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Re: Subliminal Channels
wonderer wrote:
>Is there any published work on hiding subliminal messages
>in pictures? It seems like that would be really easy.
Someone did write a program which embeds information in a JPEG, but I
don't have any other info (like where to get it, who wrote it, etc.
:-)
Actually though, embedding a message in a picture leans toward
steganography.
Subliminal channels, covert channels, and steganography are related to
one another, and seem to overlap. I don't have precise definitions
(does anybody else?). From reading, here is what I think these three
methods are:
Covert channel: you and I agree that if I mail you a letter with the
stamp affixed sideways, that messageA is communicated. Or, we agree
that a post sent to alt.test with the subject "el mariachi" conveys
messageA. Or that my running a process and killing before 9:30 p.m.
conveys messageA.
Subliminal channel: you and I share a secret and convey our message in
the digital signature of innocent message we pass to one another.
Steganography: I write an innocent message, and I change the spacing
between words, to convey messageA. Or, I embed the message in the low
order bits of a picture or a sound file.
So, it looks like that in subliminal channels and steganography, the
actual message is passed, while covert channels don't (it's like
winking at a friend - no message but lots of information).
Also, it seems that steganography alters the innocent message itself,
while a subliminal channel doesn't.
Obviously, there is great room for hair-splitting. These are the
differences as I understand them! Any other input?
--
Karl L. Barrus: [email protected]
keyID: 5AD633 hash: D1 59 9D 48 72 E9 19 D5 3D F3 93 7E 81 B5 CC 32
"One man's mnemonic is another man's cryptography"
- my compilers prof discussing file naming in public directories