Re: Simple inner transposition steganography

[edo]

Come on, this is a terrible idea for steganography.  Unless this catches
on as some sort of fad, which (a) it won't and (b) even if it did it
would be short-lived, then sending a message with its letters scrambled
in this way would be the last thing you'd want to do for steganography.

The whole point of steganography is to make the cover message look normal.
Nothing would make your message more conspicuous than being filled with
random letter rearrangements.  In fact, this is such an obvious and
forced alteration that it hardly counts as steganography at all.

Maybe it works as a very, very weak form of encryption, one which can
be decrypted at a glance by humans but would evade the most simplistic
computer recognition systems.  But stego it ain't.

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Re: Simple inner transposition steganography

[Peter Wayner]

At 4:01 PM -0400 9/18/03, [EMAIL PROTECTED] wrote:
On Thu, 18 Sep 2003, edo wrote:

 Maybe it works as a very, very weak form of encryption, one which can
 be decrypted at a glance by humans but would evade the most simplistic
 computer recognition systems.  But stego it ain't.
Steganography is in the eye of the beholder.
Very nice line.

I have to agree. There are always two channels in steganography and 
its cousin watermarking. You want to make changes in one channel so 
the other channel isn't affected. In this case, a munged word doesn't 
affect the human reader but it can carry log_2(n!) bits where n=count 
of non-duplicate letters - 2. So we have two channels.

Now, I will admit that a large number of munged words will trigger 
something in the human, but it's entirely possible that three or four 
munged words on a page WON'T EVEN BE NOTICED. Believe me. I've proof 
read books a number of times and it's surprising how much gets 
through even the best copy editors.

Three or four words per page is also enough to insert more than a few 
bits of watermarking. A seven letter word can carry almost seven 
bits. So let's call it 6 bits. If you change four seven letter words 
on a page, you've 24 bits. Not bad.



-Peter

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