22-11-2012, 06:18 PM
A High Capacitive and Confidentiality Based Image Steganography using Private stego-key
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INTRODUCTION
The confidentiality and data integrity are
required to protect against unauthorized access. This
has resulted in an explosive growth of the field of
information hiding. Moreover, the information hiding
technique could be used extensively on applications
of, military, commercials, anti-criminal, and so on [1].
To protect secret message from being stolen during
transmission, there are two ways to solve this
problem in general. One way is encryption, which
refers to the process of encoding secret information
in such a way that only the right person with a right
key can decode and recover the original information
successfully. Another way is steganography,
steganography literally means covered writing. Its
goal to hide the fact that communication is taking
place. In the field of steganography some
terminology has been developed. The term cover is
used to describe the original, innocent message, data,
audio, still video, and so on.
REVIEW OF RELATED WORK
The usage of a stego –key is important, because
the security of a protection system should not be
based on the secrecy of the algorithms itself, instead
of the choice of a secret key [7].The steganographer’s
job is to make the secretly hidden information
difficult to detect given the complete knowledge of
the algorithm used to embed the information except
the secret embedding key. This so called kerckhoff’s
principle is the golden rule of cryptography and is
often accepted for steganography as well [8]. Some
steganographic methods [9] [10] uses a stego-key to
embed message for achieving rudimentary security.
Beenish et al. [3] proposed technique uses predictive
position agreed between two parties as stego-key.
PROPOSED TECHNIQUE
The proposed scheme works on the spatial
domain of the cover image and employed an adaptive
number of least significant bits substitution in pixels.
Variable K-bits insertion into least significant part of
the pixel gray value is dependent on the private
stego-key K1 .Private stego-key consists of five graylevel
ranges that are selected randomly in the range
0-255. The selected key shows the five ranges of gray
levels and each range substitute different fixed
number of bits into least significant part of the 8-bit
gray value of the pixels .After making a decision of
bits insertion into different ranges. Pixel p(x, y) gray
value “g” that fall within the range Ai-Bi is changed
by embedding k-message bits of secret information
into new gray value “g’ ”. This new gray value
“g’ ”of the pixel may go beyond the range Ai-Bi that
makes problem to extract the correct information at
the receiver. Specific gray value adjustment method
is used that make the new gray value “g’ ” fall within
the range Ai-Bi. Confidently is provided by the
private stego-key and to provide integrity of the
embedded secret information, 140-bit another key K2
is used. Digital signature of the secret information
with the key is find and appended with the
information
RESULTS
To demonstrate the accomplished performance
of our proposed approach in capacity and
imperceptibility for hiding secret data in the stegoimage,
we have conducted different experiments
using different images to compare the proposed
approach with method [15].Results is considered for
image size 150x150 with 100% capacity using
different stego-keys.
Our proposed method can embeds 20% more
capacity than the method proposed in [15]. The
embedding capacity is little more than from method
[15]. Furthermore the capacity and PSNR are listed in
Tables-2. From table 2 we can see that the
performance of our proposed method is better than
the method proposed in [15]. In addition the great
benefit of our proposed method is that the embedding
process employ stego key that provide better security
and more confidentiality.
CONCLUSION AND FUTURE WORK
We have introduced an image steganographic
model and have proposed a new high-capacity
embedding/extracting module that is based on the
Variable-Size LSB substitution. In the embedding
part, based on stego-key selected from the gray value
range 0-255. We used the pixel value adjusting
method to minimize the embedding error and
adaptive 2-5 bits to embed in the pixel to maximize
average capacity per pixel. Using the proposed
method we can embedded at least 2.5 message bits in
each pixel while maintaining, the imperceptibility.