From: Andrew.Spring@ping.be (Andrew Spring)
Date: Sat, 15 Jul 95 07:18:36 PDT
To: cypherpunks@toad.com
Subject: Re: def'n of "computer network"
Message-ID: <v01510103ac2ca05c8eb2@[193.74.217.19]>
MIME-Version: 1.0
Content-Type: text/plain


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>rick hoselton writes:
>> Perry, I don't understand.  If the least significant bits in my gif file
>> follow all the "known statistical distributions", how can anyone know
>> whether they are "just noise" or are an encrypted message,

If your attacker has a more sophisticated statistical model of noise
distributions than you do, then he can deduce the existence of message.

>
>Indeed -- how could the recipient even know to look, unless these
>things arrived regularly and with a fully standardized form of
>stegonography, in which case why bother, all you've done is come up
>with a very odd form of transfer encoding.
>
>If the recipient does know to look, that implies either that there is
>a hint, in which case the stegonography is useless, or it implies that
>you have prearrangement, in which case my comments on prearrangement
>hold.

Well, there's things like the subliminal channel in DSS (discussed in Applied
Cryptography) whereby a DSS chip could leak bits of a user's private key.  In
the channel discussed, even if the user suspected the existence of the
channel, there's no way he can prove it.  Now, that's steganography!

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--
Thank you VERY much!  You'll be getting a Handsome Simulfax Copy of your
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<Andrew.Spring@ping.be> PGP Print: 0529 C9AF 613E 9E49  378E 54CD E232 DF96
   Thank you for question, exit left to Funway.