2.
Introduction
History
Basic Model Of Steganography
Steganography Technique
Why
steganography works
Requirements that must be satisfied
Applications of
Attacks
Steganography
to Steganography
References
3.
Steganography is of Greek origin where Greek words
steganos meaning "covered or protected"
graphei meaning "writing "
Hence steganography means concealed writing [3].
Steganography is the art and science of embedding secret messages in cover
message in such a way that no one, apart from the sender and intended
recipient, suspects the existence of the message.
4.
5. Tattooing message on
slaves head
Writing messages on wood underlying
wax tablets
PERSHING SAILS FROM NY JUNE 1
Use of invisible inks
Use of null ciphers
8. Inputs of Embedding Algorithm
Secret
Message
Cover Image
1
Cover Image
2
Secret Key
Steganographic Algorithm
Data
Hiding
Stego Object
Data Extraction
Secret Key
Inputs of Extraction Algorithm
Secret
Message
9. In this method instead of hiding data in LSB of RGB components, data is hidden
as shown in following example:
Let the data to be hidden is word 'ABC'.
Find the ASCII code of every character to be hidden.
ASCII code of A is 65 and its corresponding binary is 01000001
ASCII code of B is 66 and its corresponding binary is 01000010
ASCII code of C is 67 and its corresponding binary is 01000011
10. EMBEDDING METHOD
Let the RGB component of first pixel:
RED
1
0
1
1
0
GREEN
0
0
1
0
1
0
0
1
BLUE
1
0
1
0
1
0
0
1
1
0
1
1
0
1
Red component is replaced by ASCII code of A in binary i.e. 01000001 :
RED
0
1
0
0
0
GREEN
0
0
1
0
1
0
0
1
BLUE
1
0
1
0
1
0
Similarly,
Green component of second pixel is replaced by ASCII code of B
and
Blue Component of third pixel is replaced by ASCII code of C
1
1
11. Inputs: - Text file, cover image 1, cover image 2 and secret key.
Output: - Stego image.
Begin
1. Select text file,
convert into binary and calculate number of bits
2. Select cover image 1 for hiding purpose
find the number of pixels,
split it into RGB components
3. If bits are compatible with the image resolution, then
start sub iteration 1, else
start sub iteration 2
4. Provide security key
5. Select cover image 2 to hide distorted stego image
END
12. SUB ITERATION 1
Replace red component of the first pixel with first character
Replace green component of the second pixel with second character.
Replace blue component of the third pixel with third character
And repeat iterations until pixels get exhaust
Stop sub iteration 1
SUB ITERATION 2
Replace necessary bits as in immediate component of each pixel
Store the information about bits embedded in a binary address file
And repeat iterations until pixels get exhaust
Stop sub iteration2
13. Text File
Convert into
binary & cal.
no. of bits
If no. of bits=Resolution
Find number
of pixels in
image
If no. of bits ≠ Resolution
Replace red comp.
of 1st pixel with 1st
character
Repeat until
pixels exhaust
Replace
necessary bits in
pixels
Replace green
comp. of 2nd pixel
with 2nd character
Store info. about
bits embedded in
binary address
file
Replace blue
comp. of 3rd pixel
with 3rd character
Secret Key
Provide
secret key
Cover Image 1
Cover
Image 2
Hide
distorted
image
Repeat until
pixels exhaust
Stego
Object
14. Input: - Stego image and secret key.
Output: - Secret text file.
Begin
1. Browse the stego image.
2. Choose the folder in which you want to extract the hidden text file.
3. Provide necessary security key.
4. Convert the binary file into human readable form.
End
15. Human Visual System (HVS) –
Insensitivity to gradual changes in shade
Insensitive to high frequencies and blue region of visible spectrum
Human Audio System (HAS) –
Sensitive to additive random noise
Inability to perceive absolute phase
16. The following is a list of main requirements that steganography techniques
must satisfy [4]:
a)
The integrity of the hidden information after it has been embedded inside
the stego object must be correct.
b)
The stego object must remain unchanged or almost unchanged to the
naked eye.
c)
In watermarking, changes in the stego object must have no effect on the
watermark.
d)
Finally, we always assume that the attacker knows that there is hidden
information inside the stego object.
17.
Used by intelligence agencies.
Used by military forces to send secret messages.
Used in modern printers.
Used in digital watermarking.
Used by terrorists.
Used for corporate espionage to send out trade secrets.
18. Additive Noise,
Filtering
Cropping
Compression
Rotation and Scaling
Statistical Averaging
Multiple Watermarking
Depending on these types of attacks steganography may
be classified as robust or fragile [2][4].
19. [1] Vipul Sharma, Sunny Kumar, “ A New Approach to Hide Text in Images
Using Steganography”, IJARCSSE, Volume 3, Issue 4, ISSN: 2277
128X, April 2013.
[2] James C. Judge, “Steganography: Past, Present, Future”, SANS Institute
2001.
[3] Ross J. Anderson, Fabien A.P. Petitcolas, “On The Limits of
Steganography”,
IEEE
Journal
of
Selected
Areas
in
Communications, 16(4):474-481, ISSN 0733-8716, May 1998.
[4] Ananthi S, Anjanadevi A “Reversible Image Data Hiding Using Predictive
Coding Technique Based on Steganograpic Scheme”, IOSR Journal of
Engineering (IOSRJEN) ISSN: 2250-3021 Volume 2, Issue 7(July 2012).
20. [5] Shashikala Channalli, Ajay Jadhav, “Steganography An Art of Hiding
Data”, International Journal on Computer Science and Engineering Vol.1(3),
2009.
[6] Emad T. Khalaf, Norrozila Sulaiman,"A Robust Data Hiding Technique
based on LSB Matching", World Academy of Science, Engineering and
Technology 58, 2011.
[7] Atallah M. Al-Shatnawi, "A New Method in Image Steganography with
Improved Image Quality",Applied Mathematical Sciences, Vol. 6, 2012.
