Source: Risks-Forum Digest v14n23
Date: Tue, 5 Jan 1993 22:40:24 GMT
From: matt@wardsgi.med.yale.edu (Matt Healy)
Subject: Laserprinter Forgery

Years ago (pre-wordprocessing) I used an IBM Selectric typewriter with a
correction key.  For a lousy typist like me, this was *wonderful*.  However,
the manual warned against using a correctable (carbon film) ribbon for typing
legal documents because undetectable alterations would be too easy.

Well, recently on a Delta flight from Hartford to Atlanta one of the options
on the inflight sound system was an interview with Frank Abagnale, a reformed
forger who now advises companies on fraud prevention.

Abagnale said that output from most laserprinters and photocopiers can be
removed in a similar manner with correction tape because the toner powder,
like carbon film ribbon, only sits on the surface of the paper but does not
impregnate the fibers.  I tried it and he's right.

He said some of his clients have had checks altered in this manner.  He
suggested two solutions:

  1: use an impact printer with inked fabric ribbons

  2: there is a fixative, similar to the stuff artists
     use to protect charcoal drawings, that can be sprayed
     over the printout, making removal of toner more difficult.

Matt Healy  matt@wardsgi.med.yale.edu

PS: In the Selectric, IBM had the best keyboard I have ever used.  Why didn't
they use it for the PC?  Closest approximation I have used recently is an old
Leading Edge Model D.

       [If you wish to answer Matt's question, send mail to HIM, not to RISKS.
       By the way, the Selectric touch was fine, but the ball kept getting
       out of alignment.  I have some wonderful concrete (abstract) poetry
       generated in 1969 using just such a ball.  I had a real ball!  PGN]