IMPLEMENTING A SUCCESSFUL DATA SECURITY ASSESSMENT
THROUGH “STEGANO-CRYPTION”
ABSTRACT
This
paper
aims
to
introduce
implementation of security of data, say,
through a network. The algorithm involves
steganocryption
which
is
actually
stegnography
combined
with
cryptography. The message to be sent is
first encrypted and then embedded into the
cover medium. In this project we are using
an image as the cover medium. The
encrypted and hidden data is kept secured
with the help of a symmetric KEY, which
the sender and the intended receiver must
possess. The resulting detection algorithm
is simple and fast.
INTRODUCTION :
In the recent times, the need for digital
communication has increased dramatically
and as a result the Internet has essentially
become the most effective and fast media
for digital communication At the same
time, data over the internet has become
susceptible to copyright infringement,
eavesdropping, hacking etc. and thereby
necessitating secret communication. As a
result a new domain dealing with security
of data has evolved and is known as
information hiding. STEGNOGRAPHY is
one such message hiding technique.
The word “Steganography” is derived
from Greek, Steganos” meaning hidden or
concealed and “graphy” means writing.
Thus, “Steganography” stands for
“concealed writing”. 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, a form of security through
obscurity.
In Histories the Greek historian Herodotus
writes of a nobleman, Histaeus, who
needed to communicate with his son-inlaw in Greece. He shaved the head of one
of his most trusted slaves and tattooed the
message onto the slave’s scalp. When the
slave’s hair grew back the slave was
dispatched with the hidden message.
Steganography and cryptography are both
ways to protect information from
unwanted parties but neither technology
alone is perfect and can be compromised.
Once the presence of hidden information is
revealed or even suspected, the purpose of
steganography is partly defeated. The
strength of steganography can thus be
amplified by combining it with
cryptography.
Cryptography: “The discipline which
embodies principles, means
and
methods for the transformation of data
in order to hide its information content,
prevent its undetected modification, or
prevent its unauthorized use”
Steganography: “A method of hiding a
secret message inside of other data.”
Essentially the difference is that, while
both hide a message, steganography is
meant to make the message invisible,
while cryptography changes the message’s
form, by means of replacement and/or
algorithm.
The
advantage
of
steganography over cryptography alone is
that messages do not attract attention to
themselves.
TERMS USED:
Stego Image: The cover image with a
secret message concealed within it is
known as the Stego image.
Cipher text: The text received as output
after cryptography that carries the secret
message.
Symmetric key: The same key being used
at the server and the client side for
encryption and decryption of the secret
text respectively.
algorithm adds redundancy to the
hidden information and then scatters it
throughout
the
image.
A
pseudorandom generator is used to
select two areas of the image (or
patches), patch A and patch B. All the
pixels in patch A is lightened while
the pixels in patch B is darkened
using a constant value for alteration.
EARLIER METHODS:
 Invisible inks prove to be a popular
medium.
 Adding spaces and "invisible"
characters to text as in HTML file.
Web browsers ignore these "extra"
spaces and lines, but revealing the
source of the web page displays the
extra characters.
 Operating systems store files,
typically resulting in unused space
that appears to be allocated to a file.
The "extra" space can be used to hide
information without showing up in the
directory.
 Appending data bytes at the end of
carrier: The secret data bytes are
appended at the end of the carrier
media such as image and the carrier
media is then compressed to its
original size to reduce the suspects of
having secret data.
 Public key steganography: This
method requires the pre-existence of a
shared secret key to designate pixels
which should be tweaked. Thus both
the sender and the receiver must have
this secret.
 Masking: Masks secret data over the
original data by changing the
luminance of particular areas. During
masking, it embeds the message
within significant bits of the cover
image. Not susceptible to lossy
techniques
because
image
manipulation does not affect the
secret message.
 Patchwork is a statistical technique
that uses redundant pattern encoding
to embed a message in an image. The
LEAST
SIGNIFICANT
ALGORITHM:
BIT
To a computer, an image is a collection of
numbers that constitute different light
intensities in different areas of the image .
All colour variations for the pixels of a 24bit image are derived from three primary
colours: red, green and blue, and each
primary colour is represented by 8 bits. In
one given pixel, there can be 256 different
quantities of red, green and blue, adding
up to more than 16-million combinations,
resulting in more than 16-million colours.
Not surprisingly the larger amount of
colours that can be displayed, the larger
the file size.
Least significant bit (LSB) insertion is a
common, simple approach to embedding
information in a cover image. The least
significant bit (in other words, the 8th bit)
of some or all of the bytes inside an image
is changed to a bit of the secret
messageFor example a grid for 3 pixels of
a 24-bit image can be as follows:
(00101101
(10100110
(11010010
00011100
11000100
10101101
11011100)
00001100)
01100011)
When the number 200, which binary
representation is 11001000, is embedded
into the least significant bits of this part of
the image, the resulting grid is as follows:
(00101101
(10100110
(11010010
00011101
11000101
10101100
11011100)
00001100)
01100011)
STEGANO-CRYPTION:
STEGANOCRYPTION= STEGANOGRAPHY + CRYPTOGRAPHY
ORIGINAL
DATA
ENCRYPTION
ORIGINAL
DATA
DECRYPTION
SHARED KEY
ENCRYPTED
DATA
CIPHER TEXT
STEGOSYSTEM
ENCODER
SEND
RECEIVE
STEGOSYSTEM
DECODER
COVER
IMAGE
CURRENT NEWS:
As steganography continues on its
evolutionary path researchers have
unearthed
new
platforms
where
steganographic techniques could be
employed to hide information seamlessly.
Such research efforts have rekindled the
research and development efforts oriented
towards steganography platforms and
steganalysis and a number of researchers
are working towards discovering new
platforms that miscreants could potentially
use to hide information. For instance,
researchers have shown that voice over
Internet protocol (VoIP) could emerge into
a popular platform for steganography
owing to its ubiquity and the difficulty in
detecting hidden information in VoIP
streams. In addition to VoIP, platforms
such as images and other multimedia
content are expected to be widely used for
concealing information. "Current research
in steganography is focused on identifying
various platforms through which one can
hide information,’ notes the analyst of this
research service. In the future, digital
camera manufacturers could implement
steganographic features as a part of camera
firmware to annotate pictures with the
photographer's copyright information.
CONCLUSION
Steganography can protect data by hiding
it but using it alone may not guarantee
total protection. It is possible that by using
a steganocryption technique, enemy
detects presence of text message in the
image file and then he/she may succeed in
extracting information from the picture,
which can be disastrous in real life
situations. This is same for plain
encryption. In this case by seeing the
meaningless appearing sequence of bits
enemy can detect that some illegal
message is being sent (unless he/she is a
fool), and we may land – up in a
problematic situation.
However, if one uses both methods, this
will lead to ‘security in depth’. The
message should first be encoded using a
strong encryption algorithm and then
embedded into a carrier.