wok-6.x view outguess/description.txt @ rev 25558
Up libqcow (20221124)
| author | Pascal Bellard <pascal.bellard@slitaz.org> |
|---|---|
| date | Mon Apr 24 09:03:56 2023 +0000 (18 months ago) |
| parents | |
| children |
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1 Outguess is a universal steganographic tool that allows
2 the insertion of hidden information into the redundant
3 bits of data sources.
4 The nature of the data source is irrelevant to the core
5 of outguess. The program relies on data specific handlers
6 that will extract redundant bits and write them back
7 after modification.
8 Currently only the PPM (Portable Pixel Map), PNM
9 (Portable Any Map), and JPEG image formats are supported,
10 although outguess could use any kind of data, as long as
11 a handler were provided.
13 Steganography is the art and science of hiding that
14 communication is happening.
15 Classical steganography systems depend on keeping the
16 encoding system secret, but modern steganography are
17 detectable only if secret information is known, e.g. a
18 secret key.
19 Because of their invasive nature steganography systems
20 leave detectable traces within a medium's characteristics.
21 This allows an eavesdropper to detect media that has been
22 modified, revealing that secret communication is taking
23 place. Although the secrecy of the information is not
24 degraded, its hidden nature is revealed, defeating the
25 main purpose of Steganography.
27 For JPEG images, OutGuess preserves statistics based on
28 frequency counts.
29 As a result, no known statistical test is able to detect
30 the presence of steganographic content.
31 Before embedding data into an image, the OutGuess system
32 can determine the maximum message size that can be hidden
33 while still being able to maintain statistics based on
34 frequency counts.
36 OutGuess uses a generic iterator object to select which
37 bits in the data should be modified.
38 A seed can be used to modify the behavior of the iterator.
39 It is embedded in the data along with the rest of the
40 message. By altering the seed, OutGuess tries to find a
41 sequence of bits that minimizes the number of changes in
42 the data that have to be made.