Talk:Printer steganography

Reality Winner
That hasn't been confirmed and is based on widespread speculation. Although researchers found yellow-dot printer steganography in the NSA document, the FBI affidavit does not say they were used in the investigation. The affifavit notes that the document had been printed out, that Winner was one of six people who printed it, and they caught her because she also emailed The Intercept from her work computer. Affidavit is here:

https://www.justice.gov/opa/press-release/file/971331/download

I wrote about the topic in some depth on Quartz here:

https://qz.com/1002927/computer-printers-have-been-quietly-embedding-tracking-codes-in-documents-for-decades/

Microdots?
My impression from the EFF materials is that we are dealing with microdots. Did I get it wrong? (The DocuColor series prints a rectangular grid of 15 by 8 miniscule yellow dots on every color page. The same grid is printed repeatedly over the entire page, but the repetitions of the grid are offset slightly from one another so that each grid is separated from the others. The grid is printed parallel to the edges of the page, and the offset of the grid from the edges of the page seems to vary. These dots encode up to 14 7-bit bytes of tracking information, plus row and column parity for error correction. Typically, about four of these bytes were unused (depending on printer model), giving 10 bytes of useful data. Below, we explain how to extract serial number, date, and time from these dots. Following the explanation, we implement the decoding process in an interactive computer program).Joaquin Murietta 07:39, 2 November 2005 (UTC)


 * Not at all. A microdot is a miniaturized photograph downscaled to the size of a dot. This is a pattern of individual dots without finer internal structure. --Shaddack 02:45, 22 January 2007 (UTC)

Timestamps?
I understand how the printers can do serial numbers, since these are obviously embedded in the firmware or some other ROM/Flash IC. But how do they do timestamps? Do their timestamps depend on the administrator having correctly configured the time in the HTTP setup interface? Or do they try to access NTP servers via the network or something? Would be interesting to know how that works... Moxfyre 05:08, 7 February 2007 (UTC)

When the equipment is setup for the first time or rebuilt, the date and time is configured. Jeffz1 (talk) 00:32, 25 May 2009 (UTC)

Additional Manufacturer
Today I observed the pattern on a Ricoh Aficio MP C4500. LorenzoB (talk) 05:35, 21 October 2010 (UTC)

I have failed to observe any pattern or markings whatsoever on the HP Colour Lazer Jet Pro MFP M177fw 09:42, 28 March 2017 (UTC)

DocuColor and Epson Aculaser similarity
This line seems a bit unclear, not to mention uncited. Is this original research? I can't find it anywhere on either of the EFF pages linked. Also, when it says "printer serial number encoding" it means that the ordering for the date, hour, minute and serial number is the same as well as number of bits in the serial number, correct? MecuryTACAMO --(talk) 12:32, 19 August 2016 (UTC)

Merge with Machine Identification Code
Looks like two articles on the same subject. --NetRolller 3D  18:30, 11 July 2017 (UTC)
 * Yes, supported. Tøpholm (talk) 13:43, 16 April 2018 (UTC)

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