31 Jan
2005
31 Jan
'05
5:40 a.m.
On Mon, 31 Jan 2005, der Mouse wrote:
The stories say it's in the printer/scanner, but I wonder about that.
For the scanner, the circumstances point to it being in the
driver; identifying a pattern (eg. the little "20"s on the bill)
is probably too big (still) to embed in the printer; they noticed
something was up when the new driver recommended download was >
100 MB!
For the printer, it's entirely possible it's in the printer; I can
imagine that it depends on the type of output or document size or
something, but all it has to do is output a pixel pattern that's
likely hashed and well-distributed. The pattern by design won't
change per-image, only per-printer.
Done! Most
recent HP drivers for their scanners prevent copying of
newer US$20 bills. Tosses you to an anti-counterfeit website!
Windows of course.
As long as the interface is documented enough for open-source support,
and the bugs aren't in the scanner itself, I'm fine with that. If I caught my printer doing that, I would tell them
to fix it. If
they tried to claim it was a feature, or otherwise refused, I'd return
it and find a printer that printed what - and nothing but what - it was
given to print.
Good luck! :-)
Tom Jennings <tomj(a)wps.com>