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My Seminar Topic for 6th semester of Engineering. This topic is related to data hiding.

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STEGANOGRAPHY

… the art of Hiding Information

Sibaka Mahapatra

Computer Science

3rd Year, Sec-E

0801288242


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Table ofContents

  • Introduction

  • Steganography

  • History

  • Classification

  • Working Principle

  • LSB Substitution

  • Injection

  • Flow Chart

  • Tools & Techniques

  • Steganography Tools

  • Steganalysis Tools

  • Usage & Future Application

  • Modern Printers

  • Water Marking

  • Future Application

  • Conclusion


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STEGANOGRAPHY

  • Derived from the Greek words, Steganos (Covered) & Grapto (Writing)

  • Practice of hiding private or sensitive information within something

  • that is usually not suspected

  • Steganography in the modern day sense refers to information or a

  • file that has been concealed inside a digital Picture, Video or Audio file

  • Science of hiding information in such a way that no one suspects the

  • information exists

  • Steganography is usually combined with Cryptography

  • When information or a file is hidden inside a carrier file, the data is

  • encrypted with a password. Referred as ‘Steganalysis’


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HISTORY

  • Earlier invisible ink was used to write information on pieces of paper

  • Head of messengers were shaved so, a message could be written on it

  • Wax tablet was peeled on whichmessage was to be written & refilled

  • Null cipher sent by the German embassy in World War I

  • “PRESIDENT'S EMBARGO RULING SHOULD HAVE IMMEDIATE NOTICE. GRAVE SITUATION AFFECTING INTERNATIONAL LAW. STATEMENT FORESHADOWS RUIN OF MANY NEUTRALS. YELLOW JOURNALS UNIFYING NATIONAL EXCITEMENT IMMENSELY.”

  • (Taking the first letter in each word of message reveals the hidden text.)

  • “ PERSHING SAILS FROM NY JUNE 1”


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CLASSIFICATION

STEGANOGRAPHY

PHYSICAL

DIGITAL

NETWORK

PRINTED


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WORKING PRINCIPLE

STEGANOGRAPHY METHODS

Substitution

Injection


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SUBSTITUTION

  • Altering/Replacing The LSB

  • When files are created there are usually some bytes in the file that aren't

  • really needed, or are unimportant

  • These areas of the file can be replaced with the information that is to be

  • hidden, with out significantlyaltering the file ordamaging it

  • Thisallows a person to hide information in the file and make sure that no

  • human could detect the change in the file

  • The LSB method works best in Picture files that have a high resolution

  • and use many different colors, and with Audio files that have different

  • sounds and are of a high bit rate

  • It usually does not increase file size, but depending on size of the

  • information that is to be hidden, the file can become noticeably distorted


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INJECTION

  • Injection

  • Injection is a relatively simple method than altering the Least

  • Significant Bit (LSB) technique

  • Injection method involvesdirectly injecting the secret information into

  • the carrier file

  • The Payload and Carrier message are directly fed into the specially

  • designed Stegosystem encoder

  • The main problem with this method is that it can significantly increase

  • the size of the carrier file


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TERMINOLOGY

  • Carrier File -A file which has hidden information inside it

  • Steganalysis - Process of detecting hidden information inside a file

  • Stego-Medium - The medium in which the information is hidden

  • Payload - The information which is the be concealed

  • Redundant Bits - Pieces of information inside a file which can be

  • overwritten or altered without damaging the file


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FLOW CHART

Payload

Stegosystem encoder

Carrier

Channel

or

Medium

KEY

Stegosystem Decoder

Original

Message



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MATLAB CODE

Hare = imread('arctic_hare.bmp', 'bmp');F15 = imread('F15.bmp', 'bmp');n = 4; % Number of bits to replace 1 <= n <= 7[Stego, Extracted] = LSBHide(Hare, F15, n);figure, imshow(Stego)figure, imshow(Extracted)

where

function [Stego, Extracted] = LSBHide(Cover, Hidden, n)%LSBHide% [Stego, Extracted] = LSBHide(Cover, Hidden, n)% Hide Hidden in the n least significant bits of CoverStego = uint8(bitor(bitand(Cover, bitcmp(2^n - 1, 8)) , bitshift(Hidden, n - 8)));Extracted = uint8(bitand(255, bitshift(Stego, 8 - n)));


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OTHER TYPES…

  • Parity coding

    It breaks the sound signal into areas & then hides the message in the parity bit. If parity does not match, it adjusts LSB of one of the samples to get the required parity.

