[MacPorts] #31723: add Gifshuffle
MacPorts
noreply at macports.org
Sat Oct 22 11:12:40 PDT 2011
#31723: add Gifshuffle
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Reporter: fyodor.vassiley@… | Owner: macports-tickets@…
Type: request | Status: new
Priority: Low | Milestone:
Component: ports | Version: 2.0.3
Keywords: Gifshuffle steganography ceh | Port:
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GIF colourmap steganography
The program gifshuffle is used to conceal messages in GIF images by
shuffling the colourmap, which leaves the image visibly unchanged.
gifshuffle works with all GIF images, including those with transparency
and animation, and in addition provides compression and encryption of the
concealed message.
As of 21 January 2003, this site contains gifshuffle 2.0. This is the
first update in nearly five years! Changes involve tweaks to a few GIF
encoding characteristics, plus an improvement to the way encrypted
messages are encoded. These should further reduce the chances of concealed
messages being detected.
How does it work?
Any list of n items can be sorted n! ways, meaning that any particular
ordering can represent a number in the range [0, n!-1]. This number can in
turn store approximately log2(n!) bits of information. Thus, a GIF image
with 256 colours can store up to 1683 bits (210 bytes) of information by
shuffling the colours in its colourmap.
It's free!
The gifshuffle program is public domain, and source code can be downloaded
from this page. There are no patents or copyrights, so its use is
unrestricted. Naturally, if you do decide to use it, the author would love
to hear about it.
http://www.darkside.com.au/gifshuffle/
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Ticket URL: <https://trac.macports.org/ticket/31723>
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