1. Steganography with Digital ImagesBy
Karl Schramm

2. Generic Stegosystem Cover Data Key Stego Data Embedding Algorithm
Secret Message

3. Embedding Guidelines Alteration must be invisible
Don’t alter the header
The message must be contained in the cover data
Use error-correcting code if possible
Don’t 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
Blue 220
Blue 221

5. JPEG Algorithms Modify discrete cosine transform (DCT) coefficients
Choose either larger coefficient values or coefficients in a particular range
Attack at dawn!

6. Patchwork Choose random pixel pairs Let d = p1 – p2
Encode information with values:
d < 0 == 0
d > 0 == 1
Swap the pixels if necessary
If d == 0, choose a new pair

7. Steganalysis
Traffic analysis
Detection
Brute force
Manipulation