  • Spread spectrum

    It makes use of the fact that small changes are more difficult for the human eye or ear to detect at high energy levels. The message is hidden in those areas of the carrier file with the greatest energy.

  • BPCS

    It is the most efficient. Embedded data can be over 50% the size of the carrier without affecting quality noticeably.


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OTHER TYPES

  • Phase coding

    It makes use of the fact that the human ear is less sensitive to phase changes than amplitude changes. The following steps are applied:

  • Break the signal into no. of segments where the segment length equals the message length

  • Apply DFT to each segment & store phase, amplitudes in an array

  • Encode message into the phase vectors of the first segment only

  • Adjust all subsequent segments to preserve relative phase difference

  • Reconstruct the wave by inverse DFT


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STEGANOGRAPHY TOOLS…

  • MP3Stego

  • Hides information in MP3 files during the compression process. The

  • data is first compressed, encrypted and then hidden in the MP3 bit stream

  • JPHide and JPSeek

  • JPHIDE and JPSEEK are programs which allow you to hide a file in a jpeg

  • visual image. There are lots of versions of similar programs available on

  • the internet but JPHIDE and JPSEEK are rather special

  • BlindSide Cryptographic Tool

  • Secret messages are passed in a form such that one would not suspect the

  • message that is being transferred. The Blindside utility can hide files

  • of any variety, within a Windows Bitmap image (BMP file)


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STEGANOGRAPHY TOOLS

  • GIFShuffle

  • Used to conceal messages in GIF images by shuffling the colourmap,

  • which leaves the image visibly unchanged. gifshuffle works with all GIF images, including those with transparency and animation, and in addition provides compression and encryption of the concealed message

  • wbStego

  • A tool that hides any type of file in bitmap images, text files, HTML files or Adobe PDF

  • files. The file in which you hide the data is not optically changed

  • StegoVideo

  • Allows to hide any file in a video sequence. When the program was created,

  • different popular codec’s were analyzed and an algorithm was chosen which provides small data loss after video compression. MSU StegoVideo can be used as VirtualDub filter or as standalone .exe program, independent from VirtualDub


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STEGANALYSIS TOOLS

  • StegAlyzerAS

  • Capability to scan the entire file system, or individual directories, on suspect

  • media for the presence of Steganography application artifacts. Can perform

  • an automated or manual search of the Windows Registry to determine

  • whether or not any Registry keys or values exist that can be associated with

  • a particular Steganography application

  • StegAlyzerSS

  • Capability to scan every file on the suspect media for the presence of

  • hexadecimal byte patterns, or signatures, of particular Steganography

  • applications in the files.

  • Digital Invisible Ink Toolkit

  • Provides a simple Java-based Steganography tool that can hide a message

  • inside a 24-bit color image so that knowing how it was embedded, or

  • performing statistical analysis, makes it easy to find the concealed info.


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APPLICATION

Steganography is used by some modern printers, including HP and Xerox brand color laser printers. Tiny yellow dots are added to each page. The dots are barely visible and contain encoded printer serial numbers, as well as date and time stamps.

Steganography can be used for digital watermarking, where a message (being simply an identifier) is hidden in an image so that its source can be tracked or verified.



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CONCLUSION

In the Information age


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THANK YOU ALL

… for your Patient Hearing

Sibaka Mahapatra

Computer Science

3rd Year, Sec-E

0801288242


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