Steganography%20with%20Digital%20Images - PowerPoint PPT Presentation

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Steganography%20with%20Digital%20Images

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Steganography with Digital Images. By. Karl Schramm. Generic Stegosystem. Embedding Algorithm ... The message must be contained in the cover data. Use error ... – PowerPoint PPT presentation

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Title: Steganography%20with%20Digital%20Images


1
Steganography with Digital Images
  • By
  • Karl Schramm

2
Generic Stegosystem
3
Embedding Guidelines
  • Alteration must be invisible
  • Dont alter the header
  • The message must be contained in the cover data
  • Use error-correcting code if possible
  • Dont reuse the cover data

4
LSB Modification
  • Hide data by altering the LSB of a pixel
  • Choose pixels pseudo-randomly
  • Works with both true color and color index modes

5
JPEG Algorithms
  • Modify discrete cosine transform (DCT)
    coefficients
  • Choose either larger coefficient values or
    coefficients in a particular range

6
Patchwork
  • Choose random pixel pairs
  • Let d p1 p2
  • Encode information with values
  • d lt 0 0
  • d gt 0 1
  • Swap the pixels if necessary
  • If d 0, choose a new pair

7
Steganalysis
  • Traffic analysis
  • Detection
  • Brute force
  • Manipulation
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