STEGDETECT(1) BSD General Commands Manual STEGDETECT(1)NAMEstegdetect — finds image files with steganographic content
SYNOPSISstegdetect [-qhnV] [-s float] [-C num,tfname] [-c file ... name]
[-D file] [-d num] [-t tests] [file ...]
DESCRIPTION
The stegdetect utility analyses image files for steganographic content.
It runs statistical tests to determine if steganographic content is
present, and also tries to find the system that has been used to embed
the hidden information.
The options are as follows:
-q Only reports images that are likely to have steganographic con‐
tent.
-h Only calculates the DCT histogram. Use the -d option to dis‐
play the values.
-n Enables checking of JPEG header information to surpress false
positives. If enabled, all JPEG images that contain comment
fields will be treated as negatives. OutGuess checking will be
disabled if the JFIF marker does not match version 1.1.
-V Displays the version number of the software.
-s float Changes the sensitivity of the detection algorithms. Their
results are multiplied by the specified number. The higher the
number the more sensitive the test will become. The default is
1.
-C num,tfname
Feature vectors are being extraced from the images. The argu‐
ment num can either be zero or one. A zero indicates that the
provided images do not contain steganographic content, a one
indicates that they do. The argument tfname is the name of
transform used for feature extraction. The features vectores
are printed to stdout.
-c file Reads the data created by the -C options and computes the nec‐
essary values to detect steganographic content in yet unknown
images. The option can be used multiple times. It expects
that the name of the scheme provided as additional argument.
The result is a decision object that can be used with the -D
option. The decision object contains a the parameters for a
linear discriminant function based on the Neyman-Pearson theo‐
rem.
-D file Reads a decision object that contains detection information
about a new steganographic scheme.
-d num Prints debug information.
-t tests Sets the tests that are being run on the image. The following
characters are understood:
j Tests if information has been embedded with jsteg.
o Tests if information has been embedded with outguess.
p Tests if information has been embedded with jphide.
i Tests if information has been hidden with invisible
secrets.
f Tests if information has been hidden with F5.
F Tests if information has been hidden with F5 using a
more sophisticated but fairly slow detection algorithm.
a Tests if information has been added at the end of file,
for example by camouflage or appendX.
The default value is jopifa.
The stegdetect utility indicates the accuracy of the detection with a
number of stars behind the detected system. If no filenames have been
specified, stegdetect will read the filenames from stdin.
EXAMPLESstegdetect-t p auto.jpg
Tries to detect the presence of jphide embedded information in auto.jpg.
ERRORSstegdetect works only for JPEG images.
Currently, there is no support for parameter training. The only exported
knob is the sensitivity level. Future versions will export all detection
parameters via a configuration file.
SEE ALSOstegbreak(1)ACKNOWLEDGEMENTS
This product includes software developed by Ian F. Darwin and others.
The stegdetect utility uses Darwin's file magic to identify data appended
at the end of an image.
AUTHORS
The stegdetect utility has been developed by Niels Provos.
BSD April 01, 2001 BSD
