Cryptography Reference
In-Depth Information
How to Use It
The best steganalysis is aimed at individual algorithms
and the particular statistical anomalies they leave behind. The
best solution is to learn which software is being used and ana-
lyze it for characteristic marks. More general solutions are usu-
ally far from accurate. The best general solution is to check the
randomness of the least significant bits. Toomuch randomness
may be a sign of steganography— or a sign of a very good cam-
era.
Further Reading
•
The
Investigator's Guide to Steganography
by Gregory Kip-
per describesmany of themajor programs floating around
the Internet and explains some techniques for detecting
when they've been used. [Kip03]
•
Nicholas Zhong-Yang Ho and Ee-Chien Chang show how
it is possible to identify the information in redacted docu-
ments by looking at the edge effects like the ones in Figure
17.3. If the redaction does not black out the entire
8
8
block, some residual effects from JPG compression will be
left behind. This may be enough to recover the informa-
tion removed during redaction. [HC08]
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