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(IJCSIS) International Journal of Computer Science and Information Security,
Vol. 9, No. 5, May 2011
A Novel Steganographic Methodology For
Secure Transmission Of Images
B.V.Ramadevi*D.LalithaBhaskari*P.S.Avadhani*
Research ScholarAssociate ProfessorProfessor
bvramadevi@yahoo.comlalithabhaskari@yahoo.co.inpsavadhani@yahoo.com
*Department of Computer Science & Systems Engineering
AUCE(A), Andhra University,Visakhapatnam
Abstract : information which is to be embedded is called
In recent days steganographictechniques the stego message. Today steganography has got
have gained a lot of significance in many of the many differentways to hide information like
security applications. In this paper a two layered images, audio, video
secure methodology for transmitting multimedia etc.Infactsteganography,cryptography,watermar
data is proposed and implemented. In the first king are all different branches of information
layer,encoding based compression of the hiding.Information hiding also often termed as
message to be hidden is done based on data hiding or multimedia data hiding is a term
G delization and Alphabetic coding(AC). In the covering a wide range of problems beyond
second layera steganographic approach is embedding messages in content. The term hiding
adopted for embedding of the encoded text into can refer to either making the information
the cover image under frequency domain and the perceptible or keeping the existence of
obtained stego image is transmitted securely information secret. Compared with text or binary
using a novel encryption and decryption data, multimedia data often has high
methods. redundancy, large volumes and real-time
Keywords: Alphabetic Coding, Cover image, operations. All these properties require that
Encryption, Decryption,G delization,stego multimedia data should be compressed,
image. encrypted and securely transmitted for the
required applications. During the past decades,
1. Introduction various multimedia encryption algorithms have
been proposed and studied.They can be
Steganography is a modern and classified into three types which are image
dynamically developing part of information encryption, audio encryption, and video
security whichprotects information by its hiding encryption. Generally, for different content,
techniques. Technically speaking, steganography different encryption algorithms should be
is a covert communication technology, which adopted[1].In this paper a novel image encoding
allows secret information to be embedded into a based on G delization[2],compression based on
cover/host message without significantly alphabetic coding[2],embedding the data into the
damaging the content of the cover message. The cover image using a steganographic method
message usually will be an image and the secret termed as middle band coefficient exchange
132 http://sites.google.com/site/ijcsis/
ISSN 1947-5500
(IJCSIS) International Journal of Computer Science and Information Security,
Vol. 9, No. 5, May 2011
algorithm[3] and then secure transmission of the spatial domain[4] where the intensity
data using a methodology based on encryption values(pixels) of the image are manipulated and
and decryption[4]are proposed and presented. data is hidden in the intensity values of the
images. The second method is frequency domain
where the frequency components of the digital
2. Basic Concepts images are considered[5,6]. The secret data is
In this paper, the proposed methodology is embedded into the frequency components of the
divided intotwolayers(modules)for embedding image. It is observed that spatial domain
and securely transmitting the multimedia data. manipulations are easy when compared to
The first layer consists of converting(encoding) frequency domain, yet frequency domain
the secret image into string of Gödel Number provides more security when compared to
spatial domain techniques. So in this work,
Sequence throughGödelization, compressing the
frequency domain is chosen as the media and
encoded string using alphabetic coding discrete cosine transforms(DCT)[7] are
andembedding the encoded compressed considered. After embedding the data into the
stringinto the cover image using middle band cover image, a key(k) and a stego image is
coefficient exchange method[3] under frequency obtained which is given as input to the second
domain.In the second layer, encryption and layer. In the second layer, the obtained Key and
decryption techniquesare implemented for the stego image are encrypted and transmitted.
