STEGANOGRAPHY

Sibaka MahapatraComputer Science

3rd Year, Sec-E0801288242

… the art of Hiding Information

Table of ContentsIntroduction 1. Steganography2. History3. Classification

Working Principle1. LSB Substitution2. Injection3. Flow Chart

Tools & Techniques1. Steganography Tools2. Steganalysis Tools

Usage & Future Application1. Modern Printers2. Water Marking3. Future Application

Conclusion

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’

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 which message 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”

CLASSIFICATION

STEGANOGRAPHY

PHYSICAL PRINTEDDIGITAL NETWORK

WORKING PRINCIPLE

STEGANOGRAPHY METHODS

Substitution Injection

SUBSTITUTIONAltering/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 significantly altering the file or damaging it

• This allows 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

INJECTION

Injection

• Injection is a relatively simple method than altering the Least Significant Bit (LSB) technique

• Injection method involves directly 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

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 to be concealed

• Redundant Bits - Pieces of information inside a file which can be overwritten or altered without damaging the file

FLOW CHART

Stegosystem encoder

Stegosystem Decoder

KEY

Carrier

Original Message

Channel or

Medium

Payload

ILLUSTRATION

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)

wherefunction [Stego, Extracted] = LSBHide(Cover, Hidden, n)

%LSBHide% [Stego, Extracted] = LSBHide(Cover, Hidden, n)

% Hide Hidden in the n least significant bits of Cover

Stego=uint8(bitor(bitand(Cover,bitcmp(2^n-1,8)),bitshift(Hidden,n-8)));Extracted = uint8(bitand(255, bitshift(Stego, 8 - n)));

• 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.

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

OTHER TYPES

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)

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

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.

APPLICATION

• Modern Printers Steganography is used by leading manufacturers in digital & laser printers, including HP and Xerox. Here, 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.

• Digital Watermarking Steganography is used for digital watermarking, where a message is hidden in an image so that its source can be tracked or verified.

• e-mail Spam e-mail messages is encrypted steganographically. Coupled with the "chaffing and winnowing" technique, a sender gets messages out and cover their tracks all at once.

FUTURE APPLICATION

• Alleged use by terrorists An example showing how terrorists may use forum avatars to send hidden messages. This avatar contains the message "Boss said, we should blow up the bridge at midnight." encrypted with http://mozaiq.org/encrypt using "växjö" as password.

• Alleged use by intelligence services In 2010, the FBI revealed that the Russian foreign intelligence service uses customized steganography software for embedding encrypted text messages inside image files for communicating with illegal agents stationed abroad.

CONCLUSION

• Steganography is the art of hiding sensitive data without generating unnecessary curiosity and suspision among foreign party

• Steganalysis is the technique to detect Steganography

• The research to device strong steganographic and steganalysis technique is a continuous process

• With proper usage Steganography can prove to be the ultimate solution to information hidding.On the contrary, its misuse is devastating and unthinkable.

THANK YOU ALL

Sibaka MahapatraComputer Science

3rd Year, Sec-E0801288242

… for your Patient Hearing