Hk3312911294

Rahul Joshi, Lokesh Gagnani / International Journal of Engineering Research and Applications
(IJERA) ISSN: 2248-9622 www.ijera.com
Vol. 3, Issue 3, May-Jun 2013, pp.1291-1294
1291 | P a g e
Improve Security & Quality of Stego Image Using Proposed LSB
Method
Rahul Joshi1
, Lokesh Gagnani2
1
PG Student,KIRC,Kalol
2
Asst Prof,KIRC (I.T Department),Kalol
Abstract
Steganography is the art of hiding the
fact that communication is taking place, by
hiding information in other information.In this
paper proposed method focus on improving
quality of stego image by increasing value of
PSNR and SNR with less number of LSB
changed compare to simple LSB method result
in better security. This paper also compares
results of proposed method with simple LSB.
I. INTRODUCTION
Steganography is the art and science of
invisible communication. This is accomplished
through hiding information in other information,
thus hiding the existence of the communicated
information. The word steganography is derived
from the Greek words “stegos” meaning “cover”
and “grafia” meaning “writing” [1] defining it as
“covered writing”. In image steganography the
information is hidden exclusively in images. Today
steganography is mostly used on computers with
digital data being the carriers and networks being
the high speed delivery channels. Steganography
differs from cryptography in the sense that where
cryptography focuses on keeping the contents of a
message secret, steganography focuses on keeping
the existence of a message secret [2].
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 [2].
The strength of steganography can thus be
amplified by combining it with cryptography.
Research in steganography has mainly been driven
by a lack of strength in cryptographic systems.
Many governments have created laws to either
limit the strength of a cryptographic system or to
prohibit it altogether [3], forcing people to study
other methods of secure information transfer.
Businesses have also started to realize the potential
of steganography in communicating trade secrets or
new product information. Avoiding communication
through well-known channels greatly reduces the
risk of information being leaked in transit [4].
Hiding information in a photograph of the
company picnic is less suspicious than
communicating an encrypted file.
II. SIMPLE LSB METHOD
Algorithm
The popular and oldest method for hiding the
message in a digital image is the LSB method. In
LSB method we hide the message in the least
significant bits (LSB’s) of pixel values of an image.
In this method binary equivalent of the secret
message is distributed among the LSBs of each
pixel.
For example data bits 01100101 are tried to hide
into an 8 bit image. According to this technique 8
consecutive pixels from top left corner of the image
are selected. The binary equivalent of those pixels
may be like this:
00100101 11101011 11001010 00100011
11111000 11101111 11001110 11100111
Now each bit of data 01100101 are copied serially
(from left hand side) to the LSB’s of equivalent
binary pattern of pixels, resulting the bit pattern
would become:
00100100 11101011 11001011 00100010
11111000 11101111 11001110 11100111
The problem with this technique is that it is very
vulnerable to attacks such as image compression
and quantization of noise.
III PROPOSED LSB METHOD
Algorithm-Hiding Operation

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.
Algorithm-Extracting Operation
In this method message bits divide into
segment using proper segment length ( like 2,4,8
etc). Create the segments in such a way that consist
equal number of bits in each segment. Select
suitable cover image enough to embed entire
message. For testing purpose I use bmp type image
of 8 bit depth. Store segments into one list called
segment list. Find all lsb of cover image and store
into one dimensional array called imagebits. Now
find the best match sequence of lsb in one segment
with sequence of imagebits. If match is found then
replace that sequence of lsb with message bits of
segment. If match is not found then insert message
bits into lsbs without overlapping the sequence of
lsb .Repeat this process for all segments.
Resultant image is called stego image. To extract
message follow algorithm for extracting operation.
IV.EXPERIMENTAL PARAMETER
a) .Number of LSB changed
This parameter count the number of lsb changed.
For better result value of this parameter keep as
minimum as possible
b). Time
This parameter use to measure time required to
hide message in image and also time required to
retrieve message from image.
c). Signal to Noise Ratio
SNR is calculate using following equation
Signal-to-noise ratio expressed in dB
d).Peak Signal to Noise Ratio
Peak signal-to-noise ratio expressed in dB
PSNR is the standard measurement used in
steganography technique in order to test the quality
of the stego images. Higher the value of PSNR
more the quality of the stego image.
V. EXPERIMENTAL RESULT
After implementation of Simple and
Proposed LSB method for lena.bmp and
rocket.bmp in Matlab (R2009a) following results
are obtained. Here both images have 8 bit depth.
Following Table shows the result of both methods
for lena.bmp

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Following Table shows the result of both methods
for rocket.bmp
Following Figures ( a to d) Shows the effect of
segment length on various parameters for
lena.bmp
(a)
(b)
(c)
(d)
Following Figures (e to h) shows the effect of
segment length on various parameters for
rocket.bmp
(e)

1294 | P a g e
(f)
( g)
(h)
Figure (a,e) shows the effect of segment length (for
2,4,5) on number of LSB changed. As length of
segment is increase number of LSB changed also
increase because probability of finding match
sequence is decrease as length of segment is
increase.
Figure (b,f) shows the effect of segment length (for
2,4,5) on SNR. As length of segment is increase
value of SNR is decrease due to number of LSB
changed increase. This is also true for rocket.bmp
Figure (c,g) shows the effect of segment length (for
2,4,5) on PSNR. As length of segment is increase
value of PSNR is decrease due to number of LSB
changed increase.
Figure (d,h) shows the effect of segment length (for
2,4,5) on Time required to hide message in image.
As length of segment is increase time required to
hide message is decrease because number of
segments is decrease .so time spend to search
match sequence is also reduced.
VI CONCLUTION
The main purpose of this method is to
decrease the number of LSB that are changed and
as a result increase the immunity of the stego-
image against the attack by human visual system
(HVS). The problem of the proposed LSB Method
is time required to hiding message that is spend
during the search to find the best matching when
using a large size stego-image. Implementation of
this method for Audio and Video Steganography
will considered as a future work.
REFERENCES
[1] Moerland, T., “Steganography and
Steganalysis”, Leiden Institute of
Advanced Computing Science,
www.liacs.nl/home/ tmoerl/privtech.pdf
[2] Wang, H & Wang, S, “Cyber warfare:
Steganography vs. Steganalysis”,
Communications of the ACM, 47:10,
October 2004
[3] Dunbar, B., “Steganographic techniques
and their use in an Open-Systems
environment”, SANS Institute, January
2002
[4] Artz, D., “Digital Steganography: Hiding
Data within Data”, IEEE Internet
Computing Journal, June 2001

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