At the decoding end, the decoder decrypts the
secure transmission of the data. In this section a
stego image with his private key.
brief description of the definitions and the
concepts are presented. 3. Encryption and Decryption
In the first layer, the secret image which With the continuing development of both
is to be transmitted securely is converted into computer and Internet technology, multimedia
Gödel Number Sequence(GNS) through the data (images, videos, audios, etc.) is being used
concept of Gödelization[2]. According to it,the more and more widely, in applications such as
intensity values at a point f(x,y) in the image are video conferencing, broadcasting, education,
transformed into thepower of its primes. commerce, politics etc., and so the security
Consider a pixel value 39 which can be concerns are also increasing. To maintain
factorized as 31×131. So the Gödel number security, multimedia data should be protected
sequence of 39 = GN (0,1,0,0,0,1). The before transmission or distribution. The typical
sequence 0,1,0,0,0,1 can be encoded as 31×131 protection method is the encryption technique
as GN(0)= 2,GN(1)=3,GN(2)=5 and so on.After [9] which transforms the data from the original
converting each and every pixel into the form into an unintelligible form. Until now,
corresponding GNS, alphabetic compression various data encryption algorithms have been
technique(AC)[2] is applied to compress the proposed and widely used, such as AES, RSA,
GNS. According to AC, if the GNS has a or IDEA [9,10], most of which are used in text
sequence of more 0’s and 1’s, we represent 0’s or binary data. It is difficult to use them directly
with ‘A’, 1’s with ‘B’, 2’s with ‘C’ and so on. If in multimedia data, for multimedia data are
we encounter more than 3 same characters then, often of high redundancy, of large volumes and
the number of occurrences are representedfirst require real-time interactions, such as
followed by the character.After applying AC, displaying, cutting, copying, bit rate conversion,
there is a considerable amount of compression etc. So in this paper, the multimedia data(the
achieved.The obtained encoded compressed secret image) is encoded and compressed using
string is embedded into the cover image using Gödelization and alphabetic coding as explained
middle band coefficient exchange[2] method in the previous section.This encoded compressed
under frequency domain.According to literature string is embedded into the cover image under
survey, embedding of secret data into the digital frequency domain using middle band coefficient
images can be done in two domains. One is exchange method[10] to obtain a key and a stego
133 http://sites.google.com/site/ijcsis/
ISSN 1947-5500
(IJCSIS) International Journal of Computer Science and Information Security,
Vol. 9, No. 5, May 2011
image. The key and stego image combined Number string(GNS) using Gödelization
together are encrypted and transmitted. At the technique,later the encoded string is compressed
decoding end, it is decrypted using the decoder’s using AC technique.This encoded compressed
private key. The encryption and decryption
string is embedded into the cover image using
models are shown below in fig 1 and 2
respectively. middle band frequency exchange method in the
frequency domain.The output obtained after
embedding the data is a key and a stego
image.This provides the first layer of
Message Cipher security.The obtained key and the stego image is
now encrypted and decrypted.In this model,
(M) Encryption text MD5 is used for hashing,IDEA is used for the
encryption process. This provides second layer
of security and the data is transmitted. At the
decoder end the data is decrypted so as to obtain
themessage which is the key (k) and the image
data(M) which is obtained during embedding
under frequency domain.This data is decoded
with the key, then reverse Gödelization is used
Fig 1. Scheme for Encryption to obtain GNS, upon which reverse alphabetic
coding is applied to obtain the image data
whichis reconstructed to obtain the secret image.
Here the stego image and the key generated
are given as input to the encryption
algorithm. The cipher text is given as input
to the decoder which decodes the cipher text
along with the receiver’s private key.The
decoding process is as shown below. Encryption
Algorithm(E)
Secret
image
Cipher text Messa Gödelization ||
Decryption
ge(M) Stego image
Gödel Number
String (GNS)
Fig. 2Scheme for decryption Key
Alphabetic
( K)
4. Proposed Methodology coding(AC)
Stego
The proposed methodology provides Encoded Embedder
compressed
two layered security when compared to the string
traditional methods.The whole scheme of the
proposed methodology can be viewed as shown
below in figures3 and 4. The secret image(data)
which is to be hidden is encoded into Gödel
134 http://sites.google.com/site/ijcsis/
ISSN 1947-5500
(IJCSIS) International Journal of Computer Science and Information Security,
Vol. 9, No. 5, May 2011
Fig 3. Scheme of proposed method at the
encryption side
The decryption side scenario is given below in
fig 4.After decoding image can be reconstructed
at the receiver’s side from the obtained data.
