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STEGANOGRAPHY - PowerPoint

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STEGANOGRAPHY - PowerPoint Powered By Docstoc
					     A MESSAGE FROM LADEN
To:- Ashraf Hamid
Sub:- My picture
AFTER FEW DAYS
STEGANOGRAPHY
   Something lies beneath…
               Presented by:
         SATYAPRAKASH BEHERA
              Roll No: 11896
               8th Semester
             Computer Science
Today..
   What is steganography?
   Traces in history
   Modern day applications
   Why not cryptogrphy
   Steganographic model
   Steganography Examples
   Steganography Tools
   Conclusion
          What Is Steganography
   Steganography
       from the Greek word steganos meaning
        “covered”
       and the Greek word graphie meaning “writing”
   Steganography is the process of hiding of a
    secret message within an ordinary message and
    extracting it at its destination
   Anyone else viewing the message will fail to
    know it contains hidden/encrypted data
Historical Uses

  As early as the Greeks
    Tattooed body parts.
    Wax palettes
    Invisible Inks
   1st and 2nd World Wars
   German spies used invisible ink to print very small dots on letters.
   Microdots – Blocks of text or images scaled down to the size of a regular
     dot.
Modern day applications

  Avoid third party snooping
  Security reinforcement layer to
   cryptography
  Hiding copyright info: digital watermarks
   and fingerprinting (growing due to web
   piracy)
  Data encapsulation : data and still
   images
Why not Encryption?
                              Confidentiality




       Steganography                                 Encryption
  (hide existence of the secret                 (encrypt the message,
              message,
                                                    but do not hide the
     but do not use encryption)                           message)



 •     Ideally nobody can see both              •    Anybody can see both
       parties are secretly                          parties are communicating
       communicating.                                in secret.


 •     Innocent.                                •    Suspicious.
Motivation - Steganography
 Hides existence of files
 Examples:
     User   is tortured to give password to encrypted
      data
     Court order demands access to encrypted
      files
   Bottom line: No one can prove the files
    even exist!
HOW IT WORKS
HOW IT WORKS

                        Terminology
    Payload
        The data to be hidden
    Package/stego-text
        “enciphered” information
    Carrier/Cover Image
        The original file
    Encoding Density
        Percentage of payload to carrier
        The lower the density, the “more hidden” the file is
        Steganographic model
   Participants of Information hiding Workshop
    presented:
                              Stego Key (K)                Stego Key (K)


       cover C


                   Stego                       Stego
                   Function                    Inverse
                   fE                Stego S   Function fE-         Embedded (E)
                                               1
    Embedded (E)

                    Sender                         Recipient



                                STEGOSYSTEM
HOW IT WORKS


  Basic Principle in Steganography

                Secret
                Image
                                                     Stego
                                                     Object
       Cover
       Image
                         Encoder



                                          Key
       Secret            Decoder
       Image                                    Communication
                                                  s Channel

                                   Original
                                    Cover
HOW IT WORKS

     Steganography – Carrier Files
 Steganography Carrier Files
  TEXT

  IMAGE

      bmp,jpeg,gif
  AUDIO

      wav,mp3
  VIDEO
HOW IT WORKS

           Steganography Techniques


      Text
          Document
          XML
      Images
          LSB, Masking and
           Filtering
      Audio
          LBC,PhaseCoding
HOW IT WORKS

      Information Hiding in Documents
  •   One of three techniques are applied to hiding data:
       – Line Shift Coding - Vertical shifting of lines




                                 Shifts lines up slightly up or down               h-i
             Shifted up
                                                                                    h+i
              slightly         Lines to be shifted decided by Codebook
       –   Word Shift Coding - Horizontal spacing between each word

            Shift of words slightly left or right, decided by codebook
            An Example of this
                                          “Example” is shifted to the left. “this” is
            AnExample of this                         shifted to the right

       –   Feature Coding - Analyse document, then pick features to change e.g. text
           height
HOW IT WORKS

                         Text Techniques
                                              Dear Friend , Especially for you - this red-hot
                                              intelligence. We will comply with all removal
                                              requests . This mail is being sent in compliance
                                              with Senate bill 2116 , Title 9 ; Section 303 !
                                              THIS IS NOT A GET RICH SCHEME.Why work
                                              for somebody else when you can become rich
                                              inside 57 weeks . Have you ever noticed most
                                              everyone has a cellphone & people love
      Text being hidden: “I'm having         convenience . Well, now is your chance to
                                              capitalize on this . WE will help YOU SELL
       a great time learning about computer   MORE and sell more ! You are guaranteed to
       security”.                             succeed because we take all the risk ! But don't
                                              believe us . Ms Simpson of Washington tried us
                                              and says "My only problem now is where to park
                                              all my cars" . This offer is 100% legal . You will
                                              blame yourself forever if you don't order now !
                                              Sign up a friend and you'll get a discount of 50% .
                                              Thank-you for your serious consideration of our
                                              offer . Dear Decision maker ; Thank-you for your
                                              interest in our briefing . If you are not interested in
                                              our publications and wish to . . .
HOW IT WORKS


