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The following archive was created by hippie-mail 7.98617-22 on Sat Apr 10 1999 - 01:11:02
Russell Nelson (nelson@crynwr.com)
31 Aug 1998 02:31:23 -0000
Anonymous writes:
> One method of steganography is to hide the embedded message by means of
> changing random elements of the cover message. For example, the cover
> message may have various words where synonyms can be substituted.
> Everywhere the word "couch" appears it could be substituted with
> "sofa" and vice versa.
I must respectfully disagree. The problem of stego is not hiding
messages. There's plenty of extant noisy bits to hide messages in
(e.g. treat the lengths of the lines of this message as the width of
pulses, and use some pulse width modulation to get your bits out).
The problem is one of detecting the presence of a message. If the
output of the stego algorithm has a signature, then an attacker can
detect the presence of the message, which means that the stego
algorithm has failed.
If the output of the stego algorithm is completely random bits, then
how do you know that there's a message? Answer is, "you decode it."
But do you go around decoding every random sequence of bits that
happens into your life? No, you have a standard place to look for
messages. Well, if it's standard, then the attacker knows where to
look as well. But if the attacker knows where to look, then your
stego algorithm had better have perfectly random output.
Using a shared secret list of synonyms is nice, but it suffers from
all the usual problems of key distribution.
-- -russ nelson <rn-sig@crynwr.com> http://crynwr.com/~nelson Crynwr supports Open Source(tm) Software| PGPok | Freedom is the primary 521 Pleasant Valley Rd. | +1 315 268 1925 voice | cause of Peace, Love, Potsdam, NY 13676-3213 | +1 315 268 9201 FAX | Truth and Justice.
The following archive was created by hippie-mail 7.98617-22 on Sat Apr 10 1999 - 01:11:02