This document discusses the history and techniques of steganography. It begins by defining steganography as concealed writing and provides some historical examples of its use. It then describes how information can be hidden in various carriers like images, audio, and video. The document outlines several steganography techniques including LSB substitution and modifying DCT coefficients in images. It also discusses embedding data in IP datagrams and detecting steganography. In closing, it notes both benefits and risks of using steganography.

1. PREPARED BY:
RESHMI SASIDHARAN

2.  Steganography is a word that is derived from
Greek.
 Stegano- covered and Graphie- writing
 Hidden writing that has no existence.

3.  Histaiaeus to Aristagorus about war via his messenger
 Milk of thithymallus revealed on heating on a paper
 Ounce of alum and pint of vinegar used to write on
boiled hard egg shell stays on albumen
 Write on a bark of wood and cover it with wax
 Ancient chinese usage of silk

4. In Information hiding, the carriers can be
 Plain text
 Image
 Video clip
 Audio
 IP datagram

5.  Can be done using cryptography, steganography or
watermarking.
 Cryptography and steganography have a slight
difference in physical appearance.
 Steganography and watermarking use the same
techniques and the data tranfered doesn’t appear to
have been embedded with some secret code, as
contrast to cryptography.
 But in steganography, intruder doesn’t detect a
message and in DWM, intruder cant remove or
replace the message to render it meaningless.

6. Big rumble in New Guinea. The war on
celebrity acts should end soon.Over four
big ecstatic elephants replicated.
Bring two cases of beer
Apparently neutral's protest is thoroughly discounted and
ignored. Isman hard hit. Blockade issue effects pretext for
embargo on byproducts, ejecting suets and vegetable oils.
Perishing sails from ny june 1

7.  Use of selected characters
 Look up table coordinating to extra spaces
 secret integer key that integers are positions of
letters in subsequent words of cover text. Key
is ‘1, 1, 2, 3, 4, 2, 4’
“A team of five men joined today”
Secret message is atfvoa
• For the above case, ‘0’ to indicate a blank
space.

8.  LSB technique
Why?
RGB patterns in a bitmap
 Bit flipping at LSB is undetectable
00100111 11101001 11001000 00100111 11001000
11101001 11001000 00100111
 lets send an equivalent of A- 01100101
 Then
00100110 11101001 11001001 00100110
11001000 11101001 11001000 00100111

9.  Text lines shifted up/down (40 lines text  240 codes)
 word space coding
 character encoding - minor changes to shapes of characters
 works only on “images” of text e.g., PDF, postscript

10. 1.Image is broken into data units each of them
consists of 8 x 8 block of pixels.
2.DCT is applied to each pixel of each data unit.
3. One DCT Coefficient is generated for each pixel
in data unit.
4.Quantize
5. The LSB of binary equivalent the quantized DCT
coefficient can be replaced by a bit from secret
message.
6. Encoded to produce compressed Stego Image.

12. LSB coding
•Embed the data into the lsb at the 16
bit length data
Phase coding
•As phase shifts in the phase spectrum
Echo hiding
•Has three attributes-amplitude, decay
rate and offset.

13.  The original cover video consists of frames represented
by Ck(m,n) where 1 <k <N, ‘N’ is the total number of
frames
 m,n are the row and column indices of the pixels,
respectively.
 The binary secret message denoted by Mk(m, n)
 Mk(m, n) is defined over the same domain as the host
Ck(m,n).
 The stego-video signal is represented by the equation
Sk(m, n) = Ck(m, n)+a(m, n) Mk(m, n) ,
k = 1, 2, 3 . . .N

14. IP DATAGRAM

15. Datagram 3-bit Flag
field
13-bit
fragment offset
Remarks
1 010 00…00 Datagram 1
covertly
communicating
‘1’
2 000 00…00 Datagram 2
covertly
communicating
‘0’
FLAG FIELD

16. Is a process to detect steganography
Firstly, stego media is to be detected
Determine if the detected media has the
hidden message
If yes, then recover the message

17.  Known carrier attack: The original cover
media and stego media both are available for
analysis.
 Steganography only attack: In this type of
attacks, only stego media is available for
analysis.
 Known message attack: The hidden message
is known in this case.
 Known steganography attack: The cover
media, stego media as well as the
steganography tool or algorithm, are known.

18.  Changes in electronic media can degrade the
image.
 Visual detection steganalysis technique:
 compare stego image with original cover image by
applying dct.
 cropping or padding the stego image to fit the size
 increase or decrease of unique colours in stego
images.

19.  It doesn’t attract attention
 Packet sniffing barrier
 Makes internet surveillance difficult
 Difficult to prove it exists

20.  Threat to national security when used by wrong
hands
 Problem is when the sender and receiver have a
misunderstanding and data is misused by intruder
 If stego media is modified
 Bit flipping by noise when in transmission

21.  Modern day printers
 Use by terrorists
 Military applications
 Government organizations can use it to
communicate.

22. Integer key is
1111138X303
Thank you