July 19, 2002

Signals in the noise: Peter Wayner's new book on steganography

Author: JT Smith

- By Joab Jackson -

When Peter Wayner wrote a book on the practice of steganography in 1996, the
term seemed so arcane, so daunting, that his publisher insisted he not use
that word in the title.
That changed in the days after Sept. 11, however. Among the many rumors
floating around after the attacks, one held that Osama Bin Laden's minions
communicated with one another via messages embedded in digital photographs
that they sent around the Internet. Or something along those lines. The story
was never verified, Wayner says, although the idea brought to light the
little-known and ancient art of steganography. As luck would have it, Wayner
was updating Disappearing Cryptography (the 1996 version was subtitled
Being and Nothingness on the Net) at the time.

Steganography has long been a sort of lonely stepchild to encryption. At its
simplest, encryption is the art of scrambling a written message so that the
resulting seemingly random collection of characters cannot be easily
deciphered by another party. Steganography is the art of hiding of a message
within another message, such that a passer-by is unaware of the concealed
meaning.

Digital photographs are a particularly good medium for steganography.
"Digitized photos or sounds are represented by numbers that encode the
intensity at a particular moment in space and/or time," Wayner writes in the
new edition of his book Disappearing
Cryptography -- Information Hiding: Steganography and Watermarking
.

Even a small digital photograph can hide a lot of information.
Disappearing Cryptography shows a before-and-after series of seemingly
identical photographs of bridges, city skylines, and deserts that were
encoded with messages. It takes very careful work to find the difference, if
it can be seen at all. Many of the photographs contain the text of an entire
chapter of the book itself, yet the most careful observer will only see a bit
of loss in the picture's color as the binary digits that represent those
colors are intermingled with the binary digits carrying the words.

"We want to believe that if there's anything real and true in the world, it's
the meaning of numbers like zero and one," Wayner says in an email
interview. "But after steganography, even bits can offer multiple readings
and misreadings."

After reading the newly released second edition of Disappearing
Cryptography
, it's hard not to look around for hidden messages that may
be buried in handbills, menus, Billboard's album charts. Everything
becomes a potential carrier for surreptitious information. Even Wayner's book
may be suspect, though he insists this isn't the case.

"For the record, I didn't really put any [hidden codes of my own] in the
book," he says. "If anything, the math and the metaphors are tricky enough
the first time."

Steganography is hardly a computer-age phenomenon. As another
cryptography-obsessed writer, Simon Singh, pointed out in his 1999 history of
encryption, The
Code Book
, the practice dates back at least a few centuries, when
Chinese messengers swallowed secret notes sealed in wax to carry to their
intended recipients. More recently, James Bamford's profile of the National
Security Agency, The
Puzzle Palace
, tells of how gangsters used to communicate with one
another by the number of shirts they sent to Las Vegas to be dry cleaned. The
basic idea behind steganography is the same -- finding ways to transport data
within other forms.

Wayner, 38, has long been one of the most respected writers on computer
technology, having done stints as a technology correspondent for The New York Times and the newsstand
version of Byte magazine. He has
also written a number of books such as 1999's Compression
Algorithms for Real Programmers
and the also newly released Translucent
Databases
.

Judging from a recent lunch interview, Wayner seems uninterested in the usual
book-promotion rigamarole. When asked how he became so entranced with
steganography, Wayner says only that it started when a friend asked if it was
possible to hide one message within another. Asked about where to get more
information about Disappearing Cryptography's rerelease, he randomly
muses about Congress and the entertainment industry's ham-fisted attempts to
utilize encryption as a method of copyright control. A Princeton-trained
mathematician, Wayner loathes the idea of outlawing the act of
circumnavigating digital copyright-protection schemes. In the heart of such
legislation, he writes in the book, is an attempt "add security by
prohibiting knowledge."

The field of computer-technology writing teems with writers who lose
themselves and their readers in thickets of directionless arcana and
technical terms. Wayner is one of those rare tech scribes who can get the
details right and shape a story. While much of Disappearing
Cryptography
gets into the nitty-gritty of writing and using computer
programs to hide information, it also revels in the philosophical and
cultural underpinnings of its subject matter.

In the book, Wayner asks whether this tool can be used for good or for evil. The answer is, of course, both. He admits that steganography holds obvious allure for the child pornographers and terrorists of the world. But he also
notes that the technique can be used by freedom fighters to safely
communicate beneath the radar of corrupt governments, by law enforcement to
pass messages back and forth to undercover agents, and by whistle-blowers to
pass on secrets about corporate malfeasance.

Steganography can even be fun. Wayner's Web
site
features a section on how to use a random collection of just about
any object -- a shopping list, a tally of favorite disco records -- as a way to
embed secret messages.

"Life often reduces to formulas," Wayner writes in the book. Formulas
identify the redundancies, or the noise, of daily life that falls just under
our perceptions, then simplifies them. Steganography exploits those
redundancies, most often without us ever noticing.

With thinking like that, it's easy to imagine that Wayner sees patterns
everywhere. Does he look for hidden messages in the world around him? He
shrugs it off.

"In most cases, the best algorithms are good enough to be virtually
unbreakable. So I don't try to look for messages encoded with the best
algorithms," he emails. "But vanity license plates can be a real game."

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