AS 2002 was rung in, 拢400 billion worth of euro banknotes became legal
tender in 12 European countries. In an instant the euro became the largest
currency in the world after the dollar, and far bigger than any of those it
replaced. The switch brings with it a vast and unprecedented economic
opportunity鈥攆or counterfeiters.
Forgery is an activity as old as money itself, and it鈥檚 still flourishing.
According to Britain鈥檚 National Criminal Intelligence Service (NCIS), in 1996
over 拢10 million of counterfeit notes were seized in the UK alone. The
huge number of euro notes now in circulation makes them an irresistible target
for ripping off, and with so many people laying their eyes on this new currency
for the first time, passing off fakes has never been easier. 鈥淲e anticipate
there鈥檒l be a substantial interest in counterfeiting the new currency,鈥� said
Edward Venning of the NCIS just before the launch. And sure enough, at least
five cases of counterfeit notes turned up in the first week of January,
including a Finn who tried to pass a dodgy &egr;300 note鈥攅ven though no such
denomination exists.
Every new euro note is peppered with security features to make accurate
counterfeiting nigh on impossible. But many forgers don鈥檛 worry about these
subtle features because most of us are so slapdash about checking our cash. To
make notes really secure, banks need to include large and obvious security
features that are also very hard to fake, and that may mean a big change of
direction鈥攗sing plastic instead of paper.
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Plastic notes were introduced in Australia in 1988, and the challenge of
replicating them is thought to account for the country鈥檚 huge reduction in
counterfeiting. Plastic can incorporate the latest high-tech security features,
but more importantly it makes it far easier to spot a forgery at a glance.
That鈥檚 not to say that making fake euro notes is simple. Each genuine note
carries five basic security features. A watermark and thread are built into all
of the notes as the paper is made, and raised print runs along the top of each
note. Denominations of &egr;20 and below each have a foil strip with a hologram, and
an iridescent stripe that shines under bright light. Higher
denominations鈥攆rom &egr;50 to &egr;500鈥攆eature
instead a holographic patch, as well as ink that changes colour from purple
to olive-green or brown as you tilt the note.
These easily visible security features are just the start. A second level of
measures is included for the benefit of people who routinely handle large
amounts of cash, such as shopkeepers and bank tellers, and for automated
scanning by vending machines or ATMs, for example. These features include
microprint that can only be read with a magnifying glass, magnetic materials,
and fluorescent inks and fibres built into the paper that glow under ultraviolet
or infrared light.
As a further tier of security, the notes incorporate tiny amounts鈥攋ust
parts per billion鈥攐f a secret material that reacts to a high-energy
electromagnetic source such as a beam of X-rays. When notes come to the bank for
counterfeit screening, they are subjected to the usual inspections and finally
blasted with radiation that produces a characteristic signal鈥攁 unique
fluorescence spectrum, say. Every country employs this technique, says Wayne
Jackson of Note Printing Australia, the company that makes many of the world鈥檚
plastic banknotes, but only two or three people in each central bank know the
details. This ensures that no matter how good a forgery is, the bank can still
detect it. 鈥淚t鈥檚 to guard against someone who does a really great forgery, like
if the Mafia started doing it,鈥� Jackson says.
This barrage of features should make it hard for forgers to make notes good
enough to fool banks, but will they help ordinary people who are unfamiliar with
the notes? Some believe the European Central Bank has got a bit carried away and
will actually end up confusing the public. 鈥淧eople in the business have counted
at least 30 different security measures,鈥� says Rudolph van Renesse, an expert in
anti-counterfeiting technology at the Netherlands Organisation for Applied
Scientific Research in Delft. 鈥淚t鈥檚 overkill.鈥�
Counterfeiters aren鈥檛 going to make exact replicas anyway, says Derek Porter,
head of the forgery of money group at Europol鈥檚 HQ in The Hague. It鈥檚 just not
cost-effective, he says, because they only need to produce something good enough
to fool the public鈥攁nd that鈥檚 not hard. 鈥淲hen we see the counterfeits that
are accepted, it鈥檚 quite frightening,鈥� Porter says. 鈥淚鈥檝e seen black and white
photocopies filled in with felt-tip pens.鈥� Unless people know what the security
features are and how to recognise them, then they are completely useless, he
says. 鈥淵ou鈥檇 be as well producing blank pieces of paper.鈥�
So what鈥檚 the best way to make fake notes easy to spot amid a flood of
unfamiliar new currency? Novel security devices are a huge help: get the public
interested and they鈥檒l check notes for themselves. 鈥淧eople should be encouraged
to actually play with their money and become more familiar with it,鈥� says Gerry
Wilson, programme manager for security research at CSIRO, Australia鈥檚 national
research and development agency.
In the longer term, security markings should be simple and easy to recognise.
That鈥檚 precisely why some currency experts believe that plastic banknotes beat
traditional paper notes hands down.
Just 13 years after their launch in Australia, 100 billion plastic banknotes
are now printed worldwide every year. 鈥淭he prediction is that 30 per cent of
banknotes will be polymer-based by 2005,鈥� says Wilson.
The reason for this enthusiasm is that the potential range of security
features on plastic notes is mind-boggling. Cut from clear sheets of
polypropylene, plastic banknotes are coated with an opaque backing before the
other details are printed on top. Leaving holes in the opaque backing results in
clear windows in the notes. These act as simple but effective deterrents to
counterfeiters because they鈥檙e hard to reproduce, and every plastic note printed
to date includes one.
The windows also allow banks to be far more creative with their security
measures. For example, you can print a design on your notes using two inks that
look the same colour under ambient light but which look different when viewed
through a coloured filter鈥攁n effect called metamerism. Include a coloured
window elsewhere on the notes and people can easily test whether a banknote is
genuine by folding the window over onto the metameric ink design. If the note鈥檚
real, the filter shows the hidden design鈥攁 trick already used on Brazil鈥檚
10-real note.
