Introduction to Steganography:
Hiding in Plain Sight
Steganography, the science of hiding secret
messages within publicly accessible material, is an ancient
science. One of the first accounts of steganography in action
dates back to the Greek historian Herodotus. In the fifth
century BCE he documented the story of Demeratus, who struggled
to find a way of alerting Sparta that the Persian Great
King Xerxes was gearing up to invade Greece. Knowing that
any overt message would be intercepted easily by the Persians,
he scraped off the wax surface of a wooden writing tablet
and scratched his warning into the underlying wood. Demeratus
then re-coated the tablet with a fresh layer of wax, thus
allowing the apparently blank writing tablet to be carried
off to Sparta without arousing suspicion.
In the modern world, steganography simply
takes one piece of information and hides it within another
electronically. Computer files (images, sounds recordings,
even disks) contain unused or insignificant areas of data.
Steganography takes advantage of these areas, replacing
them with information (encrypted mail, for instance). The
files can then be exchanged without anyone knowing what
really lies inside of them. An image of the space shuttle
landing might contain a private letter to a friend. A recording
of a short sentence might contain your company's plans for
a secret new product. Steganography can also be used to
place a hidden "trademark" in images, music, and
software, a technique referred to as watermarking.
The issues that surround steganography are
quite similar to the controversy that surrounded and still
continues to surround another similar field, that of publicly
available strong encryption. The encryption debate has revolved
around issues of industrial competitiveness, personal privacy,
and the interests of national security and law enforcement.
The main reason we chose to examine this
one particular area was linked to our mutual fascination
with encryption and security issues in general. Also, the
large amount of media attention it has received in the recent
past in conjunction with 9/11 has caused much concern in
the uninformed public.
The main goal of this project was to investigate
the history and various approaches to steganography and
see how hard it would be to create a simple, first generation
electronic stegonographic program that allows the user to
embed text in an image as well as to investigate the legal
and social issues surrounding this topic.
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