Re: [steghide-devel] Sorry! Ignore the previous e-mail
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From: Stefan H. <sh...@ch...> - 2003-04-27 08:35:46
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=2D----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Sunday 27 April 2003 06:05, Adam Brickman wrote: > I found your suggested tip to copy the module files to the steghide > directory after I sent the e-mail asking for help. Sorry about that. > Do you have any documentation on how your particular algorithm works, in > more detail? I understand that it modifies the LSB's of the cover file. > In my report, I would like to briefly explain how your algorithms works, > including how it choose s which LSB's to modify, what it does with the > other LSB's, its proposed strengths/weaknesses...anything you might have > would help. To understand how it chooses which LSBs to modify you should take a look at= =20 the "distribution method" as described in the man page (the usage.txt file = on=20 Windows) and implemented in the dmtd_* functions in stegano.cc. The other=20 LSBs are not modified. A strength is that the default distribution method=20 automatically chooses the maximum possible interval length (also see man=20 page) thus resulting in an equal distribution of the embedded bits in the=20 cover-file. A weakness is - as with every LSB-based technique - that it is= =20 relativly easy detectable with first-order statistical tests if you embed=20 large amounts of data (see for example: Andreas Westfeld, Andreas Pfitzmann= :=20 Attacks on Steganographic Systems. Information Hiding, 3rd International=20 Workshop, Proceedings, Dresden September/October 1999, LNCS 1768, Springer= =20 Verlag, Berlin 2000, 61--76). The upcoming 0.5.1 version will use an=20 algorithm that is not detectable by first-order statistical tests. Greetings, Stefan Hetzl =2D----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.1 (GNU/Linux) iD8DBQE+q5VFKN/5Ocgn19gRAjNsAJ9k6e92wzyAGpESxOML/Kh+/YBc8wCfWaWm pjwaN+LG8xEAu5M+w/HBAe0=3D =3D/KbF =2D----END PGP SIGNATURE----- |