1994-02-28 - Re: standard for stegonography?

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From: tcmay@netcom.com (Timothy C. May)
To: cypherpunks@toad.com
Message Hash: 8d7f28d2bc077731b710ed4a950466a3ce591fba48dc250cf910c41638fa1860
Message ID: <199402280201.SAA29516@netcom9.netcom.com>
Reply To: <199402280131.RAA26338@netcom9.netcom.com>
UTC Datetime: 1994-02-28 02:00:33 UTC
Raw Date: Sun, 27 Feb 94 18:00:33 PST

Raw message

From: tcmay@netcom.com (Timothy C. May)
Date: Sun, 27 Feb 94 18:00:33 PST
To: cypherpunks@toad.com
Subject: Re: standard for stegonography?
In-Reply-To: <199402280131.RAA26338@netcom9.netcom.com>
Message-ID: <199402280201.SAA29516@netcom9.netcom.com>
MIME-Version: 1.0
Content-Type: text/plain

Jeff Poskanzer caught the typo in my post:

> I'm sure this is the "standard" being talked about. (BTW, I agree that
> including trivially-readable messages like "***Begin Stego Block
> Now*** is a dumb idea....with reasonable standards for block size,
> e.g., the signal bits are the LSBs of the largest sub-block that's an
> even power of 1, no such headers are needed.)

Obviously I meant even power of 2. 

While I'm at it, I'll elaborate for a bit.

If an image file or audio sample file of, say, 12319 bytes is
received, one might "standardize" (voluntarily, of course) on the
first 8192 bytes as representing the place to look for the LSB

Alternatively, *all* of the LSB bits could be looked at, with messages
just padded-out with random bits to fill out the full amount. 

Lots of options for standards. As others have noted, you just don't
want to have to flag what standard you're using in the message itself
(in plaintext, else why bother?) as that means the stego use is not
longer plausibly deniable.

--Tim May

Timothy C. May         | Crypto Anarchy: encryption, digital money,  
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