Introduction to Steganography

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Introduction to Steganography

• BSIT-7th
• Instructor Inam Ul Haq
• Inam.bth_at_gmail.com

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Table of content

• Information Hiding
• Steganography
• History
• Fields applied to Information Hiding
• Basic Terminologies
• Steganalysis
• Some Applications
• Some Tools
• Steganography Techniques

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Information Hiding
F. A. P. Petitcolas, R. J. Anderson, M. G. Kuhn,
Information Hiding A Survey, Proceedings of
the IEEE, special issue on protection of
multimedia content, 87(7)1062-1078, July 1999
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Information Hiding

• Information Hiding is a branch of computer
  science that deals with concealing the existence
  of a message
• It is related to cryptography whose intent is to
  render messages unreadable except by the intended
  recipients
• It employs technologies from numerous science
  disciplines
• Digital Signal Processing (Images, Audio, Video)
• Cryptography
• Information Theory\Coding Theory
• Data Compression
• Human Visual/Auditory perception
• There are four primary sub-disciplines of
  Information Hiding
• Steganography
• Watermarking
• Covert Channels
• Anonymity

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Steganography

• Steganography means covered writing
• A Greek word steganos means covered, protected or
  concealed
• Definition It is concealing any file, image,
  audio or video within another file.
• Most frequently, steganography is applied to
  images, but many other data or file types are
  possible
• Audio
• Video
• Text
• Executable programs
• Links

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History

• The concept of message hiding is not new its
  been around for centuries
• A Greek shaved the head of a slave, wrote a
  message, then waited for the hair to grow back
  before sending the slave to his destination
• Steganography (in the form of invisible ink) was
  used by Washington in the Revolutionary War
• Prior to the Civil War, quilts were sewn with
  special patterns to tell escaping slaves which
  direction to go and what to do
• In the 1980s, some of Margaret Thatchers
  cabinet documents were leaked to the press. She
  ordered that the word processors being used by
  government employees, encode their identity in
  the word spacing of the documents

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Fields Applied to Information Hiding

• Information Theory/Coding Theory
• Digital Signal Processing
• Discrete Fourier Transform/Discrete Cosine
  Transform
• Image/Audio/Video Processing
• Data Compression
• Cryptographic Principles
• Discrete Math
• Cryptographic Hashing
• Data Networks
• The Human Visual System/Human Auditory System
• Capabilities and limitations

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Basic Terminology

• The data to be hidden
• Plaintext / Secret message / Stego-message /
  Embedded data
• The data which will have a stego-message embedded
  in it
• Covertext / Cover-Object /
• Cover-Image\Cover-Audio\Cover-Video
• Target file
• The key used to make the stego-message secure
• Stego-Key / Secret Key / Key
• The file with the steganography-message embedded
• Stegotext / Stego-Object /
• Stego-Image\Stego-Audio\Stego-Video

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Watermarking

• Watermarking is very similar to steganography in
  that one of its goals is to not be detected
• Its primary goal is to not be able to be
  extracted or destroyed (at least not without
  destroying the cover too)
• Typically, watermarking is designed to protect
  intellectual property rights for images, sounds,
  and video
• If its easily removed or destroyed, those rights
  cannot be protected
• There is a popular program called StirMark which
  does just that
• Make it tamper proof

Anonymity
Anonymity is about concealing the sender and
receiver of messages and this is the least
studied sub-discipline of information hiding
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Steganalysis

• Steganalysis is the detection of data that has
  been hidden
• It is a cat and mouse game as one group of
  researchers come up with better ways to hide
  stuff, another group figures out how to detect it
  or perhaps just destroy it

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Applications of Information Hiding

• Covert military communications
• Covert police communications
• Criminals have learned that police are nearby
  when they hear encrypted communications, so they
  reduce their activity for the moment
• A steganographic system would prevent this
  detection
• Digital Rights Management protecting
  intellectual property such as images, music,
  electronic books, etc.
• Embedding textual data in medical images would
  better ensure that the picture belongs to a
  particular patient
• This technique could apply to personal pictures,
  sounds, and movies
• Tamper proofing ensuring a data file has not
  been changed

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Steganography tools

• Anubis
• BMP Secrets
• DarkCryptTC
• OpenPuff
• OpenStego
• StegFS
• StegoShare
• Other tools https//en.wikipedia.org/wiki/Stegano
  graphy_tools
• 12 best steganography tools http//www.topbestalt
  ernatives.com/best-steganography-software/

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Steganography tools (contt.)
StegoShare allows embedding of large files into
multiple images
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Steganography tools (contt.)
Free tool that implements three layers of hidden
data
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Steganographic Techniques - Substitution

• The most common method is to replace the Least
  Significant Bit (LSB) in substitution
• RSA Algorithm
• Hash LSB
• DEF CON 16
• See other techniques https//pdfs.semanticscholar
  .org/8946/d2ea49e2ca7c53c157bfe09c2b656fc841ce.pdf
  

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Exercise
1- What is covert Channel? 2- Write a detail note
on Anonymity. 3- Watermarking 4-
Fingerprinting 5- Explore StirMark 6- What are
different steganographic techniques? 7- Can you
embed secret message into image?