= Datenschleuder |trans-title= technical factsheet |number=86 |location= Hamburg |year=2005 |pages=19–21 |issn=0930-1054 |chapter-url= https://chaosradio.ccc.de/media/ds/ds086.pdf |access-date=2011-02-27}}

{{As of|2011}}, 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."{{cite book |publisher= Xerox GmbH |title= Xerox DocuColor® 6060 Digitales Farbdrucksystem |type= Prospectus |location= Neuss |chapter= Abschnitt „Technische Daten des Digitalen Farbdrucksystems Xerox DocuColor 6060" |pages=8 |chapter-url= https://www.xerox.com/downloads/deu/de/7/708P86985DED.pdf |chapter-format= PDF; 1,4 MB |access-date= 2011-02-27}}

In 2018, scientists at the TU Dresden analyzed the patterns of 106 printer models from 18 manufacturers and found four different encoding schemes.

File:HP Color Laserjet 3700 schutz g.jpg

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.{{cite web |url=https://www.druckerchannel.de/artikel.php?ID=1239 |title=Beitrag bei Druckerchannel: Big Brother is watching you: Code bei Farblasern entschlüsselt |work=Druckerchannel.de |date=October 26, 2005 }}

File:Machine Identification Code.png

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.{{cite web |website= Defense Advanced Research Projects Agency |url= http://archive.darpa.mil/shredderchallenge/ |title= CONGRATULATIONS to "All Your Shreds Are Belong To U.S."! |date= 2011-11-21 |access-date= 2014-06-12 |archive-url= https://web.archive.org/web/20160825060146/http://archive.darpa.mil/shredderchallenge/ |archive-date= August 25, 2016 |url-status= dead }}{{cite news |work=Bloomberg Businessweek |url=https://www.bloomberg.com/news/articles/2011-12-15/tip-for-bad-guys-burn-dont-shred |archiveurl=https://web.archive.org/web/20160624160747/https://www.bloomberg.com/news/articles/2011-12-15/tip-for-bad-guys-burn-dont-shred |archivedate=2016-06-24 |title=Tip for Bad Guys: Burn, Don't Shred |date=2011-12-15 |access-date=2025-01-21 |first=Douglas |last=MacMillan}}

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.{{cite news|url=https://digg.com/2017/did-intercept-burn-reality-winner|work=Digg|date=June 6, 2017 |title=Did The Intercept Betray Its NSA Source With Sloppy Reporting?|first=L.V.|last=Anderson|archive-url=https://web.archive.org/web/20190101223854/http://digg.com/2017/did-intercept-burn-reality-winner|archive-date=January 1, 2019|url-status=live}}{{cite news|date=June 6, 2017|url=https://www.washingtonpost.com/blogs/erik-wemple/wp/2017/06/06/did-the-intercept-bungle-nsa-leak/|title=Did the Intercept bungle the NSA leak?|first=Erik|last=Wemple|newspaper=The Washington Post|archive-url=https://web.archive.org/web/20180713231635/https://www.washingtonpost.com/blogs/erik-wemple/wp/2017/06/06/did-the-intercept-bungle-nsa-leak/|archive-date=July 13, 2018|url-status=live}}

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.{{cite web |url=https://w2.eff.org/Privacy/printers/docucolor/docucolor.cgi |title=docucolor.cgi - CGI script to interpret Xerox DocuColor forensic dot pattern |date=2005 |website=Electronic Frontier Foundation |access-date=2018-10-03 |url-status=dead |archive-url=https://web.archive.org/web/20170508122630/https://w2.eff.org/Privacy/printers/docucolor/docucolor.cgi |archive-date=2017-05-08}}

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.DEDA - tracking Dots Extraction, Decoding and Anonymisation toolkit: {{GitHub|dfd-tud/deda}}{{Cite book|last1=Richter|first1=Timo|last2=Escher|first2=Stephan|last3=Schönfeld|first3=Dagmar|last4=Strufe|first4=Thorsten|title=Proceedings of the 6th ACM Workshop on Information Hiding and Multimedia Security |chapter=Forensic Analysis and Anonymisation of Printed Documents |date=2018-06-14|chapter-url=https://dl.acm.org/citation.cfm?id=3206004.3206019|publisher=ACM|pages=127–138|doi=10.1145/3206004.3206019|isbn=9781450356251|s2cid=49345609}}{{Cite web|url=https://www.heise.de/newsticker/meldung/Dresdner-Forscher-ueberlisten-Tracking-Punkte-bei-Laserdruckern-4090876.html|title=Dresdner Forscher überlisten Tracking-Punkte bei Laserdruckern|date=25 June 2018|website=heise online|language=de-DE}} The scientists made the software available to support whistleblowers in their efforts to publicize grievances.{{cite news |url=https://www.deutschlandfunknova.de/nachrichten/it-sicherheit-so-verpfeift-dich-dein-drucker-nicht |title=So verpfeift dich dein Drucker nicht |date=26 June 2018 |work=Deutschlandfunk Nova |language=de}}

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}}, it was unknown whether manufacturers were also using these techniques.{{cite web |url=https://engineering.purdue.edu/~prints/outreach/CERIAS_POSTER_2006.pdf |title=Printer Characterization and Signature Embedding for Security and Forensic Applications |first1=Pei-Ju |last1=Chiang |first2=Aravind K. |last2=Mikkilineni |first3=Sungjoo |last3=Suh |first4=Jan P. |last4=Allebach |author4-link=Jan P. Allebach |first5=George T.-C. |last5=Chiu |first6=Edward J. |last6=Delp |publisher=Purdue University |work=CERIAS Security Seminar |date=2006 |access-date=June 9, 2017 |archive-date=August 22, 2017 |archive-url=https://web.archive.org/web/20170822055028/https://engineering.purdue.edu/~prints/outreach/CERIAS_POSTER_2006.pdf |url-status=dead }}

• EURion constellation, a dot matrix spread over a bank note, which stops some printers and color copiers from processing
• {{Section link|Taggant|Explosive taggants}}
• {{Section link|Typewriter|Forensic examination}}

{{Reflist}}

• [https://bigbrotherawards.de/2004/technik-canon Laudatio der deutschen BigBrotherAwards 2004] {{inlang|de}}
• [http://dasalte.ccc.de/colorcopy/ Information by the Chaos Computer Club] {{Webarchive|url=https://web.archive.org/web/20170313130611/http://dasalte.ccc.de/colorcopy/ |date=March 13, 2017 }}
• [https://www.eff.org/Privacy/printers/ Information by the Electronic Frontier Foundation]
• [https://www.eff.org/pages/list-printers-which-do-or-do-not-display-tracking-dots EFF List of Printers Which Do or Do Not Display Tracking Dots] (last updated 2017)

Category:Identity documents

Category:Printing software

Category:Privacy software

Category:Steganography

Category:Watermarking

Category:Computer-related introductions in the 1980s

Category:Money forgery

Category:Hardware restrictions