Secret print tracking

Sunday 25 November 2007

Erik Spiekermann has details on secret yellow dots used to track laser printer output. Seems most laser printers print yellow dots in a decodable pattern to track which printer printed the sheet, and when. The Electronic Frontier Foundation has more details (many of the links are broken, but you can fix them by changing the www2 prefix).

This is a fine example of technology used to spy on us in a very subtle way, and for a good cause, to defeat counterfeiters. But the same technology can also be used for ill, and it’s for that reason that techniques like this should be explained openly. After all, if the government’s reason for this tracking is to prevent counterfeiters, I think everyone would be for it. So why not make the whole technique public?

BTW: EFF has a list of printers which do and do not print tracking dots. I am an employee of Hewlett-Packard, which make a great many models which seem to do this tracking. I am a bit more appalled because I work for HP, but I do not work near enough to the printer group to have any insight into or control over this issue.

Comments

[gravatar]
Stuart Langridge 2:27 PM on 25 Nov 2007

I thought you were at Tabblo?

[gravatar]
Ned Batchelder 2:50 PM on 25 Nov 2007

I am, but Tabblo is part of HP.

[gravatar]
Stuart Langridge 2:57 PM on 25 Nov 2007

blimey!

I must have missed that announcement...

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JohnMc 3:17 PM on 25 Nov 2007

Yes the magic dots are present in a great many printers. But I have to tell you the dots are not invisible. They are a very faint shade of yellow which can be found if you look for them. But I would not worry that their presence as the coming uber totalitarian state.

If you are an anarchist looking to take over the world the easiest way to defeat the system is to print a full sheet background color that matches the dots along with your message. Nothing to detect then. But it does make it hard for the counterfeiters.

Besides there are easier ways now to find who did what. Most color printers today are essentially servers. Especially the networked ones. The who, what, where of a print job is sitting in the printer ready for interrogation. Fact if I was a spy one of the first systems I would want to compromise would be the printer of the secretary of the person of interest. I could very quickly see the entire correspondence of my target.

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