Steganography is derived from the Greek for covered writing and essentially means to hide
in plain sight. As defined by Cachin  steganography is the art and science of
communicating in such a way that the presence of a message cannot be detected. Simple
steganographic techniques have been in use for hundreds of years, but with the increasing
use of files in an electronic format new techniques for information hiding have become
This document will examine some early examples of steganography and the general
principles behind its usage. We will then look at why it has become such an important issue in
recent years. There will then be a discussion of some specific techniques for hiding
information in a variety of files and the attacks that may be used to bypass steganography.
Figure 1 shows how information hiding can be broken down into different areas.
Steganography can be used to hide a message intended for later retrieval by a specific
individual or group. In this case the aim is to prevent the message being detected by any
The other major area of steganography is copyright marking, where the message to be
inserted is used to assert copyright over a document. This can be further divided into
watermarking and fingerprinting which will be discussed later.