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Tue Nov 4 11:50:11 PST 2008

[1]the physics arXiv blog

   [2]Breakthrough calculations on the capacity of a steganographic

   Posted: 03 Nov 2008 11:49 PM CST


   Steganography is the art of hiding a message in such a way that only
   the sender and receiver realise it is there. (By contrast,
   cryptography disguises the content of a message but makes no attempt
   to hide it.)

   The central problem for steganographers is how much data can be hidden
   without being detected. But the complexity of the problem means it has
   been largely ignored in favor of more easily solved conundrums.

   Jeremiah Harmsen from Google Inc in Mountain View and William Pearlman
   at Rensselaer Polytechnic Institute in Troy NY, say: "while false
   alarms and missed signals have rightfully dominated the steganalysis
   literature, very little is known about the amount of information that
   can be sent past these algorithms."

   So the pair have taken an important step to change that. Their
   approach is to think along the same lines as Claude Shannon in his
   famous determination of the capacity of a noisy channel. In Shannon's
   theory, a transmission is considered successful if the decoder
   properly determines which message the encoder has sent. In the
   stego-channel, a transmission is successful if the decoder properly
   determines the sent message without anybody else detecting its

   Previous attempts have all placed limits on the steganographers
   channel for example, by stipulating that the hidden data, or
   stego-channel, has the same distribution as the cover channel. But
   Harmsen and Pearlman have take a more general approach which takes
   some important steps towards working out the channel capacity over a
   much wider range of conditions.

   The results are interesting and in some cases counter-intuitive (for
   example, adding noise to channel can increase its steganographic
   capacity and in some cases, mounting two attacks on a channel instead
   of one can do the same).

   It's fair to say that Harmsen and Pearlman are pioneering of the study
   of steganographic capacity and that with this breakthrough, the field
   looks rich with low hanging fruit. Expect more!

   Ref: [4] Capacity of Steganographic Channels

   [6][arXivblog?i=KtAON] [7][arXivblog?i=4bYNN] [8][arXivblog?i=vTEyn]
   [9][arXivblog?i=dwzIN] [10][arXivblog?i=ty7nn] [11][arXivblog?i=FpGdN]
   [12][arXivblog?i=oaKyn] [13][arXivblog?i=Ao24N] 
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