The scope for these 鈥渟elf-authenticating鈥� banknotes is huge. Jackson says
work is already under way to make notes with two polarising windows. Place one
clear window over the other, and they go black. Rotate one of the windows
through 90 degrees and they become transparent again. Magnifying lenses can also
be built into windows to reveal microscopic details printed on the note.
Researchers at the labs of British defence technology company QinetiQ in
Malvern, Worcestershire, have their own plans for self-authenticating notes.
Keith Lewis and Gilbert Smith have developed micrometre-thick coatings that
allow only a handful of selected wavelengths of light to pass through. Each
filter is made up of a series of thin layers of titanium dioxide and silica.
Light reflects between the layers and interferes in such a way that some colours
are stripped out, while others pass through.
By designing filters in pairs, Lewis and Smith have produced colourless films
that look bright blue or red when overlaid. Lewis says that windows on polymer
notes could be fitted with two such filters that people could fold over each
other to produce the colour
(see Diagram). 鈥淲e think that this will be used on
notes of the future, in part because it鈥檚 very hard to copy, but also because
the notes themselves can be verified in a simple way by the holder,鈥� says Lewis.
Meanwhile, attempts to put windows into paper banknotes have met with limited
success, says Wilson. 鈥淭hey usually end up translucent rather than truly
迟谤补苍蝉辫补谤别苍迟.鈥�
Another advantage to plastic is that it has a distinctive feel that doesn鈥檛
change much during the life of the note. 鈥淛ust compare that with a cotton-rag
banknote that changes fairly dramatically from a crisp, stiff bill to a floppy,
creased note,鈥� says Wilson. And because the polymer films are transparent, they
could be made to act as 鈥渨aveguides鈥�, bouncing light about inside the note to
create unique patterns on the surface.FIG-23264901.jpg
鈥淐ouple this to recent developments in conducting, light-emitting and
piezoelectric polymers and you begin to appreciate the myriad ways polymers can
help us keep one step ahead of the counterfeiter,鈥� says Wilson. The Australian
experience has also shown that plastic notes last four times as long as paper
ones.
So why did the European Central Bank plump for what seems to be second best?
Partly because the decision was about more than simply picking the best
technology for the job. Choosing paper meant securing jobs in Europe, says
Jackson. With the exception of Luxembourg, printing works in every country that
signed up for the euro are contracted to print the new notes. Yet there are only
a couple of companies worldwide capable of making plastic banknotes. The
decision makes political sense, he says. 鈥淚 don鈥檛 think I would have voted for
cutting jobs in Europe if I had been in that position.鈥� More significantly,
discussions on the choice of material began in 1996, the year Australia became
the first country to completely convert to polymer banknotes. 鈥淭hey probably
thought at that time that polymer technology wasn鈥檛 mature enough,鈥� says
Jackson.
Even if the future of secure cash lies with plastic money, the paper euro is
doubtless very well defended鈥攃ertainly more so than any of the currencies
it鈥檚 replacing. But according to Lewis, rumours already abound that the second
generation of euro notes will be polymer-based. In an age when plastic is
usually seen as second best, the material could soon be worth its weight in
gold.
* * *
Banking on bugs
As forgers become more sophisticated, anti-counterfeit engineers are forced
to find bizarre new ways to stay one step ahead of them. Biological materials
could be among the next wave of security features built into banknotes. And
security technologies based on molecular or biomolecular recognition processes
such as DNA binding or antibody-antigen interactions are already under
development. But probably one of the first biological derivatives to hit the
security market will be an ink based on a protein called bacteriorhodopsin.
This protein forms a key part of the photosynthetic machinery of the
bacterium Halobacterium salinarum. Extract it and you can use
bacteriorhodopsin to create inks with unique properties, says Norbert Hampp at
the University of Marburg in Germany. Illuminating the protein with green light
changes it from purple to yellow, and blue light switches it back.
Hampp is working with a security printing company and has incorporated the
protein into ink and used it to security-mark documents. The colour-change
effect would be useful for protecting banknotes, but the protein ink also makes
documents hard to fake in the first place. The bright light from a photocopier
or scanner would change the colour of the ink, so the reproduction would look
very different.
You can also build more covert security features into the protein ink, Hampp
says. Bacteriorhodopsin is made up of a string of 248 amino acid units, many of
which can be swapped for other amino acids without affecting its colour-changing
properties. By arranging amino acids in a particular order, you can encode
information into the protein itself. The sequence can only be read by expensive
mass-spectroscopy equipment. And although the ink is currently too pricey to use
on banknotes, it should soon be cheap enough to be a viable option, Hampp
says.
The battle against counterfeiters also extends to the hardware companies who
manufacture high-resolution scanners and colour printers. They are coming under
pressure from banks to incorporate devices to make scanners incapable of copying
banknotes, or that secretly tag every document produced by a printer.
Understandably, those in the industry won鈥檛 reveal how these systems would
work. Jackson says one idea is to include security data in the dots that make up
each mark on the note. Try to scan the note and the machine detects the encoded
data and built-in software forces it to stop.
Geoff Rhoads at Digimarc Corporation in Oregon has developed another
technique for detecting when a banknote is being scanned that could even alert
the police. His idea exploits the fact that banknote designs use fine lines to
create intricate patterns. By imperceptibly varying the thickness of the lines,
you could hide information that can only be read by a scanner or photocopier.
Try to scan the banknote and software in the scanner detects the coding and
prints an image of the note, defaced with a warning message. Some copiers have
phone line connections, so an attempt to copy the note could trigger a call to
the police.