		Taliban

Osama bin Laden and others "are hiding maps and
photographs of terrorist targets and posting
instructions for terrorist activities on sports chat
rooms, pornographic bulletin boards and other
websites," US and foreign officials say. The
technique, known as steganography, is the practice of
embedding secret messages in other messages -- in a
way that prevents an observer from learning that
anything unusual is taking place. Encryption, by
contrast, relies on ciphers or codes to scramble a
message. 

The practice of steganography has a distinguished
history: The Greek historian Herodotus describes how
one of his cunning countrymen sent a secret message
warning of an invasion by scrawling it on the wood
underneath a wax tablet. To casual observers, the
tablet appeared blank. 

Modern steganographers have far-more-powerful tools.
Software like White Noise Storm and S-Tools allow a
paranoid sender to embed messages in digitized
information, typically audio, video or still image
files, that are sent to a recipient. 

The software usually works by storing information in
the least significant bits of a digitized file --
those bits can be changed in ways that aren't dramatic
enough for a human eye or ear to detect. One program,
called snow, hides a message by adding extra
whitespace at the end of each line of a text file or
e-mail message. Perhaps the strangest example of
steganography is a program called Spam Mimic, based on
a set of rules, called a mimic engine, by Disappearing
Cryptography author Peter Wayner. It encodes your
message into -- no kidding -- what looks just like
your typical, quickly deleted spam message. -- USA Today 

Arnab Majumdar, Nitin Chopra.