Fig 4.Scheme of proposed method at the
Decryption
decryption side.
Algorithm (D)
5. Results
The proposed model is being implemented using
Matlab 7.0 and JAVA. The results proved to be
K more secure and satisfactory. Some test cases
M are provided here.
Sender’s side encryption:
Stego
Decoder
Secret
Image
Encoded
compress
string
Reverse Receiver’s side decryption:
Reverse AC Gödelization
GNS
135 http://sites.google.com/site/ijcsis/
ISSN 1947-5500
(IJCSIS) International Journal of Computer Science and Information Security,
Vol. 9, No. 5, May 2011
that more data payload capacity can be achieved
which sometimes is necessary in some
applications.
7. References:
[1] S. Lian, J. Sun, D. Zhang, and Z. Wang, “A
Selective Image Encryption Scheme Based on
JPEG2000Codec”,2004,Pacific-Rim Conference
on Multimedia (PCM2004), Lecture Notes in
Computer Science, Vol. 3332,pp 65–72.
[2]B.V.Rama Devi, P.PrapoornaRoja,
D.LalithaBhaskari,P.S.Avadhani, “A New
Encryption Method for Secure Transmission of
6.Conclusions& Future Work
Images”, 2010, International Journal of
Thus by implementing the proposed model it is Computer Science and Engineering
(IJCSE),Vol.02,No.09, pp2801-2804.
observed that not only the data payload capacity
has increased but security is also enhanced when [3]BNeil F. Johnson., Stefan C.Katzenbeisser,
compared to other methods.By using “Chapter 3: A Survey of Steganographic
Techniques”, Arctech House, London, 2000.
G delization data is being encoded which is in
turn compressed so as to increase the data [4]P.S.Avadhani, D.LalithaBhaskari, “A Blind
payload capacity. This data is embedded into the Scheme Watermarking Technique Using
GÖdelization Technique for RGB images under
cover image using middle band frequency spatial domain”, International Conference on i-
exchange methods under frequency domain warfare (ICIW-2010), Dayton,USA, 8th -9th
April 2010, pp 373-377.
which is proved to be secure.This data is again
transmitted using a novel encryption/decryption [5]El-Gayyar, Joachim von zurGathen,
“Watermarking Techniques Spatial Domain”,
model and data is retrieved at the decoder end. It Digital Rights Seminar, University of Bonn,
is also observed that, after embedding the data Germany, May 2006.
into the cover image there is no perceptual [6] D. Tzovaras, N. Karagiannis, M. G. Strintzis,
difference between the cover image and the “Robust image watermarking in the subband or
discrete cosine transform domain”, 9th
stegoimage which satisfies the property of a European Signal ProcessingConference
blind steganographic scheme. In a blind scheme (EUSIPCO’98), Greece, 8–11, Sept. 1998, pp
2285–2288.
the cover image is not required at the decoder’s
end and the implementation results are [7]Bret Dunbar, “A detailed lookat
Steganographic Techniques and their use in an
satisfactory.As future enhancement, the same Open-Systems Environment”, The Information
technique can be enhanced for RGB images so Security Reading Room, SANS Institute, 2002.
136 http://sites.google.com/site/ijcsis/
ISSN 1947-5500
(IJCSIS) International Journal of Computer Science and Information Security,
Vol. 9, No. 5, May 2011
[8]http://www.mishmash.com/fredspgp/pgp.htm
[9]S. A. Vanstone, A. J. Menezes, and P. C.
Oorschot, 1996,“Handbook of Applied
Cryptography”,Boca Raton, FL: CRC Press.
[10]B.V.Rama Devi et.al., “ A New
Steganographic Algorithm for Image Hiding
using GÖdelization under frequency
domain”,2011, IJARCS, Vol 2,No.2, pp 519-
522.
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