Privacy worries? Don't Print in Color
By Hiawatha Bray
You've got to love black-and-white laser printers. You can get a good
one for $150 or so, and each toner cartridge cranks out thousands of
pages before you need a refill. Best of all, they don't spy on you.
You can't say the same about color laser printers, as we learned last
week. Actually, we should have learned it nearly a year ago. That's
when PC World magazine reported that makers of color laser printers,
in cooperation with law enforcement agencies, have programmed their
machines to print tiny yellow dots on every printed document. These
dots are almost invisible under normal conditions, but can be spotted
by anyone with a magnifier and the right sort of lighting.
Most of us ignored the news, but not the civil libertarians at the
Electronic Frontier Foundation in San Francisco. The group asked its
members to mail in documents generated by dozens of color laser
printers. They got hundreds of submissions run off on printers made
by a variety of manufacturers -- Minolta, Canon, Hewlett-Packard and
Xerox, among others.
Last week, the foundation announced it had cracked the code on a
document generated by a Xerox printer. By reading the yellow dots,
staff members were able to identify the serial number of the very
machine that had produced the printout.
No big deal, unless you're a counterfeiter. "Ten years ago, 1
percent of counterfeit currency was produced by copiers and printers;
now it's 56 percent," said Eric Zahren, spokesman for the US Secret
Service, the government agency that battles the funny-money trade. So
the Secret Service and other security agencies persuaded printer
makers to embed subtle markers into their machines. And not just
printers, said Edward Delp, a professor of electrical engineering at
Purdue University. "Color copiers have done this for a long time,"
As a result, police can play spot-the-dots with pieces of phony
currency, then use sales records to trace the machine and its owner.
Of course, the same technique can be used to identify anything else
from the printer. But Zahren says privacy-conscious citizens have
nothing to fear. "You only have to worry about it identifying you if
you have partaken in illegal activity," he said.
Famous last words? Maybe not. Why would cops bother to inspect the
billions of pages printed every day, just to figure out which printer
produced them? It might be worthwhile to study anonymous ransom notes
or death threats. But usually it's obvious where a document came from;
the cops needn't bother looking for subtle yellow dots.
Then again, few of us live in countries with a low regard for human
rights. Pity the poor Cuban worshiper at a secret church who cranks
out a few religious tracts on the office laser printer. Let one of
those tracts fall into an informant's hands, and the cops will know
exactly where to find him.