International Journal of Engineering Trends and Technology (IJETT) – Volume 13 Number 5 – Jul 2014
Enhanced Steganography Algorithm to
Improve Security by using Vigenere
Encryption and First Component Alteration
Technique
Deeksha Bharti #1, Dr.Archana Kumar*2
#
1 M.tech Student , #2 Associate Prof. ,
Dept. of CSE ,Delhi Institute of Technology and Management,
DCRUST ,Murthal ,Haryana
Abstract –Steganography is the art of hiding
information and an effort to conceal the existence of
the embedded information. In recent years many
steganography methods have been challenge by
steganalysis . Steganalysis algorithm which detects
the stego -message by the static analysis of pixel
values [1]. In the proposed method, the secret
message is encoded by using vigenere encryption
method which guarantees the protection of hidden
message. Then hiding the secret text in an image by
using first component alteration technique .In this
technique, 8 bits of blue components are replaced
with secret data bits , then that image can be hidden
in cover image in non sequential pixel by using
variable hope value power of 2 [2,4,8,16].The
Proposed method aim not only to provide improved
security problems of simple LSB method but also the
increased visual quality of stegoimage.
Keywords- steganography , vigenere encryption , LSB
embedding , extraction , first component alteration
technique.
I.INTRODUCTION
Data protection and security of the personal
information have become a critical issue in the
digital world. Therefore, the demand of having a
protected method to transfer the confidential data is
dramatically increasing. Steganography is the art of
passing information through original files in a
manner that the existence of the message is
unknown. The term steganography is arrived from
Greek word means, “Covered Writing” [1]. In
contrast to cryptography which make data
unreadable for a third party by implying some
encryption methods, steganography emphasize on
hiding the existence of message inside another data
in such a way that nobody can detect it. In image
steganography the image used to camouflage the
secret data is called the cover-image while the
cover-image with the secret data embedded in it is
called the stego-image[3].
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II. THE CONVENTIONAL
STEGANOGRAPHY AND
CRYPTOGRAPHY
The Least Significant Bit (LSB) insertion is the
most common spatial domain technique, which
consecutively replaces the least significant bit of
cover image with the message bits. This method
exploits the natural weakness of Human Visual
System (HVS) in recognizing the slight difference
of colours . The LSB method changes some or all
the 8th bit of image’s data so that the image’s
alteration is not perceptible for any human eyes. In
like manner, when using a colour image the LSB of
each of the red, green and blue components can be
used. Therefore, the potential capacity for hiding
secret data in a colour image is triple of the same
image size in the grayscale mode.[4]An immediate
concern is to find out best possible attacks to carry
out steganalysis, and simultaneously, finding out
techniques to strengthen existing steganography
techniques
against
popular
attacks
like
steganalysis.
A.Cryptography
Cryptography encodes information in such a
way that nobody can read it, except the person who
holds the key. More advanced crypto techniques
ensure that the information being transmitted has
not been modified in transit. There is some
difference in cryptography and steganography, in
cryptography the hidden message is always visible,
because information is in plain text form but in
steganography hidden message is invisible.
B. Steganalysis
Steganalysis is "the process of detecting
steganography by looking at variances between bit
patterns and unusually large file sizes". [1]The goal
of steganalysis is to identify suspected information
streams, determine whether or not they have hidden
messages encoded into them, and, if
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International Journal of Engineering Trends and Technology (IJETT) – Volume 13 Number 5 – Jul 2014
possible, recover the hidden information. The
challenge of steganalysis is that:
1. The suspect information stream, such as a
signal or a file, may or may not have hidden data
encoded into them.
2. The hidden data, if any, may have been
encrypted before being inserted into the signal or
file.
3. Some of the suspect signal or file may have
noise or irrelevant data encoded into them (which
can make analysis very time consuming).
III. MATERIALS AND METHOD USED
A. Vigenere Encryption
In a Caesar cipher, each letter of the alphabet is
shifted along some number of places; for example,
in a Caesar cipher of shift 3, A would become D, B
would become E, Y would become B and so on.
The Vigenère cipher consists of several Caesar
ciphers in sequence with different shift values.
To encrypt, a table of alphabets can be used,
termed a tabula recta, Vigenère square, or Vigenère
table. It consists of the alphabet written out 26
times in different rows, each alphabet shifted
cyclically to the left compared to the previous
alphabet, corresponding to the 26 possible Caesar
ciphers. At different points in the encryption
process, the cipher uses a different alphabet from
one of the rows. The alphabet used at each point
depends on a repeating keyword.
