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STEGNOGRAPHY

AN ART OF HIDING INFORMATION

STEGANOGRAPHY

-- - AN ART OF HIDING DIGITAL INFORMATION

REASONS FOR SELECTING TOPIC

It was indeed difficult to select one topic from the long list hat was provided to us. We both believe that it is technology that binds this entire society together. The growing use of technology makes it extremely important for all of us to secure or hide our confidential information to the greatest extent possible. It is only with this guarantee of personal security that technology will be able to grow by leaps and bounds.

It was with this basic idea that we chose the topic of steganography-so that we would get the chance to learn and explore more about the lesser known world of steganography

INTRODUCTION

STEGANOGRAPHY :

STEGANOGRAPHY COMES FROM THE GREEK

WORD, IT MEANS COVERED OR SECRET

WRITING.

STEGAN-O-GRAPHY

COVERED WRITING

“The goal of steganography is to hide messages in such a

way that no one apart from the intended recipient even knows

that a message has been sent.”

This can be achieve by concealing the existence of

information within seemingly harmless carriers or cover

It can be understand by the following figure.

It supplements cryptography

And provides additional security to the information being transmitted.

Difference between cryptography and steganogaphy..

• At times these two technologies seem to converge while the objectives of the two differ. The two systems also use different methods altogether

• Cryptographic techniques "scramble" messages so if intercepted, the messages cannot be understood.

• Steganography, in an essence, "camouflages" a message and makes it invisible thus reducing the chance of a message being detected.

• This technology has in fact been used throughout recorded history.

History of Steganography

Steganography ancient origins can be traced back to 440 BC, from the Histories of Herodotus

Demeratus sent a warning about a forthcoming attack to Greece by writing it on a wooden panel and covering it in wax.

Histiaeus, who shaved the head of his most trusted slave and tattooed a message on it. After his hair had grown the message was hidden. The purpose was to instigate a revolt against the Persians.

STEGANOGRAPHY UNDER VaRIOUS MEDIA

Steganography in “TEXT”

Steganography in “IMAGES”

Steganography in “AUDIO”

STEGANOGRAPHY IN TEXT

I T I N VO LV E S T H R E E T Y P E S O F C O D I N G :

L I N E - S H I F T C O D I N G : H E R E , T E X T L I N E S A R E

V E RT I C A L LY S H I F T E D T O E N C O D E T H E D O C U M E N T

U N I Q U E LY.

W O R D - S H I F T C O D I N G : T H E C O D E W O R D S A R E

C O D E D I N T O D O C U M E N T B Y S H I F T I N G T H E

H O R I Z O N TA L L O C AT I O N S O F W O R D S W I T H I N T E X T

L I N E S , W H I L E M A I N TA I N I N G A N AT U R A L S P A C I N G

A P P E A R A N C E .

F E AT U R E C O D I N G : I N F E AT U R E C O D I N G ,

C E RTA I N T E X T F E AT U R E S A R E A LT E R E D , O R N O T

A LT E R E D , D E P E N D I N G O N T H E C O D E W O R D .

STEGANOGRAPHY IN IMAGES

Image Compression: Image compression offers a solution to large image files. Two

kinds of image compression are lossless and lossy compression.

Both methods save storage space but have differing effects on

any uncompressed hidden data in the image.

“Lossy” JPEG(Joint Photographic Experts Group) format files,

offers high compression, but may not maintain the original

image's integrity. Hence it is called “lossy”.

“Lossless” compression maintains the original image data

exactly, It is thus more favoured by stenographic techniques. E.g.:

(BMP ),(GIF) Formats.

