1. Introduction
Steganography is the art, science, or practice in which
messages, images, or files are hidden inside other messages,
images, or files. The concept of steganography is
not a new one; it dates back many millennia when messages
used to be hidden on things of everyday use such
as watermarks on letters, carvings on bottom sides of
tables, and other objects. The more recent use of this
concept emerged with the dawn of the digital world.
Experiments have shown that data can be hidden in many
ways inside different types of digital files. The main
benefit of steganography is that the payload is not expected
by the investigators who get to examine the computer
data. The person sending the hidden data and the
person meant to receive the data are the only ones who
know about it; but to everyone else, the object containing
the hidden data just seems like an everyday normal object.
A classification of information hiding techniques is
described in