Printer steganography is a type of steganography

Steganography

Steganography is the art and science of writing hidden messages in such a way that no one, apart from the sender and intended recipient, suspects the existence of the message, a form of security through obscurity...

 produced by color printers, including Brother

Brother Industries

is a diversified Japanese company that produces or imports a wide variety of products including printers, sewing machines, large machine tools, label printers, and typewriters, fax machines, and other computer-related electronics. It markets its multifunction printers as Multi-Function Centers...

, Canon, Dell, Epson, HP, IBM, Konica Minolta

Konica Minolta

is a Japanese manufacturer of office equipment, medical imaging, graphic imaging, optical devices, and measuring instruments. It is headquartered in the Marunouchi Center Building in Marunouchi, Chiyoda, Tokyo, with a Kansai office in Nishi-ku, Osaka, Osaka Prefecture...

, Kyocera, Lanier, Lexmark, Ricoh, Toshiba and Xerox

Xerox

Xerox Corporation is an American multinational document management corporation that produced and sells a range of color and black-and-white printers, multifunction systems, photo copiers, digital production printing presses, and related consulting services and supplies...

 brand color laser printers, where tiny yellow dots are added to each page. The dots are barely visible and contain encoded printer serial numbers, as well as date and time stamps.

Color laser printers appear to be the type mostly involved, the measure being brought in during the 1990s by companies such as Xerox

Xerox

Xerox Corporation is an American multinational document management corporation that produced and sells a range of color and black-and-white printers, multifunction systems, photo copiers, digital production printing presses, and related consulting services and supplies...

 seeking to reassure governments that their printers would not be used for the purposes of forgery

Forgery

Forgery is the process of making, adapting, or imitating objects, statistics, or documents with the intent to deceive. Copies, studio replicas, and reproductions are not considered forgeries, though they may later become forgeries through knowing and willful misrepresentations. Forging money or...

. The identification is by means of a watermark

Watermark

A watermark is a recognizable image or pattern in paper that appears as various shades of lightness/darkness when viewed by transmitted light , caused by thickness or density variations in the paper...

, often using yellow-on-white, embedded in the printout of each page, and in conjunction with other information can be used to identify the printer which was used to print any document originally produced on a wide range of popular printers. It may be actual text, or a repeated pattern of dots throughout the page, more easily visible under blue light or with a magnifying glass, and is intended to be very difficult to notice with the naked eye.

In 2005, the Electronic Frontier Foundation

Electronic Frontier Foundation

The Electronic Frontier Foundation is an international non-profit digital rights advocacy and legal organization based in the United States...

 cracked the codes for DocuColor printers and published an online guide to their detection. Most printers' codes have not been decoded, although the coding system framework and printer serial number encoding is the same on both DocuColor and the Epson Aculaser C1100/C1100N/A.

See also

• Steganography
  Steganography
  Steganography is the art and science of writing hidden messages in such a way that no one, apart from the sender and intended recipient, suspects the existence of the message, a form of security through obscurity...
  
  
• Microprinting
  Microprinting
  Microprinting is one of many anti-counterfeiting techniques used most often on currency and bank checks, as well as various other items of value. Microprinting involves printing very small text, usually too small to read with the naked eye, onto the note or item. Microprint is frequently hidden in...
  
  
• Coded Anti-Piracy
  Coded Anti-Piracy
  Coded Anti-Piracy is an anti-copyright infringement technology which marks each film print of a motion picture with a distinguishing patterns of dots, used as a forensic identifier to identify the source of illegal copies....
  
  
• EURion constellation
  EURion constellation
  The EURion constellation is a pattern of symbols found on a number of banknote designs worldwide since about 1996. It is added to help software detect the presence of a banknote in a digital image. Such software can then block the user from reproducing banknotes to prevent counterfeiting using...
  
  
• Mobile phone tracking
  Mobile phone tracking
  Mobile phone tracking refers to the attaining of the current position of a mobile phone, stationary or moving. Localization may occur either via multilateration of radio signals between radio towers of the network and the phone, or simply via GPS...
  
  

External links

• Musgrove, Mike Sleuths Crack Tracking Code Discovered in Color Printers (October 19, 2005)
• Risks-L digest (October 26, 2005)
• DocuColor Tracking Dot Decoding Guide Electronic Frontier Foundation (October, 2005)
• Electronic Frontier Foundation information pages
• Electronic Frontier Foundation list of affected and non affected printers
• pcworld article 2004