IMAGE-BASED TECHNIQUES

O Least Significant

Bit Insertion

O Masking and

Filtering

LSB INSERTION

Replaces least significant bits with the message to be encoded

Most popular technique when dealing with images

Simple, but susceptible to lossy compression and image manipulation

LSB - Example

A sample raster data for 3 pixels (9 bytes)

may be:Inserting the binaryvalue for

A (10000001)changes

4 bits00100111 11101000 1100100000100110 11001000 1110100011001001 00100111 11101011

00100111 11101001 1100100000100111 11001000 1110100111001000 00100111 11101011

Best to use a gray scale palette or one with gradual changes in shades

Otherwise, it is best to use images with “noisy areas” – areas with ample color variation and without large areas of solid color

LSB Continued…

GRAYSCALE PALETTE

NEBULA PALETTE

“NOISY AREAS” - Example

Renoir painting

LSB - Uses

• Storing passwords and/or other confidential information

• Covert communication of sensitive data

• Speculated uses in terrorist activities• Being widely used to hide and/or transfer

illegal content

Masks secret data over the original data by changing the luminance of particular areas

During masking, it embed the message within significant bits of the cover image

Not susceptible to lossy techniques because image manipulation does not affect the secret message

MASKING & FILTERING

MASKING & FILTERING - Uses Digital Watermarking – provides

identification pertaining to the owner; i.e. license or copyright information

- Invisible vs Visible

Fingerprinting – provides identification of the user; used to identify and track illegal use of content

Visible Watermark - Example

STEGANOGRAPHY IN AUDIO

Methods of Audio Data Hiding

Low-bit encoding :

Phase coding :

Echo data hiding :

LSB CODING: Least significant bit (LSB) coding is the simplest way to embed information in a digital audio file. By substituting the least significant bit of each sampling point with a binary message, LSB coding allows for a large amount of data to be encoded. 

PHASE CODING:Phase coding relies on the fact that the phase components of sound are not as perceptible to the human ear as noise is. Rather than introducing perturbations, the technique encodes the message bits as phase shifts in the phase spectrum of a digital signal, achieving an inaudible encoding .

EChO-HIDING: In echo hiding, information is embedded in a sound file by introducing an echo into the discrete signal. Like the spread spectrum method, it too provides advantages in that it allows for a high data transmission rate and provides superior robustness when compared to the noise inducing methods. 

STEGANALYSIS

Steganalysis is the art and science of

detecting a secret communication.

Hiding a message will most likely leave

detectable traces in the cover medium.

The information hiding process changes the

statistical properties of the cover, which is a

steganalyst attempts to detect.

The process of attempting to detect statistical

traces is called statistical steganalysis.

ADVANTAGES AND DISADVANTAGES

ADVANTAGES :

Difficult to detect and Only receiver can detect.

It can be done faster with large no. of software's.

Provides better security for sharing data in LAN,MAN & WAN.

DISADVANTAGES:

The confidentiality of information is maintained by the algorithms, and

if the algorithms are known then this technique is of no use.

Password leakage may occur and it leads to the unauthorized access of

data.

If this technique is gone in the wrong hands like hackers can be very much

dangerous for all.

Steganography Sample Website

Here is the link for Sample Stenographic tool Website:

http://mozaiq.org/

My Questions

1. Salutations, Mr. Robertson of CIS 5371. The Florida Society of Math and Cryptography is proud to present you with an small exam for qualification into our society. The key for passing is studying. Cryptography is rigorous and only those with patience in themselves pass. We have an exam PO Box in Tallahassee. But please submit by 12/12.

Salutations, Mr. Robertson of CIS 5371. The Florida Society of Math and Cryptography is proud to present you with an small exam for qualification into our society. The key for passing is studying. Cryptography is rigorous and only those with patience in themselves pass. We have an exam PO Box in Tallahassee. But please submit by 12/12.

ANSWER

The Cryptography exam key is in PO Box 1212.

Bibliography:

WWW.GOOGLE.COM

WWW.WIKIPEDIA.COM

WWW.WEBOPEDIA.COM------IMAGES

WWW.THUNDERSTONE.COM

WWW.CITI.UMICH.EDU

WWW.GARYKESSLER.NET/LIBRARY/STEGANOGRAPHY.HTML

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