Author : Khushal Srivastav
Steganography is the art
and science of writing hidden messages in such a way that no one, apart from
the sender and intended recipient, suspects the existence of the message.
Steganography differs from cryptography in the fact that Steganography does not
take a “plain” text form as input and scramble it into a “cipher” text like
cryptography does. Type of File that are used in Stegnography
Carrier File: The file that you used to hold
information that can be in the form of text or another file.
Hidden File: The file is to be inserted into the
carrier file
Types of Steganography
Linguistic Steganography
Linguistic
Steganography can be described quite simply as any form of Steganography that
uses language in the cover. A number of forms of linguistic Steganography are
covered in the next sections, but the two most basic categories are open codes
and text Semagrams. A program that takes advantage of linguistic Steganography
is NICETEXT, which uses the technique of linguistic Steganography in a very
inventive way. The goal of NICETEXT is to provide a program that can transform
cipher text (encrypted text) into text that looks like natural language, while
still providing a cover for the original cipher text. An added benefit of this
type of program is that it can be applied to many different languages.
Text Semagrams
Text
Semagrams work with graphical modifications of the text, such as type-spacing
and offsetting.
They
concern details that are tiny, but nonetheless visible. Certain methods work
without text as well. These are called real Semagrams.
Technical Steganography
Technical
Steganography is a little broader in scope since it doesn’t necessarily deal with
the written word, even though it communicates information. Technical
Steganography is the method of Steganography where a tool, device, or method is
used to conceal the message. Let’s have a look at some technical Steganography
methods.
Embedding Methods
The
technical challenges of data hiding are formidable. Any “holes” to fill with
data in a host File, either statistical or perceptual, are likely targets for
removal by lossy compression. The key to successful data hiding is the finding
of holes that are not suitable for exploitation by compression algorithms.
Least Significant Bit
Least
Significant Bit (LSB) is the substitution method of Steganography where the
right-most bit in a binary notation, the bit with the least impact on the
binary data, is replaced with a bit from the embedded message. This method
provides “security through obscurity,” a technique that can be rendered useless
if an attacker knows the technique is being used.