             Text Techniques(XML)

       Using tag structure of XML
        to hide information

                                          Stego data:
                                              <img
             Stego key:
                                       src=”foo1.jpg”></img
          <img></img> … 0                        >
             <img/> … 1              <img src=”foo2.jpg”/>
                                     <img src=”foo3.jpg”/>
                                     <img src=”foo4.jpg”/>
            Bit String: 01110                 <img
                                       src=”foo5.jpg”></img
                                                 >
HOW IT WORKS


      Information Hiding In Images
     In a standard 24bit bitmap you
      have 3 color components per pixel:
      Red, Green, and Blue
     Each component has 2^8 (256)
      values
          Notice that 11111111 and
           11111110 won’t leak any
           distinguishing differences in most
           images
     In a 3 mega pixel photo, you can
      hide 9 megabits of information
      with the above technique
          That’s the equivalent of a 225 page
           book!!
                   Steganography in Images
                            (LSB)
    Assume the original three pixels are represented by
     the three 24-bit words below:
    (00100111 11101001 11001000) (00100111 11001000 11101001) (11001000 00100111 11101001 )

    The binary value for the letter A is (10000011). Inserting the
     binary value of A into the three pixels, starting from the left
     byte, would result in:
    (00100111 11101000 11001000) (00100110 11001000 11101000) (11001001 00100111 1101001)
            More Examples
                      How?
                      •Drop all but the last 2 bits
                      of each color component
                      in each pixel
                      •Enhance brightness 85x

111100 00



                  11110000

                   2 MSB
          Steganography in Images
           (Masking and Filtering)

   Masking and Filtering
     manipulates the
      luminance of
      particular areas of
      the image in order
      to encode data
    Masking and filtering (contd.)
 Cover pixel : 01011100
 Secret image pixel: 11101010

 Resultant pixel: 01011101 (3+5)

 The contribution of each pixel can be
  varied to achieve desired effect.
                                                 TOP SECRET
                   +
                                                  =


8-bit (256 grayscale)
images.



Example: Copyright Fabian A.P. Petitcolas,
Computer Laboratory, University of Cambridge
http://www.cl.cam.ac.uk/~fapp2/steganography/image_downgrading/
Sacrificing 2 bits of cover to carry 2 bits of
               secret image




     Original Image    Extracted Image
Sacrificing 5 bits of cover to carry 5 bits of
               secret image




        Original Image     Extracted Image
HOW IT WORKS

                       Audio
   Audio signals are encoded using sampling rates
    (frames) and a frequency range
     The human ear can only distinguish from 20Hz to
      20KHz
     However, when there are two sounds simultaneously
      with one louder than the other, only the louder is
      generally heard
         Steganography in Audio
   Low Bit Coding
     Most digital audio is created by sampling the
      signal and quantizing the sample with a 16-bit
      quantizer.
     The rightmost bit, or low order bit, of each
      sample can be changed from 0 to 1 or 1 to 0
     This modification from one sample value to
      another is not perceptible by most people and
      the audio signal still sounds the same
          Steganography in Audio
   Phase Coding
     Relies on the relative insensitivity of the
      human auditory system to phase changes
     Substitutes the initial phase of an audio signal
      with a reference phase that represents the data
     More complex than low bit encoding, but it is
      much more robust and less likely to distort
      the signal that is carrying the hidden data.
HOW IT WORKS


                          Video
    The human eye can only perceive approx 24
     frames per second
      Increase the frame rate and hide the payload in the
       superfluous frames.
      Since this may be visually detected just encode each
       frame like the examples
Steganography - Tools

Steganography Tools
 Steganos
 S-Tools (GIF, JPEG)
 StegHide (WAV, BMP)
 Invisible Secrets (JPEG)
 JPHide
 Camouflage
 Hiderman
 Many others…
Conclusions

Expect to see, or not see, Steganography
 in countries where cryptography is
 outlawed
One area of Information Assurance still in
 its infancy
References
 NetIP Security Resource
     http://www.netip.com/links/stegonography.htm
 StegoArchive
     http://www.stegoarchive.com/
 Computer Forensics, Cybercrime and Steganography Resources
     http://www.forensics.nl/steganography
 A Detailed Look at Stegonagraphic Techniques and their Use in an Open-
 System Environment
     http://www.sans.org/rr/whitepapers/covert/677.php
 Wikipedia
     http://en.wikipedia.org/wiki/Steganography
 The Code Project
     http://www.codeproject.com/cpp/HideIt.asp
 Steganalysis: The Investigation of Hidden Information
     http://www.simovits.com/archive/it98jjgmu.pdf
 Spam Mimic
     http://www.spammimic.com/
 Steganalysis: Detecting Hidden Information with Computer Forensic
 Analysis
     http://www.giac.org/practical/GSEC/Pierre_Richer_GSEC.pdf
THANK YOU

				
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posted:8/19/2011
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