Steganography

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Steganography Steganalysis

• Multimedia Security Systems
• Spring 2006
• Hi Tae Shin

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Project Objective

• To study about the current technologies of
  steganography
• To implement steganalysis to detect
  steganographic messages in digital images
• To study about and implement the extended
  steganography

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Steganography (1)
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Steganography (2)

• Steganography vs. Cryptography
• Steganography vs. Digital Watermarking
• Images
• LSB
• DCT encoding LSB
• Spread Spectrum
• Audio
• LSB
• Phase Coding
• Spread Spectrum
• Tone Insertion
• Echo Data Hiding

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Steganalysis

• The goal of steganalysis is to identify suspected
  information streams, determine whether or not
  they have hidden messages encoded into them, and,
  if possible, recover the hidden information.
• Challenge of Steganalysis
• The suspect information stream, such as a signal
  or a file, may or may not have hidden data
  encoded into them.
• The hidden data, if any, may have been encrypted
  before inserted into the signal or file.
• Some of the suspect signal or file may have noise
  or irrelevant data encoded into them (which can
  make analysis very time consuming).
• Unless it is possible to fully recover, decrypt
  and inspect the hidden data, often one has only a
  suspect information stream and cannot be sure
  that it is being used for transporting secret
  information.

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Steganalysis Statistic (1)

• Statistical tests can reveal that an image has
  been modified by steganography by determining
  that an images statistical properties deviate
  from a norm.
• ?2 test determine whether an image shows
  distortion from embedding hidden data.

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Steganalysis Statistic (2)

• The probability of embedding calculated for
  different areas of an image.

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Defending against Statistical Steganalysis

• Pseudo-Random Number Generator
• keyed PRNG to select the redundant data
• selection of Redundant data
• Error Correcting Codes
• use the unmarked Redundant data bits
• embed error correcting codes

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Project Goals

• Implement simple steganographic tools
• Implement steganalysis tool using statistical
  analysis and evaluate the detection rate of this
  tool
• Implement extended steganographic tool that can
  evade statistic analysis and test the stego
  images on the steganalysis tool
• Pseudo-Random Number Generator
• Error Correcting Codes
• Evaluate the detection rate of extended
  steganographic tools with the steganalysis tool

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Tentative Schedule

• April 05 12 Background Research
• April 13 20 Implementation
• April 21 29 Implementation
• April 30 Revision Formal Report

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References

• Niels Provos and Peter Honeyman. "Hide and Seek
  An introduction to Steganography."
  http//niels.xtdnet.nl/papers/practical.pdf
  (MAY/JUNE 2003).
• Neil F. Johnson and Sushil Jajodia. "Steganalysis
  of Images Created Using Current Steganography
  Software." http//www.jjtc.com/ihws98/jjgmu.html
  (1995-2003).
• Ross J. Anderson, Fabien A.P. Petitcolas. "On The
  Limits of Steganography." http//www.petitcolas.ne
  t/fabien/publications/jsac98-limsteg.pdf (May
  1998).
• Hany Farid. "Detecting Steganographic Messages in
  Digital Images." http//www.cs.dartmouth.edu/fari
  d/publications/tr01.pdf
• Saraju P. Mohanty. "Digital Watermarking A
  Tutorial Review." http//www.cs.unt.edu/smohanty/
  research/Reports/MohantyWatermarkingSurvey1999.pdf
  (1999)