For example, suppose that the plaintext to be
encrypted is:
ATTACKATDAWN
The person sending the message chooses a
keyword and repeats it until it matches the length
of the plaintext, for example, the keyword
"LEMON":
LEMONLEMONLE
Each row starts with a key letter. The remainder
of the row holds the letters A to Z (in shifted
order). Although there are 26 key rows shown, you
will only use as many keys (different alphabets) as
there are unique letters in the key string, here just 5
keys, {L, E, M, O, N}. For successive letters of the
message, we are going to take successive letters of
the key string, and encipher each message letter
using its corresponding key row. Choose the next
letter of the key, go along that row to find the
column heading that matches the message
character; the letter at the intersection of [key-row,
msg-col] is the enciphered letter
For example, the first letter of the plaintext, A, is
paired with L, the first letter of the key. So use row
L and column A of the Vigenère square, namely L.
Similarly, for the second letter of the plaintext, the
second letter of the key is used; the letter at row E
and column T is X. The rest of the plaintext is
enciphered in a similar fashion:
Plaintext: ATTACKATDAWN
Key: LEMONLEMONLE
Ciphertext: LXFOPVEFRNHR
Decryption is performed by going to the row in
the table corresponding to the key, finding the
position of the ciphertext letter in this row, and
then using the column's label as the plaintext. For
example, in row L (from LEMON), the ciphertext L
appears in column A, which is the first plaintext
letter. Next we go to row E (from LEMON), locate
the ciphertext X which is found in column T, thus T
is the second plaintext letter
B. First Component Alteration technique
A new image steganography scheme based on
first component Alteration technique. In a
computer, images are represented as arrays of
values. These values represent the intensities of the
three colors R (Red), G (Green) and B (Blue),
where a value for each of three colors describes a
pixel. Each pixel is combination of three
components(R,G and B). In this scheme, the bits of
first component (blue component) of pixels of
image have been replaced with data bits. Blue
channel is selected because a research was
conducted by Hecht, which reveals that the visual
perception of intensely blue objects is less distinct
that the perception of objects of red and green.
For example, suppose one can hide a message in
three pixels of an image (24-bit colors). Suppose
the original 3 pixels are:
(00100111 11101001 11001000)
(00100111 11001000 11101001)
(11001000 00100111 11101001)
A steganographic program could hide the letter
"A" which has a position 65 into ASCII character
set and have a binary representation"01000001", by
altering the blue channel bits of pixels.
(01000001 11101001 11001000 )
(00100111 11001000 11101000 )
(11001000 00100111 11101001)
IV. PROPOSED STEGANOGRAPHY
METHOD
In this section , the proposed scheme in which at
initial step vigenere encryption is used to encrypt
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International Journal of Engineering Trends and Technology (IJETT) – Volume 13 Number 5 – Jul 2014
the text message ,then first component alteration
technique is used to hide the encrypted message
inside an image . In this technique, 8 bits of blue
components in a pixel are replaced with secret data
bits ,in second step ,then that image can be hidden
in cover image in non sequential pixel by using
variable hope value power of 2 [2,4,8,16] .[5]
A. Proposed Embedding Process
This phase includes all the activities that must be
carried out to hide and protect the secret data inside
the cover image. The sender uses some algorithms
to encode and then embeds the bit stream into the
image.
Select secret data
Encrypt secret data by
vigenere table
changed and also in what order they will be altered
with the secret data .In this by using first
component alteration technique the data is
embedded into an image results into stego image1 .

2nd phase Embedding (image into cover
image) - In this phase the stego image is embedded
into a cover image non sequentially by variable
hope value power of 2 [2,4,8,16,32 ] results into
stego image 2.
B. Proposed Extraction Process
At the receiver site, extraction is done. In 1st
phase extracting algorithm the secret image will be
recovered from cover image . In 2nd phase of
extraction , the bits of secret message are obtained
by extracting data bits from blue component ,
finally then decrypt the secret data by using
vigenere table , the plain message will be revealed.
3.3. MULTI-LAYERED EMBEDDING AND
DECODING
1st phase Embedding secret data in
image by first component alteration
technique
2nd phase Embedding stego image non
sequentially in cover image by variable hope
value power of 2 [2,4,8,16,32 ]
To attain higher security, a sender embed secret
data into multiple layers of cover-image. This
multi layering of cover images creates the stealth
camouflage. In the encoding process of
multilayered encoding first component alteration
technique is used in first layer in which secret data
is embedded into an image results stego-image1 .
Then in 2nd layer of embedding stego-image1 is
embedded into stego-image2 non sequentially by
variable hope value power of 2 (2, 4, 8, 16, 32 ).
The number of layers embedded is only known by
the sender preventing others from retrieving the
secret data. Figure 2 shows the process:
Stego image
Fig.1
Proposed Embedding Technique

Encryption - In the first step of the
embedding phase, the plain text will be encrypted
using the Vigenere table (table in [8]) . There are
several encryption methods that can be applied to
encrypt the data, but in this situation, we need a
method that does not produce a cipher text longer
than the plain text. Furthermore, among the desired
encryption methods, Vigenere table, which is a
symmetric encryption technique and maps each
input character into exactly one character for
output, is more secure than similar methods[4]. The
biggest advantage of Vigenere table over the other
symmetric encryption methods is that based on the
specified secret key, it produces different outputs
for a certain input character.

