Many things

From: Tom Jennings <tomj_at_wps.com>
Date: Mon Jan 31 13:40:11 2005

On Mon, 31 Jan 2005, der Mouse wrote:

>> 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.

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.

> 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_at_wps.com>
Received on Mon Jan 31 2005 - 13:40:11 GMT