Interesting new stego application

Hal Finney hal at
Fri Mar 23 13:18:25 EDT 2007

Udhay Shankar N <udhay at> writes:
> A technology that can "hide" information in plain sight on printed 
> images has begun to see the first commercial applications.
> ...
> Fujitsu's technique works by taking advantage of the sensitivities of 
> the human eye, which struggles to see the colour yellow.
> "The key is to take the yellow hue in the picture and we skew that 
> ever so slightly to create a pattern," said Mr Nelson.

This has been in use for years to watermark documents from certain
printers to enable forensic tracking of which printer produced a given
document, as well as when the document was printed.  It is presumed
that this is for the assistance of law enforcement.  The EFF has a good
article on about it at .

Hal Finney

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