2. INTRODUCTION
In Greek terminology,
STEGANOS – “Covered”
GRAPHIE – “Writing”
Steganography is the art and science of writing hidden messages in
such a way that no one apart from the intended recipient knows of
the existence of the message.
This can be achieved by concealing the existence of information
within seemingly harmless carriers or cover.
Carrier: text, image, video, audio, etc
3. History of Steganography
440 B.C.
Histiaeus shaved the head of his most trusted slave and tattooed it
with a message which disappeared after the hair had regrown. To
instigate a revolt against Persians.
1st and 2nd World Wars
German spies used invisible ink to print very small dots on letters.
A message sent by a German spy during World War II read:
“Apparently neutral’s protest is thoroughly discounted and ignored.
Isman hard hit. Blockade issue affects for pretext embargo on by-
products, ejecting suets and vegetable oils.”
By taking the second letter of every word the hidden message
“Pershing sails for NY June 1” can be retrieved
4. Evolution
Cryptography
Steganography
Watermarkin
g
5. Steganography Terms
Carrier or Cover File - A Original message or a file in which
hidden information will be stored inside of it .
Stego-Medium - The medium in which the information is hidden.
Embedded or Payload - The information which is to be hidden or
concealed.
Steganalysis - The process of detecting hidden information inside a
file.
7. Steganography in text
Line Shift Coding: Lines are vertically shifted. In line shift coding, shift
various lines inside the document up or down by a small fraction (such as
1/300th of an inch).
Word Shift Coding: Code words are horizontally shifted. The decoding
technique is measuring the spaces between each word and a left shift
could represent a 0 bit and a right shift representing a 1 bit.
The quick brown fox jumps over the lazy dog.
The quick brown fox jumps over the lazy dog.
White Space Manipulation: It is done by adding a certain amount of
white space to the end of lines. The amount of white space corresponds
to a certain bit value.
8. Steganography in images
The simplest and most common type of steganography is
LSB (least significant bit). The one’s bit of a byte is used
to encode the hidden information.
Suppose we want to encode the letter A (ASCII 65 or
binary 01000001) in the following 8 bytes of a carrier
file.
01011101 11010000 00011100 10101100
11100111 10000111 01101011 11100011
becomes
01011100 11010001 00011100 10101100
11100110 10000110 01101010 11100011
9. Variations of LSB
Use password as a seed for pseudo random number
generator.
Use only those bytes separated by the value of the next
random number to hide data.
Advantages - More difficult to detect and decode.
Disadvantage – Limits the number of bytes that are
available for holding the payload.
10. Least significant bit insertion technique
4 bits to hide the secret image
Host Pixel: 10110001
Secret Pixel: 00111111
New Image Pixel: 10110011
11. Steganography in audio
PHASE CODING
SPREAD SPECTRUM
Makes use of the fact that small changes are more difficult for the
human eye or ear to detect at high energy levels (loud audio or
bright video).
The message is hidden in those areas of the carrier file with the
greatest energy.
12. Steganography in video
For video, a combination of sound and image techniques can be used.
This is due to the fact that video generally has separate inner files for the
video (consisting of many images) and the sound.
So techniques can be applied in both areas to hide data. Due to the size of
video files, the scope for adding lots of data is much greater and therefore
the chances of hidden data being detected is quite low.
14. APPLICATIONS OF STEGANOGRAPHY
Secure Communication
• It is a state-of-the-art digital steganography
software package developed for confidential
multimedia communication.
•The software allows the user to select a
multimedia data file or "container" for
embedding hidden text, audio sequence, video
clip, or any form of data file.
•The contents of the text message are hashed
with those of the container file to produce a key
file. The key file is also known as
a “Stegfile”.
15. DIGITAL WATERMARKING
Digital watermarking software for copyright protection of
digital images, music CDs,DVDs, and other forms of
multimedia data.
How robust a watermark is depends on whether it can survive
various "attacks" that include contrast changes, cropping,
scratches, and filtering.
The digital image watermark is able to survive most of these
attacks.
.
16.
17. DIGITAL SIGNATURE AUTHENTICATION
•It is a software product specifically developed to prevent malicious tampering of
private and confidential documents.
•This will detect any unwarranted tampering and alert the receiver side
immediately. A digital signature and a multimedia container password are
embedded into the confidential document.
18. DIGITAL LINKAGE AND STORAGE
It provides a secure data linkage between a digital image and
attribute text information.
The attribute information can be any personal records
The main function is to securely link the personal record and
digital photograph together and then create a hash file that can
be safely stored in a database.
This hash file is unique and can only be decoded with the
original photograph and associated personal record.
An optional password is also available to protect the hash file
prior to data storage.
20. CONCLUSION
Steganography can protect data by hiding it but using it alone may
not guarantee total protection.
In case of encryption, by seeing the meaningless appearing
sequence of bits enemy can detect that some illegal message is
being sent.
However, if one uses both methods, this will lead to ‘security in
depth’.
The message should first be encoded using a strong encryption
algorithm and then embedded into a carrier.
21. REFERENCES
Steganography And Digital Watermarking Jonathan
Cummins, Patrick Diskin, Samuel Lau and Robert Parlett,
School of Computer Science, The University of Birmingham.
www.scribd.com/doc/27459895
www.authorstream.com/Presentation/pavankumar
4b7-473085-steganography/