1st phase Embedding (text into image) The embedding algorithm is the most prominent
part of the steganographic methods. In fact, it
defines which pixels of the image should be
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Fig. 2 Multi-layered encoding
When the sender conveys the secret message to a
receiver, the sender needs to notify the receiver of
the actual layers of cover-images that have been
embedded. Only then can the receiver decode the
cover-images layer by layer, obtain the original
secret data and saving what is produced. Figure 3
shows the secret data decoded from multiple layers
of cover-images.
Fig.3 Multi- layered decoding
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V. RESULTS AND DISCUSSIONS
The proposed method is implemented by using
MATLAB and images of lena and baboon , which
are illustrated in figure 4 .
PSNR
100
50
0
LSB
Baboon
Improved
LSB
Lena
Fig.5 shows the difference between the PSNR of
previous work and improved algorithm
Fig.4 Standard photos of lena and baboon
A.
FCAT
STEGO IMAGE DISTORTION ANALYSIS
Peak Signal-to-Noise Ratio (PSNR) is used to
measure the quality of the stego-image that
produced by applying the algorithm . PSNR is the
most popular metric to measure the distortion in an
original image and a reconstructed image. A
greater value for PSNR quality metric indicates a
lower degree of distortion for generated image .
Comparative result in table 1 shown that PSNR
will increase in proposed work so there is no big
difference in the visibile quality of original image
and stego image . This shows that visual
differences will appear indistinguishable for human
visual senses . As results are shown below ;
In order to identify the PSNR of a stego- image
the Mean Square Error ( MSE ) has to be measured
:
Where m and n are the number of rows and
number of columns of cover image respectively ,
ƒ(i, j ) is the pixel value from cover image , g( i,j )
is the pixel from stego image and L is peak signal
value of the cover image .
Fig 6 Output of 1st phase embedding
PSNR =10 × log10( L2 /MSE) dB
If PSNR falls below 30 dB indicates a fairly low
quality image which is most likely caused by
distortion during embedding process . A high
quality stego-image should measure 40 dB or
higher .However , by increasing amount of data in
image a significant fall will appear in the PSNR
value .
Comparative study of previous method and
improved LSB substitution method is shown
below:
Lena
Image
PSNR
( dB)
LSB
26.08
First
Component
alteration
Technique
46.11
Improve
d
LSB
68.10
Fig 7. Output of 2nd phase embedding
VI.
Table 1 comparative study of previous work with
proposed work .
Experimental result had shown the strength of
this technique . The PSNR of stego- image is
calculated and compared with previous work .
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SECURITY OF PROPOSED
SYSTEM
The goal of Steganography is to avoid drawing
suspicion to the transmission of hidden
information, if suspicion is raised, then
Steganography security is defected. On other hand
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the aim of cryptography is to convert intelligible
information to unintelligible form, difficult for the
third parties which do not have the key. The
proposed system achieves the union goal of
security for the below reasons:
large capacity of the hidden secret data and to
maintain a good visual quality of stego-image .
1) The results of proposed system stego-object is
an image, this image is transmitted alone without
the original image, this point enhance the security
of system because there is little ability of matching
between the original cover image and the stegoobject.
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2) The proposed system is build of muti-layer
security, consequently even if the original copy of
the stego-object is available, the intruder attacked
by the second layer of security which is the
encryption of the text embedded then he should
analyze the cipher text which is difficult to be
analyzed.
VII.
CONCLUSION
In this paper , enhanced LSB substitution
process for data hiding is proposed . Vigenere
encryption used for encoding the confidential
information , First component alteration technique
used in 1st phase embedding ie. Text into an image
.In 2nd phase embedding ie. Image into an image ,
data is embedded non sequentially by using
variable hope value power of 2 [ 2,4,8,16 ]. As it
was expected theoretically, the satisfactory results
were achieved when method was implemented.
Experimental result show the effectiveness of
proposed method .The results obtained also show
significant improvement in the PSNR than the
previous works , the possibility of extracting the
content of hidden data reduces significantly , when
private message becomes encrypted.
Finally a good balance between the security
and image quality is achieved .
VIII.
FUTURE WORK
In this study , we tried out to increase the
security level of the previous works like in simple
lsb and first component alteration technique.
However , many suggestions can be given to
enhance the work of the proposed system they
are:1)
By using compression with the proposed
system , capacity of payload can be increased .
2)
Enhance the method in terms of integrity
.That means whenever the secret data being
modified within the transmission channel the
receiver must realize that is a fake message .
REFERENCES
3)
This proposed method can be improved by
using with neural network based method to provide
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